Sasha reported:
[ 3494.030114] UBSAN: Undefined behaviour in kernel/events/ring_buffer.c:685:22
[ 3494.030647] shift exponent -1 is negative
Andrey spotted that this is because:
It happens if nr_pages = 0:
rb->page_order = ilog2(nr_pages);
Fix it by making both assignments conditional on nr_pages; since
otherwise they should both be 0 anyway, and will be because of the
kzalloc() used to allocate the structure.
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Reported-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20160129141751.GA407@worktop
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There were two problems with the dynamic interrupt throttle mechanism,
both triggered by the same action.
When you (or perf_fuzzer) write a huge value into
/proc/sys/kernel/perf_event_max_sample_rate the computed
perf_sample_allowed_ns becomes 0. This effectively disables the whole
dynamic throttle.
This is fixed by ensuring update_perf_cpu_limits() never sets the
value to 0. However, we allow disabling of the dynamic throttle by
writing 100 to /proc/sys/kernel/perf_cpu_time_max_percent. This will
generate a warning in dmesg.
The second problem is that by setting the max_sample_rate to a huge
number, the adaptive process can take a few tries, since it halfs the
limit each time. Change that to directly compute a new value based on
the observed duration.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Its possible to IOC_PERIOD while the event is throttled, this would
re-start the event and the next tick would then try to unthrottle it,
and find the event wasn't actually stopped anymore.
This would tickle a WARN in the x86-pmu code which isn't expecting to
start a !stopped event.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: dvyukov@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160310143924.GR6356@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86 protection key support from Ingo Molnar:
"This tree adds support for a new memory protection hardware feature
that is available in upcoming Intel CPUs: 'protection keys' (pkeys).
There's a background article at LWN.net:
https://lwn.net/Articles/643797/
The gist is that protection keys allow the encoding of
user-controllable permission masks in the pte. So instead of having a
fixed protection mask in the pte (which needs a system call to change
and works on a per page basis), the user can map a (handful of)
protection mask variants and can change the masks runtime relatively
cheaply, without having to change every single page in the affected
virtual memory range.
This allows the dynamic switching of the protection bits of large
amounts of virtual memory, via user-space instructions. It also
allows more precise control of MMU permission bits: for example the
executable bit is separate from the read bit (see more about that
below).
This tree adds the MM infrastructure and low level x86 glue needed for
that, plus it adds a high level API to make use of protection keys -
if a user-space application calls:
mmap(..., PROT_EXEC);
or
mprotect(ptr, sz, PROT_EXEC);
(note PROT_EXEC-only, without PROT_READ/WRITE), the kernel will notice
this special case, and will set a special protection key on this
memory range. It also sets the appropriate bits in the Protection
Keys User Rights (PKRU) register so that the memory becomes unreadable
and unwritable.
So using protection keys the kernel is able to implement 'true'
PROT_EXEC on x86 CPUs: without protection keys PROT_EXEC implies
PROT_READ as well. Unreadable executable mappings have security
advantages: they cannot be read via information leaks to figure out
ASLR details, nor can they be scanned for ROP gadgets - and they
cannot be used by exploits for data purposes either.
We know about no user-space code that relies on pure PROT_EXEC
mappings today, but binary loaders could start making use of this new
feature to map binaries and libraries in a more secure fashion.
There is other pending pkeys work that offers more high level system
call APIs to manage protection keys - but those are not part of this
pull request.
Right now there's a Kconfig that controls this feature
(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) that is default enabled
(like most x86 CPU feature enablement code that has no runtime
overhead), but it's not user-configurable at the moment. If there's
any serious problem with this then we can make it configurable and/or
flip the default"
* 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (38 commits)
x86/mm/pkeys: Fix mismerge of protection keys CPUID bits
mm/pkeys: Fix siginfo ABI breakage caused by new u64 field
x86/mm/pkeys: Fix access_error() denial of writes to write-only VMA
mm/core, x86/mm/pkeys: Add execute-only protection keys support
x86/mm/pkeys: Create an x86 arch_calc_vm_prot_bits() for VMA flags
x86/mm/pkeys: Allow kernel to modify user pkey rights register
x86/fpu: Allow setting of XSAVE state
x86/mm: Factor out LDT init from context init
mm/core, x86/mm/pkeys: Add arch_validate_pkey()
mm/core, arch, powerpc: Pass a protection key in to calc_vm_flag_bits()
x86/mm/pkeys: Actually enable Memory Protection Keys in the CPU
x86/mm/pkeys: Add Kconfig prompt to existing config option
x86/mm/pkeys: Dump pkey from VMA in /proc/pid/smaps
x86/mm/pkeys: Dump PKRU with other kernel registers
mm/core, x86/mm/pkeys: Differentiate instruction fetches
x86/mm/pkeys: Optimize fault handling in access_error()
mm/core: Do not enforce PKEY permissions on remote mm access
um, pkeys: Add UML arch_*_access_permitted() methods
mm/gup, x86/mm/pkeys: Check VMAs and PTEs for protection keys
x86/mm/gup: Simplify get_user_pages() PTE bit handling
...
Pull networking updates from David Miller:
"Highlights:
1) Support more Realtek wireless chips, from Jes Sorenson.
2) New BPF types for per-cpu hash and arrap maps, from Alexei
Starovoitov.
3) Make several TCP sysctls per-namespace, from Nikolay Borisov.
4) Allow the use of SO_REUSEPORT in order to do per-thread processing
of incoming TCP/UDP connections. The muxing can be done using a
BPF program which hashes the incoming packet. From Craig Gallek.
5) Add a multiplexer for TCP streams, to provide a messaged based
interface. BPF programs can be used to determine the message
boundaries. From Tom Herbert.
6) Add 802.1AE MACSEC support, from Sabrina Dubroca.
7) Avoid factorial complexity when taking down an inetdev interface
with lots of configured addresses. We were doing things like
traversing the entire address less for each address removed, and
flushing the entire netfilter conntrack table for every address as
well.
8) Add and use SKB bulk free infrastructure, from Jesper Brouer.
9) Allow offloading u32 classifiers to hardware, and implement for
ixgbe, from John Fastabend.
10) Allow configuring IRQ coalescing parameters on a per-queue basis,
from Kan Liang.
11) Extend ethtool so that larger link mode masks can be supported.
From David Decotigny.
12) Introduce devlink, which can be used to configure port link types
(ethernet vs Infiniband, etc.), port splitting, and switch device
level attributes as a whole. From Jiri Pirko.
13) Hardware offload support for flower classifiers, from Amir Vadai.
14) Add "Local Checksum Offload". Basically, for a tunneled packet
the checksum of the outer header is 'constant' (because with the
checksum field filled into the inner protocol header, the payload
of the outer frame checksums to 'zero'), and we can take advantage
of that in various ways. From Edward Cree"
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1548 commits)
bonding: fix bond_get_stats()
net: bcmgenet: fix dma api length mismatch
net/mlx4_core: Fix backward compatibility on VFs
phy: mdio-thunder: Fix some Kconfig typos
lan78xx: add ndo_get_stats64
lan78xx: handle statistics counter rollover
RDS: TCP: Remove unused constant
RDS: TCP: Add sysctl tunables for sndbuf/rcvbuf on rds-tcp socket
net: smc911x: convert pxa dma to dmaengine
team: remove duplicate set of flag IFF_MULTICAST
bonding: remove duplicate set of flag IFF_MULTICAST
net: fix a comment typo
ethernet: micrel: fix some error codes
ip_tunnels, bpf: define IP_TUNNEL_OPTS_MAX and use it
bpf, dst: add and use dst_tclassid helper
bpf: make skb->tc_classid also readable
net: mvneta: bm: clarify dependencies
cls_bpf: reset class and reuse major in da
ldmvsw: Checkpatch sunvnet.c and sunvnet_common.c
ldmvsw: Add ldmvsw.c driver code
...
Pull x86 asm updates from Ingo Molnar:
"This is another big update. Main changes are:
- lots of x86 system call (and other traps/exceptions) entry code
enhancements. In particular the complex parts of the 64-bit entry
code have been migrated to C code as well, and a number of dusty
corners have been refreshed. (Andy Lutomirski)
- vDSO special mapping robustification and general cleanups (Andy
Lutomirski)
- cpufeature refactoring, cleanups and speedups (Borislav Petkov)
- lots of other changes ..."
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits)
x86/cpufeature: Enable new AVX-512 features
x86/entry/traps: Show unhandled signal for i386 in do_trap()
x86/entry: Call enter_from_user_mode() with IRQs off
x86/entry/32: Change INT80 to be an interrupt gate
x86/entry: Improve system call entry comments
x86/entry: Remove TIF_SINGLESTEP entry work
x86/entry/32: Add and check a stack canary for the SYSENTER stack
x86/entry/32: Simplify and fix up the SYSENTER stack #DB/NMI fixup
x86/entry: Only allocate space for tss_struct::SYSENTER_stack if needed
x86/entry: Vastly simplify SYSENTER TF (single-step) handling
x86/entry/traps: Clear DR6 early in do_debug() and improve the comment
x86/entry/traps: Clear TIF_BLOCKSTEP on all debug exceptions
x86/entry/32: Restore FLAGS on SYSEXIT
x86/entry/32: Filter NT and speed up AC filtering in SYSENTER
x86/entry/compat: In SYSENTER, sink AC clearing below the existing FLAGS test
selftests/x86: In syscall_nt, test NT|TF as well
x86/asm-offsets: Remove PARAVIRT_enabled
x86/entry/32: Introduce and use X86_BUG_ESPFIX instead of paravirt_enabled
uprobes: __create_xol_area() must nullify xol_mapping.fault
x86/cpufeature: Create a new synthetic cpu capability for machine check recovery
...
Pull NOHZ updates from Ingo Molnar:
"NOHZ enhancements, by Frederic Weisbecker, which reorganizes/refactors
the NOHZ 'can the tick be stopped?' infrastructure and related code to
be data driven, and harmonizes the naming and handling of all the
various properties"
[ This makes the ugly "fetch_or()" macro that the scheduler used
internally a new generic helper, and does a bad job at it.
I'm pulling it, but I've asked Ingo and Frederic to get this
fixed up ]
* 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched-clock: Migrate to use new tick dependency mask model
posix-cpu-timers: Migrate to use new tick dependency mask model
sched: Migrate sched to use new tick dependency mask model
sched: Account rr tasks
perf: Migrate perf to use new tick dependency mask model
nohz: Use enum code for tick stop failure tracing message
nohz: New tick dependency mask
nohz: Implement wide kick on top of irq work
atomic: Export fetch_or()
Several cases of overlapping changes, as well as one instance
(vxlan) of a bug fix in 'net' overlapping with code movement
in 'net-next'.
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull nohz enhancements from Frederic Weisbecker:
"Currently in nohz full configs, the tick dependency is checked
asynchronously by nohz code from interrupt and context switch for each
concerned subsystem with a set of function provided by these. Such
functions are made of many conditions and details that can be heavyweight
as they are called on fastpath: sched_can_stop_tick(),
posix_cpu_timer_can_stop_tick(), perf_event_can_stop_tick()...
Thomas suggested a few months ago to make that tick dependency check
synchronous. Instead of checking subsystems details from each interrupt
to guess if the tick can be stopped, every subsystem that may have a tick
dependency should set itself a flag specifying the state of that
dependency. This way we can verify if we can stop the tick with a single
lightweight mask check on fast path.
This conversion from a pull to a push model to implement tick dependency
is the core feature of this patchset that is split into:
* Nohz wide kick simplification
* Improve nohz tracing
* Introduce tick dependency mask
* Migrate scheduler, posix timers, perf events and sched clock tick
dependencies to the tick dependency mask."
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The error path in perf_event_open() is such that asking for a sampling
event on a PMU that doesn't generate interrupts will end up in dropping
the perf_sched_count even though it hasn't been incremented for this
event yet.
Given a sufficient amount of these calls, we'll end up disabling
scheduler's jump label even though we'd still have active events in the
system, thereby facilitating the arrival of the infernal regions upon us.
I'm fixing this by moving account_event() inside perf_event_alloc().
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/1456917854-29427-1-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Instead of providing asynchronous checks for the nohz subsystem to verify
perf event tick dependency, migrate perf to the new mask.
Perf needs the tick for two situations:
1) Freq events. We could set the tick dependency when those are
installed on a CPU context. But setting a global dependency on top of
the global freq events accounting is much easier. If people want that
to be optimized, we can still refine that on the per-CPU tick dependency
level. This patch dooesn't change the current behaviour anyway.
2) Throttled events: this is a per-cpu dependency.
Reviewed-by: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
As Jiri pointed out, this recent commit:
f872f5400c ("mm: Add a vm_special_mapping.fault() method")
breaks uprobes: __create_xol_area() doesn't initialize the new ->fault()
method and this obviously leads to kernel crash when the application
tries to execute the probed insn after bp hit.
We probably want to add uprobes_special_mapping_fault(), this allows to
turn xol_area->xol_mapping into a single instance of vm_special_mapping.
But we need a simple fix, so lets change __create_xol() to nullify the
new member as Jiri suggests.
Suggested-by: Jiri Olsa <jolsa@redhat.com>
Reported-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <tipbot@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Anand <panand@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160227221128.GA29565@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since there is no serialization between task_function_call() doing
task_curr() and the other CPU doing context switches, we could end
up not sending an IPI even if we had to.
And I'm not sure I still buy my own argument we're OK.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174948.340031200@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Completely reworks perf_install_in_context() (again!) in order to
ensure that there will be no ctx time hole between add_event_to_ctx()
and any potential ctx_sched_in().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174948.279399438@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The recent commit 3e349507d1 ("perf: Fix perf_enable_on_exec() event
scheduling") caused this by moving task_ctx_sched_out() from before
__perf_event_mask_enable() to after it.
The overlooked consequence of that change is that task_ctx_sched_out()
would update the ctx time fields, and now __perf_event_mask_enable()
uses stale time.
In order to fix this, explicitly stop our context's time before
enabling the event(s).
Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Fixes: 3e349507d1 ("perf: Fix perf_enable_on_exec() event scheduling")
Link: http://lkml.kernel.org/r/20160224174948.159242158@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently any ctx_sched_in() call will re-start the ctx time tracking,
this means that calls like:
ctx_sched_in(.event_type = EVENT_PINNED);
ctx_sched_in(.event_type = EVENT_FLEXIBLE);
will have a hole in their ctx time tracking. This is likely harmless
but can confuse things a little. By adding EVENT_TIME, we can have the
first ctx_sched_in() (is_active: 0 -> !0) start the time and any
further ctx_sched_in() will leave the timestamps alone.
Secondly, this allows for an early disable like:
ctx_sched_out(.event_type = EVENT_TIME);
which would update the ctx time (if the ctx is active) and any further
calls to ctx_sched_out() would not further modify the ctx time.
For ctx_sched_in() any 0 -> !0 transition will automatically include
EVENT_TIME.
For ctx_sched_out(), any transition that clears EVENT_ALL will
automatically clear EVENT_TIME.
These two rules ensure that under normal circumstances we need not
bother with EVENT_TIME and get natural ctx time behaviour.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174948.100446561@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Because event_sched_out() checks event->pending_disable _before_
actually disabling the event, it can happen that the event fires after
it checks but before it gets disabled.
This would leave event->pending_disable set and the queued irq_work
will try and process it.
However, if the event trigger was during schedule(), the event might
have been de-scheduled by the time the irq_work runs, and
perf_event_disable_local() will fail.
Fix this by checking event->pending_disable _after_ we call
event->pmu->del(). This depends on the latter being a compiler
barrier, such that the compiler does not lift the load and re-creates
the problem.
Tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174948.040469884@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
perf_install_in_context() relies upon the context switch hooks to have
scheduled in events when the IPI misses its target -- after all, if
the task has moved from the CPU (or wasn't running at all), it will
have to context switch to run elsewhere.
This however doesn't appear to be happening.
It is possible for the IPI to not happen (task wasn't running) only to
later observe the task running with an inactive context.
The only possible explanation is that the context switch hooks are not
called. Therefore put in a sync_sched() after toggling the jump_label
to guarantee all CPUs will have them enabled before we install an
event.
A simple if (0->1) sync_sched() will not in fact work, because any
further increment can race and complete before the sync_sched().
Therefore we must jump through some hoops.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174947.980211985@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Alexander reported that when the 'original' context gets destroyed, no
new clones happen.
This can happen irrespective of the ctx switch optimization, any task
can die, even the parent, and we want to continue monitoring the task
hierarchy until we either close the event or no tasks are left in the
hierarchy.
perf_event_init_context() will attempt to pin the 'parent' context
during clone(). At that point current is the parent, and since current
cannot have exited while executing clone(), its context cannot have
passed through perf_event_exit_task_context(). Therefore
perf_pin_task_context() cannot observe ctx->task == TASK_TOMBSTONE.
However, since inherit_event() does:
if (parent_event->parent)
parent_event = parent_event->parent;
it looks at the 'original' event when it does: is_orphaned_event().
This can return true if the context that contains the this event has
passed through perf_event_exit_task_context(). And thus we'll fail to
clone the perf context.
Fix this by adding a new state: STATE_DEAD, which is set by
perf_release() to indicate that the filedesc (or kernel reference) is
dead and there are no observers for our data left.
Only for STATE_DEAD will is_orphaned_event() be true and inhibit
cloning.
STATE_EXIT is otherwise preserved such that is_event_hup() remains
functional and will report when the observed task hierarchy becomes
empty.
Reported-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Fixes: c6e5b73242 ("perf: Synchronously clean up child events")
Link: http://lkml.kernel.org/r/20160224174947.919845295@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In the err_file: fput(event_file) case, the event will not yet have
been attached to a context. However perf_release() does assume it has
been. Cure this.
Tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174947.793996260@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In case of: err_file: fput(event_file), we'll end up calling
perf_release() which in turn will free the event.
Do not then free the event _again_.
Tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174947.697350349@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Consider the following scenario:
CPU0 CPU1
ctx = find_get_ctx();
perf_event_exit_task_context()
mutex_lock(&ctx->mutex);
perf_install_in_context(ctx, ...);
/* NO-OP */
mutex_unlock(&ctx->mutex);
...
perf_release()
WARN_ON_ONCE(event->state != STATE_EXIT);
Since the event doesn't pass through perf_remove_from_context()
because perf_install_in_context() NO-OPs because the ctx is dead, and
perf_event_exit_task_context() will not observe the event because its
not attached yet, the event->state will not be set.
Solve this by revalidating ctx->task after we acquire ctx->mutex and
failing the event creation as a whole.
Tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174947.626853419@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Conflicts:
drivers/net/phy/bcm7xxx.c
drivers/net/phy/marvell.c
drivers/net/vxlan.c
All three conflicts were cases of simple overlapping changes.
Signed-off-by: David S. Miller <davem@davemloft.net>
. avoid walking the stack when there is no room left in the buffer
. generalize get_perf_callchain() to be called from bpf helper
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
If CPU_UP_PREPARE is called it is not guaranteed, that a previously allocated
and assigned hash has been freed already, but perf_event_init_cpu()
unconditionally allocates and assignes a new hash if the swhash is referenced.
By overwriting the pointer the existing hash is not longer accessible.
Verify that there is no hash assigned on this cpu before allocating and
assigning a new one.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20160209201007.843269966@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If CPU_DOWN_PREPARE fails the perf hotplug notifier is called for
CPU_DOWN_FAILED and calls perf_event_init_cpu(), which checks whether the
swhash is referenced. If yes it allocates a new hash and stores the pointer in
the per cpu data structure.
But at this point the cpu is still online, so there must be a valid hash
already. By overwriting the pointer the existing hash is not longer
accessible.
Remove the CPU_DOWN_FAILED state, as there is nothing to (re)allocate.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20160209201007.763417379@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If CPU_UP_PREPARE fails the perf hotplug code calls perf_event_exit_cpu(),
which is a pointless exercise. The cpu is not online, so the smp function
calls return -ENXIO. So the result is a list walk to call noops.
Remove it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20160209201007.682184765@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
For protection keys, we need to understand whether protections
should be enforced in software or not. In general, we enforce
protections when working on our own task, but not when on others.
We call these "current" and "remote" operations.
This patch introduces a new get_user_pages() variant:
get_user_pages_remote()
Which is a replacement for when get_user_pages() is called on
non-current tsk/mm.
We also introduce a new gup flag: FOLL_REMOTE which can be used
for the "__" gup variants to get this new behavior.
The uprobes is_trap_at_addr() location holds mmap_sem and
calls get_user_pages(current->mm) on an instruction address. This
makes it a pretty unique gup caller. Being an instruction access
and also really originating from the kernel (vs. the app), I opted
to consider this a 'remote' access where protection keys will not
be enforced.
Without protection keys, this patch should not change any behavior.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: jack@suse.cz
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20160212210154.3F0E51EA@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull perf fixes from Thomas Gleixner:
"This is much bigger than typical fixes, but Peter found a category of
races that spurred more fixes and more debugging enhancements. Work
started before the merge window, but got finished only now.
Aside of that this contains the usual small fixes to perf and tools.
Nothing particular exciting"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (43 commits)
perf: Remove/simplify lockdep annotation
perf: Synchronously clean up child events
perf: Untangle 'owner' confusion
perf: Add flags argument to perf_remove_from_context()
perf: Clean up sync_child_event()
perf: Robustify event->owner usage and SMP ordering
perf: Fix STATE_EXIT usage
perf: Update locking order
perf: Remove __free_event()
perf/bpf: Convert perf_event_array to use struct file
perf: Fix NULL deref
perf/x86: De-obfuscate code
perf/x86: Fix uninitialized value usage
perf: Fix race in perf_event_exit_task_context()
perf: Fix orphan hole
perf stat: Do not clean event's private stats
perf hists: Fix HISTC_MEM_DCACHELINE width setting
perf annotate browser: Fix behaviour of Shift-Tab with nothing focussed
perf tests: Remove wrong semicolon in while loop in CQM test
perf: Synchronously free aux pages in case of allocation failure
...
Now that the perf_event_ctx_lock_nested() call has moved from
put_event() into perf_event_release_kernel() the first reason is no
longer valid as that can no longer happen.
The second reason seems to have been invalidated when Al Viro made fput()
unconditionally async in the following commit:
4a9d4b024a ("switch fput to task_work_add")
such that munmap()->fput()->release()->perf_release() would no longer happen.
Therefore, remove the annotation. This should increase the efficiency
of lockdep coverage of perf locking.
Suggested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The orphan cleanup workqueue doesn't always catch orphans, for example,
if they never schedule after they are orphaned. IOW, the event leak is
still very real. It also wouldn't work for kernel counters.
Doing it synchonously is a little hairy due to lock inversion issues,
but is made to work.
Patch based on work by Alexander Shishkin.
Suggested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: vince@deater.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There are two concepts of owner wrt an event and they are conflated:
- event::owner / event::owner_list,
used by prctl(.option = PR_TASK_PERF_EVENTS_{EN,DIS}ABLE).
- the 'owner' of the event object, typically the file descriptor.
Currently these two concepts are conflated, which gives trouble with
scm_rights passing of file descriptors. Passing the event and then
closing the creating task would render the event 'orphan' and would
have it cleared out. Unlikely what is expectd.
This patch untangles these two concepts by using PERF_EVENT_STATE_EXIT
to denote the second type.
Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In preparation to adding more options, convert the boolean argument
into a flags word.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sync_child_event() has outgrown its purpose, it does far too much.
Bring it back to its named purpose.
Rename __perf_event_exit_task() to perf_event_exit_event() to better
reflect what it does and move the event->state assignment under the
ctx->lock, like state changes ought to be.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use smp_store_release() to clear event->owner and
lockless_dereference() to observe it. Further use READ_ONCE() for all
lockless reads.
This changes perf_remove_from_owner() to leave event->owner cleared.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We should never attempt to enable a STATE_EXIT event.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is but a single caller, remove the function - we already have
_free_event(), the extra indirection is nonsensical..
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is a race between perf_event_exit_task_context() and
orphans_remove_work() which results in a use-after-free.
We mark ctx->task with TASK_TOMBSTONE to indicate a context is
'dead', under ctx->lock. After which point event_function_call()
on any event of that context will NOP
A concurrent orphans_remove_work() will only hold ctx->mutex for
the list iteration and not serialize against this. Therefore its
possible that orphans_remove_work()'s perf_remove_from_context()
call will fail, but we'll continue to free the event, with the
result of free'd memory still being on lists and everything.
Once perf_event_exit_task_context() gets around to acquiring
ctx->mutex it too will iterate the event list, encounter the
already free'd event and proceed to free it _again_. This fails
with the WARN in free_event().
Plug the race by having perf_event_exit_task_context() hold
ctx::mutex over the whole tear-down, thereby 'naturally'
serializing against all other sites, including the orphan work.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: alexander.shishkin@linux.intel.com
Cc: dsahern@gmail.com
Cc: namhyung@kernel.org
Link: http://lkml.kernel.org/r/20160125130954.GY6357@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We should set event->owner before we install the event,
otherwise there is a hole where the target task can fork() and
we'll not inherit the event because it thinks the event is
orphaned.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).
Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We are currently using asynchronous deallocation in the error path in
AUX mmap code, which is unnecessary and also presents a problem for users
that wish to probe for the biggest possible buffer size they can get:
they'll get -EINVAL on all subsequent attemts to allocate a smaller
buffer before the asynchronous deallocation callback frees up the pages
from the previous unsuccessful attempt.
Currently, gdb does that for allocating AUX buffers for Intel PT traces.
More specifically, overwrite mode of AUX pmus that don't support hardware
sg (some implementations of Intel PT, for instance) is limited to only
one contiguous high order allocation for its buffer and there is no way
of knowing its size without trying.
This patch changes error path freeing to be synchronous as there won't
be any contenders for the AUX pages at that point.
Reported-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/1453216469-9509-1-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is a race against perf_event_exit_task() vs
event_function_call(),find_get_context(),perf_install_in_context()
(iow, everyone).
Since there is no permanent marker on a context that its dead, it is
quite possible that we access (and even modify) a context after its
passed through perf_event_exit_task().
For instance, find_get_context() might find the context still
installed, but by the time we get to perf_install_in_context() it
might already have passed through perf_event_exit_task() and be
considered dead, we will however still add the event to it.
Solve this by marking a ctx dead by setting its ctx->task value to -1,
it must be !0 so we still know its a (former) task context.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is one common bug left in all the event_function_call() users,
between loading ctx->task and getting to the remote_function(),
ctx->task can already have been changed.
Therefore we need to double check and retry if ctx->task != current.
Insert another trampoline specific to event_function_call() that
checks for this and further validates state. This also allows getting
rid of the active/inactive functions.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The perf_remove_from_context() usage in __perf_event_exit_task() is
different from the other usages in that this site has already
detached and scheduled out the task context.
This will stand in the way of stronger assertions checking the (task)
context scheduling invariants.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is a very nasty problem wrt disabling the perf task scheduling
hooks.
Currently we {set,clear} ctx->is_active on every
__perf_event_task_sched_{in,out}, _however_ this means that if we
disable these calls we'll have task contexts with ->is_active set that
are not active and 'active' task contexts without ->is_active set.
This can result in event_function_call() looping on the ctx->is_active
condition basically indefinitely.
Resolve this by changing things such that contexts without events do
not set ->is_active like we used to. From this invariant it trivially
follows that if there are no (task) events, every task ctx is inactive
and disabling the context switch hooks is harmless.
This leaves two places that need attention (and already had
accumulated weird and wonderful hacks to work around, without
recognising this actual problem).
Namely:
- perf_install_in_context() will need to deal with installing events
in an inactive context, meaning it cannot rely on ctx-is_active for
its IPIs.
- perf_remove_from_context() will have to mark a context as inactive
when it removes the last event.
For specific detail, see the patch/comments.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
For no apparent reason and to great confusion the rules for
ctx->is_active and cpuctx->task_ctx are different. This means that its
not always possible to find all active (task) contexts.
Fix this such that if ctx->is_active gets set, we also set (or verify)
cpuctx->task_ctx.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It doesn't make sense to take up-to _4_ references on
perf_sched_events() per event, avoid doing this.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Like perf_enable_on_exec(), perf_event_enable() event scheduling has problems
respecting the context hierarchy when trying to schedule events (for
example, it will try and add a pinned event without first removing
existing flexible events).
So simplify it by using the new ctx_resched() call which will DTRT.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We have a function that does exactly what we want here, use it. This
reduces the amount of cpuctx->task_ctx muckery.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There are two problems with the current perf_enable_on_exec() event
scheduling:
- the newly enabled events will be immediately scheduled
irrespective of their ctx event list order.
- there's a hole in the ctx->lock between scheduling the events
out and putting them back on.
Esp. the latter issue is a real problem because a hole in event
scheduling leaves the thing in an observable inconsistent state,
confusing things.
Fix both issues by first doing the enable iteration and at the end,
when there are newly enabled events, reschedule the ctx in one go.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The comment here is horribly out of date, remove it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is a comment that states that perf_event_context_sched_in() will
also switch in the cgroup events, I cannot find it does so. Therefore
all the resulting logic goes out the window too.
Clean that up.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There appears to be a problem in __perf_event_task_sched_in() wrt
cgroup event scheduling.
The normal event scheduling order is:
CPU pinned
Task pinned
CPU flexible
Task flexible
And since perf_cgroup_sched*() only schedules the cpu context, we must
call this _before_ adding the task events.
Note: double check what happens on the ctx switch optimization where
the task ctx isn't scheduled.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
By checking the effective credentials instead of the real UID / permitted
capabilities, ensure that the calling process actually intended to use its
credentials.
To ensure that all ptrace checks use the correct caller credentials (e.g.
in case out-of-tree code or newly added code omits the PTRACE_MODE_*CREDS
flag), use two new flags and require one of them to be set.
The problem was that when a privileged task had temporarily dropped its
privileges, e.g. by calling setreuid(0, user_uid), with the intent to
perform following syscalls with the credentials of a user, it still passed
ptrace access checks that the user would not be able to pass.
While an attacker should not be able to convince the privileged task to
perform a ptrace() syscall, this is a problem because the ptrace access
check is reused for things in procfs.
In particular, the following somewhat interesting procfs entries only rely
on ptrace access checks:
/proc/$pid/stat - uses the check for determining whether pointers
should be visible, useful for bypassing ASLR
/proc/$pid/maps - also useful for bypassing ASLR
/proc/$pid/cwd - useful for gaining access to restricted
directories that contain files with lax permissions, e.g. in
this scenario:
lrwxrwxrwx root root /proc/13020/cwd -> /root/foobar
drwx------ root root /root
drwxr-xr-x root root /root/foobar
-rw-r--r-- root root /root/foobar/secret
Therefore, on a system where a root-owned mode 6755 binary changes its
effective credentials as described and then dumps a user-specified file,
this could be used by an attacker to reveal the memory layout of root's
processes or reveal the contents of files he is not allowed to access
(through /proc/$pid/cwd).
[akpm@linux-foundation.org: fix warning]
Signed-off-by: Jann Horn <jann@thejh.net>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: "Serge E. Hallyn" <serge.hallyn@ubuntu.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As with rmap, with new refcounting we cannot rely on PageTransHuge() to
check if we need to charge size of huge page form the cgroup. We need
to get information from caller to know whether it was mapped with PMD or
PTE.
We do uncharge when last reference on the page gone. At that point if
we see PageTransHuge() it means we need to unchange whole huge page.
The tricky part is partial unmap -- when we try to unmap part of huge
page. We don't do a special handing of this situation, meaning we don't
uncharge the part of huge page unless last user is gone or
split_huge_page() is triggered. In case of cgroup memory pressure
happens the partial unmapped page will be split through shrinker. This
should be good enough.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We're going to allow mapping of individual 4k pages of THP compound
page. It means we cannot rely on PageTransHuge() check to decide if
map/unmap small page or THP.
The patch adds new argument to rmap functions to indicate whether we
want to operate on whole compound page or only the small page.
[n-horiguchi@ah.jp.nec.com: fix mapcount mismatch in hugepage migration]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently looking at /proc/<pid>/status or statm, there is no way to
distinguish shmem pages from pages mapped to a regular file (shmem pages
are mapped to /dev/zero), even though their implication in actual memory
use is quite different.
The internal accounting currently counts shmem pages together with
regular files. As a preparation to extend the userspace interfaces,
this patch adds MM_SHMEMPAGES counter to mm_rss_stat to account for
shmem pages separately from MM_FILEPAGES. The next patch will expose it
to userspace - this patch doesn't change the exported values yet, by
adding up MM_SHMEMPAGES to MM_FILEPAGES at places where MM_FILEPAGES was
used before. The only user-visible change after this patch is the OOM
killer message that separates the reported "shmem-rss" from "file-rss".
[vbabka@suse.cz: forward-porting, tweak changelog]
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch collapses the two 'hard' cases, which are
perf_event_{dis,en}able().
I cannot seem to convince myself the current code is correct.
So starting with perf_event_disable(); we don't strictly need to test
for event->state == ACTIVE, ctx->is_active is enough. If the event is
not scheduled while the ctx is, __perf_event_disable() still does the
right thing. Its a little less efficient to IPI in that case,
over-all simpler.
For perf_event_enable(); the same goes, but I think that's actually
broken in its current form. The current condition is: ctx->is_active
&& event->state == OFF, that means it doesn't do anything when
!ctx->active && event->state == OFF. This is wrong, it should still
mark the event INACTIVE in that case, otherwise we'll still not try
and schedule the event once the context becomes active again.
This patch implements the two function using the new
event_function_call() and does away with the tricky event->state
tests.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There's a race on CPU unplug where we free the swevent hash array
while it can still have events on. This will result in a
use-after-free which is BAD.
Simply do not free the hash array on unplug. This leaves the thing
around and no use-after-free takes place.
When the last swevent dies, we do a for_each_possible_cpu() iteration
anyway to clean these up, at which time we'll free it, so no leakage
will occur.
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull cgroup fixes from Tejun Heo:
"More change than I'd have liked at this stage. The pids controller
and the changes made to cgroup core to support it introduced and
revealed several important issues.
- Assigning membership to a newly created task and migrating it can
race leading to incorrect accounting. Oleg fixed it by widening
threadgroup synchronization. It looks like we'll be able to merge
it with a different percpu rwsem which is used in fork path making
things simpler and cheaper.
- The recent change to extend cgroup membership to zombies (so that
pid accounting can extend till the pid is actually released) missed
pinning the underlying data structures leading to use-after-free.
Fixed.
- v2 hierarchy was calling subsystem callbacks with the wrong target
cgroup_subsys_state based on the incorrect assumption that they
share the same target. pids is the first controller affected by
this. Subsys callbacks updated so that they can deal with
multi-target migrations"
* 'for-4.4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup_pids: don't account for the root cgroup
cgroup: fix handling of multi-destination migration from subtree_control enabling
cgroup_freezer: simplify propagation of CGROUP_FROZEN clearing in freezer_attach()
cgroup: pids: kill pids_fork(), simplify pids_can_fork() and pids_cancel_fork()
cgroup: pids: fix race between cgroup_post_fork() and cgroup_migrate()
cgroup: make css_set pin its css's to avoid use-afer-free
cgroup: fix cftype->file_offset handling
Various functions implement the same pattern to send IPIs to an
event's CPU. Collapse the easy ones in a common helper function to
reduce duplication.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In case we monitor events system wide, we get EXIT event
(when configured) twice for each task that exited.
Note doubled lines with same pid/tid in following example:
$ sudo ./perf record -a
^C[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.480 MB perf.data (2518 samples) ]
$ sudo ./perf report -D | grep EXIT
0 60290687567581 0x59910 [0x38]: PERF_RECORD_EXIT(1250:1250):(1250:1250)
0 60290687568354 0x59948 [0x38]: PERF_RECORD_EXIT(1250:1250):(1250:1250)
0 60290687988744 0x59ad8 [0x38]: PERF_RECORD_EXIT(1250:1250):(1250:1250)
0 60290687989198 0x59b10 [0x38]: PERF_RECORD_EXIT(1250:1250):(1250:1250)
1 60290692567895 0x62af0 [0x38]: PERF_RECORD_EXIT(1253:1253):(1253:1253)
1 60290692568322 0x62b28 [0x38]: PERF_RECORD_EXIT(1253:1253):(1253:1253)
2 60290692739276 0x69a18 [0x38]: PERF_RECORD_EXIT(1252:1252):(1252:1252)
2 60290692739910 0x69a50 [0x38]: PERF_RECORD_EXIT(1252:1252):(1252:1252)
The reason is that the cpu contexts are processes each time
we call perf_event_task. I'm changing the perf_event_aux logic
to serve task_ctx and cpu contexts separately, which ensure we
don't get EXIT event generated twice on same cpu context.
This does not affect other auxiliary events, as they don't
use task_ctx at all.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/1446649205-5822-1-git-send-email-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Consider the following v2 hierarchy.
P0 (+memory) --- P1 (-memory) --- A
\- B
P0 has memory enabled in its subtree_control while P1 doesn't. If
both A and B contain processes, they would belong to the memory css of
P1. Now if memory is enabled on P1's subtree_control, memory csses
should be created on both A and B and A's processes should be moved to
the former and B's processes the latter. IOW, enabling controllers
can cause atomic migrations into different csses.
The core cgroup migration logic has been updated accordingly but the
controller migration methods haven't and still assume that all tasks
migrate to a single target css; furthermore, the methods were fed the
css in which subtree_control was updated which is the parent of the
target csses. pids controller depends on the migration methods to
move charges and this made the controller attribute charges to the
wrong csses often triggering the following warning by driving a
counter negative.
WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40()
Modules linked in:
CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29
...
ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000
ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00
ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8
Call Trace:
[<ffffffff81551ffc>] dump_stack+0x4e/0x82
[<ffffffff810de202>] warn_slowpath_common+0x82/0xc0
[<ffffffff810de2fa>] warn_slowpath_null+0x1a/0x20
[<ffffffff8118e031>] pids_cancel.constprop.6+0x31/0x40
[<ffffffff8118e0fd>] pids_can_attach+0x6d/0xf0
[<ffffffff81188a4c>] cgroup_taskset_migrate+0x6c/0x330
[<ffffffff81188e05>] cgroup_migrate+0xf5/0x190
[<ffffffff81189016>] cgroup_attach_task+0x176/0x200
[<ffffffff8118949d>] __cgroup_procs_write+0x2ad/0x460
[<ffffffff81189684>] cgroup_procs_write+0x14/0x20
[<ffffffff811854e5>] cgroup_file_write+0x35/0x1c0
[<ffffffff812e26f1>] kernfs_fop_write+0x141/0x190
[<ffffffff81265f88>] __vfs_write+0x28/0xe0
[<ffffffff812666fc>] vfs_write+0xac/0x1a0
[<ffffffff81267019>] SyS_write+0x49/0xb0
[<ffffffff81bcef32>] entry_SYSCALL_64_fastpath+0x12/0x76
This patch fixes the bug by removing @css parameter from the three
migration methods, ->can_attach, ->cancel_attach() and ->attach() and
updating cgroup_taskset iteration helpers also return the destination
css in addition to the task being migrated. All controllers are
updated accordingly.
* Controllers which don't care whether there are one or multiple
target csses can be converted trivially. cpu, io, freezer, perf,
netclassid and netprio fall in this category.
* cpuset's current implementation assumes that there's single source
and destination and thus doesn't support v2 hierarchy already. The
only change made by this patchset is how that single destination css
is obtained.
* memory migration path already doesn't do anything on v2. How the
single destination css is obtained is updated and the prep stage of
mem_cgroup_can_attach() is reordered to accomodate the change.
* pids is the only controller which was affected by this bug. It now
correctly handles multi-destination migrations and no longer causes
counter underflow from incorrect accounting.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Aleksa Sarai <cyphar@cyphar.com>
There were still a number of references to my old Red Hat email
address in the kernel source. Remove these while keeping the
Red Hat copyright notices intact.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch reinforces the lockdep checks performed by
perf_cgroup_from_tsk() by passing the perf_event_context
whenever possible. It is okay to not hold the RCU read lock
when we know we hold the ctx->lock. This patch makes sure this
property holds.
In some functions, such as perf_cgroup_sched_in(), we do not
pass the context because we are sure we are holding the RCU
read lock.
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: edumazet@google.com
Link: http://lkml.kernel.org/r/1447322404-10920-3-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The RCU checker detected RCU violation in the cgroup switching routines
perf_cgroup_sched_in() and perf_cgroup_sched_out(). We were dereferencing
cgroup from task without holding the RCU lock.
Fix this by holding the RCU read lock. We move the locking from
perf_cgroup_switch() to avoid double locking.
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: edumazet@google.com
Link: http://lkml.kernel.org/r/1447322404-10920-2-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull perf updates from Thomas Gleixner:
"Mostly updates to the perf tool plus two fixes to the kernel core code:
- Handle tracepoint filters correctly for inherited events (Peter
Zijlstra)
- Prevent a deadlock in perf_lock_task_context (Paul McKenney)
- Add missing newlines to some pr_err() calls (Arnaldo Carvalho de
Melo)
- Print full source file paths when using 'perf annotate --print-line
--full-paths' (Michael Petlan)
- Fix 'perf probe -d' when just one out of uprobes and kprobes is
enabled (Wang Nan)
- Add compiler.h to list.h to fix 'make perf-tar-src-pkg' generated
tarballs, i.e. out of tree building (Arnaldo Carvalho de Melo)
- Add the llvm-src-base.c and llvm-src-kbuild.c files, generated by
the 'perf test' LLVM entries, when running it in-tree, to
.gitignore (Yunlong Song)
- libbpf error reporting improvements, using a strerror interface to
more precisely tell the user about problems with the provided
scriptlet, be it in C or as a ready made object file (Wang Nan)
- Do not be case sensitive when searching for matching 'perf test'
entries (Arnaldo Carvalho de Melo)
- Inform the user about objdump failures in 'perf annotate' (Andi
Kleen)
- Improve the LLVM 'perf test' entry, introduce a new ones for BPF
and kbuild tests to check the environment used by clang to compile
.c scriptlets (Wang Nan)"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
perf/x86/intel/rapl: Remove the unused RAPL_EVENT_DESC() macro
tools include: Add compiler.h to list.h
perf probe: Verify parameters in two functions
perf session: Add missing newlines to some pr_err() calls
perf annotate: Support full source file paths for srcline fix
perf test: Add llvm-src-base.c and llvm-src-kbuild.c to .gitignore
perf: Fix inherited events vs. tracepoint filters
perf: Disable IRQs across RCU RS CS that acquires scheduler lock
perf test: Do not be case sensitive when searching for matching tests
perf test: Add 'perf test BPF'
perf test: Enhance the LLVM tests: add kbuild test
perf test: Enhance the LLVM test: update basic BPF test program
perf bpf: Improve BPF related error messages
perf tools: Make fetch_kernel_version() publicly available
bpf tools: Add new API bpf_object__get_kversion()
bpf tools: Improve libbpf error reporting
perf probe: Cleanup find_perf_probe_point_from_map to reduce redundancy
perf annotate: Inform the user about objdump failures in --stdio
perf stat: Make stat options global
perf sched latency: Fix thread pid reuse issue
...
Arnaldo reported that tracepoint filters seem to misbehave (ie. not
apply) on inherited events.
The fix is obvious; filters are only set on the actual (parent)
event, use the normal pattern of using this parent event for filters.
This is safe because each child event has a reference to it.
Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20151102095051.GN17308@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The perf_lock_task_context() function disables preemption across its
RCU read-side critical section because that critical section acquires
a scheduler lock. If there was a preemption during that RCU read-side
critical section, the rcu_read_unlock() could attempt to acquire scheduler
locks, resulting in deadlock.
However, recent optimizations to expedited grace periods mean that IPI
handlers that execute during preemptible RCU read-side critical sections
can now cause the subsequent rcu_read_unlock() to acquire scheduler locks.
Disabling preemption does nothiing to prevent these IPI handlers from
executing, so these optimizations introduced a deadlock. In theory,
this deadlock could be avoided by pulling all wakeups and printk()s out
from rnp->lock critical sections, but in practice this would re-introduce
some RCU CPU stall warning bugs.
Given that acquiring scheduler locks entails disabling interrupts, these
deadlocks can be avoided by disabling interrupts (instead of disabling
preemption) across any RCU read-side critical that acquires scheduler
locks and holds them across the rcu_read_unlock(). This commit therefore
makes this change for perf_lock_task_context().
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Stephane Eranian <eranian@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20151104134838.GR29027@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull cgroup updates from Tejun Heo:
"The cgroup core saw several significant updates this cycle:
- percpu_rwsem for threadgroup locking is reinstated. This was
temporarily dropped due to down_write latency issues. Oleg's
rework of percpu_rwsem which is scheduled to be merged in this
merge window resolves the issue.
- On the v2 hierarchy, when controllers are enabled and disabled, all
operations are atomic and can fail and revert cleanly. This allows
->can_attach() failure which is necessary for cpu RT slices.
- Tasks now stay associated with the original cgroups after exit
until released. This allows tracking resources held by zombies
(e.g. pids) and makes it easy to find out where zombies came from
on the v2 hierarchy. The pids controller was broken before these
changes as zombies escaped the limits; unfortunately, updating this
behavior required too many invasive changes and I don't think it's
a good idea to backport them, so the pids controller on 4.3, the
first version which included the pids controller, will stay broken
at least until I'm sure about the cgroup core changes.
- Optimization of a couple common tests using static_key"
* 'for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (38 commits)
cgroup: fix race condition around termination check in css_task_iter_next()
blkcg: don't create "io.stat" on the root cgroup
cgroup: drop cgroup__DEVEL__legacy_files_on_dfl
cgroup: replace error handling in cgroup_init() with WARN_ON()s
cgroup: add cgroup_subsys->free() method and use it to fix pids controller
cgroup: keep zombies associated with their original cgroups
cgroup: make css_set_rwsem a spinlock and rename it to css_set_lock
cgroup: don't hold css_set_rwsem across css task iteration
cgroup: reorganize css_task_iter functions
cgroup: factor out css_set_move_task()
cgroup: keep css_set and task lists in chronological order
cgroup: make cgroup_destroy_locked() test cgroup_is_populated()
cgroup: make css_sets pin the associated cgroups
cgroup: relocate cgroup_[try]get/put()
cgroup: move check_for_release() invocation
cgroup: replace cgroup_has_tasks() with cgroup_is_populated()
cgroup: make cgroup->nr_populated count the number of populated css_sets
cgroup: remove an unused parameter from cgroup_task_migrate()
cgroup: fix too early usage of static_branch_disable()
cgroup: make cgroup_update_dfl_csses() migrate all target processes atomically
...
Pull networking updates from David Miller:
Changes of note:
1) Allow to schedule ICMP packets in IPVS, from Alex Gartrell.
2) Provide FIB table ID in ipv4 route dumps just as ipv6 does, from
David Ahern.
3) Allow the user to ask for the statistics to be filtered out of
ipv4/ipv6 address netlink dumps. From Sowmini Varadhan.
4) More work to pass the network namespace context around deep into
various packet path APIs, starting with the netfilter hooks. From
Eric W Biederman.
5) Add layer 2 TX/RX checksum offloading to qeth driver, from Thomas
Richter.
6) Use usec resolution for SYN/ACK RTTs in TCP, from Yuchung Cheng.
7) Support Very High Throughput in wireless MESH code, from Bob
Copeland.
8) Allow setting the ageing_time in switchdev/rocker. From Scott
Feldman.
9) Properly autoload L2TP type modules, from Stephen Hemminger.
10) Fix and enable offload features by default in 8139cp driver, from
David Woodhouse.
11) Support both ipv4 and ipv6 sockets in a single vxlan device, from
Jiri Benc.
12) Fix CWND limiting of thin streams in TCP, from Bendik Rønning
Opstad.
13) Fix IPSEC flowcache overflows on large systems, from Steffen
Klassert.
14) Convert bridging to track VLANs using rhashtable entries rather than
a bitmap. From Nikolay Aleksandrov.
15) Make TCP listener handling completely lockless, this is a major
accomplishment. Incoming request sockets now live in the
established hash table just like any other socket too.
From Eric Dumazet.
15) Provide more bridging attributes to netlink, from Nikolay
Aleksandrov.
16) Use hash based algorithm for ipv4 multipath routing, this was very
long overdue. From Peter Nørlund.
17) Several y2038 cures, mostly avoiding timespec. From Arnd Bergmann.
18) Allow non-root execution of EBPF programs, from Alexei Starovoitov.
19) Support SO_INCOMING_CPU as setsockopt, from Eric Dumazet. This
influences the port binding selection logic used by SO_REUSEPORT.
20) Add ipv6 support to VRF, from David Ahern.
21) Add support for Mellanox Spectrum switch ASIC, from Jiri Pirko.
22) Add rtl8xxxu Realtek wireless driver, from Jes Sorensen.
23) Implement RACK loss recovery in TCP, from Yuchung Cheng.
24) Support multipath routes in MPLS, from Roopa Prabhu.
25) Fix POLLOUT notification for listening sockets in AF_UNIX, from Eric
Dumazet.
26) Add new QED Qlogic river, from Yuval Mintz, Manish Chopra, and
Sudarsana Kalluru.
27) Don't fetch timestamps on AF_UNIX sockets, from Hannes Frederic
Sowa.
28) Support ipv6 geneve tunnels, from John W Linville.
29) Add flood control support to switchdev layer, from Ido Schimmel.
30) Fix CHECKSUM_PARTIAL handling of potentially fragmented frames, from
Hannes Frederic Sowa.
31) Support persistent maps and progs in bpf, from Daniel Borkmann.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1790 commits)
sh_eth: use DMA barriers
switchdev: respect SKIP_EOPNOTSUPP flag in case there is no recursion
net: sched: kill dead code in sch_choke.c
irda: Delete an unnecessary check before the function call "irlmp_unregister_service"
net: dsa: mv88e6xxx: include DSA ports in VLANs
net: dsa: mv88e6xxx: disable SA learning for DSA and CPU ports
net/core: fix for_each_netdev_feature
vlan: Invoke driver vlan hooks only if device is present
arcnet/com20020: add LEDS_CLASS dependency
bpf, verifier: annotate verbose printer with __printf
dp83640: Only wait for timestamps for packets with timestamping enabled.
ptp: Change ptp_class to a proper bitmask
dp83640: Prune rx timestamp list before reading from it
dp83640: Delay scheduled work.
dp83640: Include hash in timestamp/packet matching
ipv6: fix tunnel error handling
net/mlx5e: Fix LSO vlan insertion
net/mlx5e: Re-eanble client vlan TX acceleration
net/mlx5e: Return error in case mlx5e_set_features() fails
net/mlx5e: Don't allow more than max supported channels
...
Pull perf updates from Ingo Molnar:
"Kernel side changes:
- Improve accuracy of perf/sched clock on x86. (Adrian Hunter)
- Intel DS and BTS updates. (Alexander Shishkin)
- Intel cstate PMU support. (Kan Liang)
- Add group read support to perf_event_read(). (Peter Zijlstra)
- Branch call hardware sampling support, implemented on x86 and
PowerPC. (Stephane Eranian)
- Event groups transactional interface enhancements. (Sukadev
Bhattiprolu)
- Enable proper x86/intel/uncore PMU support on multi-segment PCI
systems. (Taku Izumi)
- ... misc fixes and cleanups.
The perf tooling team was very busy again with 200+ commits, the full
diff doesn't fit into lkml size limits. Here's an (incomplete) list
of the tooling highlights:
New features:
- Change the default event used in all tools (record/top): use the
most precise "cycles" hw counter available, i.e. when the user
doesn't specify any event, it will try using cycles:ppp, cycles:pp,
etc and fall back transparently until it finds a working counter.
(Arnaldo Carvalho de Melo)
- Integration of perf with eBPF that, given an eBPF .c source file
(or .o file built for the 'bpf' target with clang), will get it
automatically built, validated and loaded into the kernel via the
sys_bpf syscall, which can then be used and seen using 'perf trace'
and other tools.
(Wang Nan)
Various user interface improvements:
- Automatic pager invocation on long help output. (Namhyung Kim)
- Search for more options when passing args to -h, e.g.: (Arnaldo
Carvalho de Melo)
$ perf report -h interface
Usage: perf report [<options>]
--gtk Use the GTK2 interface
--stdio Use the stdio interface
--tui Use the TUI interface
- Show ordered command line options when -h is used or when an
unknown option is specified. (Arnaldo Carvalho de Melo)
- If options are passed after -h, show just its descriptions, not all
options. (Arnaldo Carvalho de Melo)
- Implement column based horizontal scrolling in the hists browser
(top, report), making it possible to use the TUI for things like
'perf mem report' where there are many more columns than can fit in
a terminal. (Arnaldo Carvalho de Melo)
- Enhance the error reporting of tracepoint event parsing, e.g.:
$ oldperf record -e sched:sched_switc usleep 1
event syntax error: 'sched:sched_switc'
\___ unknown tracepoint
Run 'perf list' for a list of valid events
Now we get the much nicer:
$ perf record -e sched:sched_switc ls
event syntax error: 'sched:sched_switc'
\___ can't access trace events
Error: No permissions to read /sys/kernel/debug/tracing/events/sched/sched_switc
Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/debug'
And after we have those mount point permissions fixed:
$ perf record -e sched:sched_switc ls
event syntax error: 'sched:sched_switc'
\___ unknown tracepoint
Error: File /sys/kernel/debug/tracing/events/sched/sched_switc not found.
Hint: Perhaps this kernel misses some CONFIG_ setting to enable this feature?.
I.e. basically now the event parsing routing uses the strerror_open()
routines introduced by and used in 'perf trace' work. (Jiri Olsa)
- Fail properly when pattern matching fails to find a tracepoint,
i.e. '-e non:existent' was being correctly handled, with a proper
error message about that not being a valid event, but '-e
non:existent*' wasn't, fix it. (Jiri Olsa)
- Do event name substring search as last resort in 'perf list'.
(Arnaldo Carvalho de Melo)
E.g.:
# perf list clock
List of pre-defined events (to be used in -e):
cpu-clock [Software event]
task-clock [Software event]
uncore_cbox_0/clockticks/ [Kernel PMU event]
uncore_cbox_1/clockticks/ [Kernel PMU event]
kvm:kvm_pvclock_update [Tracepoint event]
kvm:kvm_update_master_clock [Tracepoint event]
power:clock_disable [Tracepoint event]
power:clock_enable [Tracepoint event]
power:clock_set_rate [Tracepoint event]
syscalls:sys_enter_clock_adjtime [Tracepoint event]
syscalls:sys_enter_clock_getres [Tracepoint event]
syscalls:sys_enter_clock_gettime [Tracepoint event]
syscalls:sys_enter_clock_nanosleep [Tracepoint event]
syscalls:sys_enter_clock_settime [Tracepoint event]
syscalls:sys_exit_clock_adjtime [Tracepoint event]
syscalls:sys_exit_clock_getres [Tracepoint event]
syscalls:sys_exit_clock_gettime [Tracepoint event]
syscalls:sys_exit_clock_nanosleep [Tracepoint event]
syscalls:sys_exit_clock_settime [Tracepoint event]
Intel PT hardware tracing enhancements:
- Accept a zero --itrace period, meaning "as often as possible". In
the case of Intel PT that is the same as a period of 1 and a unit
of 'instructions' (i.e. --itrace=i1i). (Adrian Hunter)
- Harmonize itrace's synthesized callchains with the existing
--max-stack tool option. (Adrian Hunter)
- Allow time to be displayed in nanoseconds in 'perf script'.
(Adrian Hunter)
- Fix potential infinite loop when handling Intel PT timestamps.
(Adrian Hunter)
- Slighly improve Intel PT debug logging. (Adrian Hunter)
- Warn when AUX data has been lost, just like when processing
PERF_RECORD_LOST. (Adrian Hunter)
- Further document export-to-postgresql.py script. (Adrian Hunter)
- Add option to synthesize branch stack from auxtrace data. (Adrian
Hunter)
Misc notable changes:
- Switch the default callchain output mode to 'graph,0.5,caller', to
make it look like the default for other tools, reducing the
learning curve for people used to 'caller' based viewing. (Arnaldo
Carvalho de Melo)
- various call chain usability enhancements. (Namhyung Kim)
- Introduce the 'P' event modifier, meaning 'max precision level,
please', i.e.:
$ perf record -e cycles:P usleep 1
Is now similar to:
$ perf record usleep 1
Useful, for instance, when specifying multiple events. (Jiri Olsa)
- Add 'socket' sort entry, to sort by the processor socket in 'perf
top' and 'perf report'. (Kan Liang)
- Introduce --socket-filter to 'perf report', for filtering by
processor socket. (Kan Liang)
- Add new "Zoom into Processor Socket" operation in the perf hists
browser, used in 'perf top' and 'perf report'. (Kan Liang)
- Allow probing on kmodules without DWARF. (Masami Hiramatsu)
- Fix 'perf probe -l' for probes added to kernel module functions.
(Masami Hiramatsu)
- Preparatory work for the 'perf stat record' feature that will allow
generating perf.data files with counting data in addition to the
sampling mode we have now (Jiri Olsa)
- Update libtraceevent KVM plugin. (Paolo Bonzini)
- ... plus lots of other enhancements that I failed to list properly,
by: Adrian Hunter, Alexander Shishkin, Andi Kleen, Andrzej Hajda,
Arnaldo Carvalho de Melo, Dima Kogan, Don Zickus, Geliang Tang, He
Kuang, Huaitong Han, Ingo Molnar, Jan Stancek, Jiri Olsa, Kan
Liang, Kirill Tkhai, Masami Hiramatsu, Matt Fleming, Namhyung Kim,
Paolo Bonzini, Peter Zijlstra, Rabin Vincent, Scott Wood, Stephane
Eranian, Sukadev Bhattiprolu, Taku Izumi, Vaishali Thakkar, Wang
Nan, Yang Shi and Yunlong Song"
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (260 commits)
perf unwind: Pass symbol source to libunwind
tools build: Fix libiberty feature detection
perf tools: Compile scriptlets to BPF objects when passing '.c' to --event
perf record: Add clang options for compiling BPF scripts
perf bpf: Attach eBPF filter to perf event
perf tools: Make sure fixdep is built before libbpf
perf script: Enable printing of branch stack
perf trace: Add cmd string table to decode sys_bpf first arg
perf bpf: Collect perf_evsel in BPF object files
perf tools: Load eBPF object into kernel
perf tools: Create probe points for BPF programs
perf tools: Enable passing bpf object file to --event
perf ebpf: Add the libbpf glue
perf tools: Make perf depend on libbpf
perf symbols: Fix endless loop in dso__split_kallsyms_for_kcore
perf tools: Enable pre-event inherit setting by config terms
perf symbols: we can now read separate debug-info files based on a build ID
perf symbols: Fix type error when reading a build-id
perf tools: Search for more options when passing args to -h
perf stat: Cache aggregated map entries in extra cpumap
...
This seems to be a mis-reading of how alpha memory ordering works, and
is not backed up by the alpha architecture manual. The helper functions
don't do anything special on any other architectures, and the arguments
that support them being safe on other architectures also argue that they
are safe on alpha.
Basically, the "control dependency" is between a previous read and a
subsequent write that is dependent on the value read. Even if the
subsequent write is actually done speculatively, there is no way that
such a speculative write could be made visible to other cpu's until it
has been committed, which requires validating the speculation.
Note that most weakely ordered architectures (very much including alpha)
do not guarantee any ordering relationship between two loads that depend
on each other on a control dependency:
read A
if (val == 1)
read B
because the conditional may be predicted, and the "read B" may be
speculatively moved up to before reading the value A. So we require the
user to insert a smp_rmb() between the two accesses to be correct:
read A;
if (A == 1)
smp_rmb()
read B
Alpha is further special in that it can break that ordering even if the
*address* of B depends on the read of A, because the cacheline that is
read later may be stale unless you have a memory barrier in between the
pointer read and the read of the value behind a pointer:
read ptr
read offset(ptr)
whereas all other weakly ordered architectures guarantee that the data
dependency (as opposed to just a control dependency) will order the two
accesses. As a result, alpha needs a "smp_read_barrier_depends()" in
between those two reads for them to be ordered.
The coontrol dependency that "READ_ONCE_CTRL()" and "atomic_read_ctrl()"
had was a control dependency to a subsequent *write*, however, and
nobody can finalize such a subsequent write without having actually done
the read. And were you to write such a value to a "stale" cacheline
(the way the unordered reads came to be), that would seem to lose the
write entirely.
So the things that make alpha able to re-order reads even more
aggressively than other weak architectures do not seem to be relevant
for a subsequent write. Alpha memory ordering may be strange, but
there's no real indication that it is *that* strange.
Also, the alpha architecture reference manual very explicitly talks
about the definition of "Dependence Constraints" in section 5.6.1.7,
where a preceding read dominates a subsequent write.
Such a dependence constraint admittedly does not impose a BEFORE (alpha
architecture term for globally visible ordering), but it does guarantee
that there can be no "causal loop". I don't see how you could avoid
such a loop if another cpu could see the stored value and then impact
the value of the first read. Put another way: the read and the write
could not be seen as being out of order wrt other cpus.
So I do not see how these "x_ctrl()" functions can currently be necessary.
I may have to eat my words at some point, but in the absense of clear
proof that alpha actually needs this, or indeed even an explanation of
how alpha could _possibly_ need it, I do not believe these functions are
called for.
And if it turns out that alpha really _does_ need a barrier for this
case, that barrier still should not be "smp_read_barrier_depends()".
We'd have to make up some new speciality barrier just for alpha, along
with the documentation for why it really is necessary.
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul E McKenney <paulmck@us.ibm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Instead of WARN_ON in perf_event_output() on unpaded raw samples,
pad them automatically.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
cgroup_exit() is called when a task exits and disassociates the
exiting task from its cgroups and half-attach it to the root cgroup.
This is unnecessary and undesirable.
No controller actually needs an exiting task to be disassociated with
non-root cgroups. Both cpu and perf_event controllers update the
association to the root cgroup from their exit callbacks just to keep
consistent with the cgroup core behavior.
Also, this disassociation makes it difficult to track resources held
by zombies or determine where the zombies came from. Currently, pids
controller is completely broken as it uncharges on exit and zombies
always escape the resource restriction. With cgroup association being
reset on exit, fixing it is pretty painful.
There's no reason to reset cgroup membership on exit. The zombie can
be removed from its css_set so that it doesn't show up on
"cgroup.procs" and thus can't be migrated or interfere with cgroup
removal. It can still pin and point to the css_set so that its cgroup
membership is maintained. This patch makes cgroup core keep zombies
associated with their cgroups at the time of exit.
* Previous patches decoupled populated_cnt tracking from css_set
lifetime, so a dying task can be simply unlinked from its css_set
while pinning and pointing to the css_set. This keeps css_set
association from task side alive while hiding it from "cgroup.procs"
and populated_cnt tracking. The css_set reference is dropped when
the task_struct is freed.
* ->exit() callback no longer needs the css arguments as the
associated css never changes once PF_EXITING is set. Removed.
* cpu and perf_events controllers no longer need ->exit() callbacks.
There's no reason to explicitly switch away on exit. The final
schedule out is enough. The callbacks are removed.
* On traditional hierarchies, nothing changes. "/proc/PID/cgroup"
still reports "/" for all zombies. On the default hierarchy,
"/proc/PID/cgroup" keeps reporting the cgroup that the task belonged
to at the time of exit. If the cgroup gets removed before the task
is reaped, " (deleted)" is appended.
v2: Build brekage due to missing dummy cgroup_free() when
!CONFIG_CGROUP fixed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
There are two races with the current code:
- Another event can join the group and compute a larger header_size
concurrently, if the smaller store wins we'll have an incorrect
header_size set.
- We compute the header_size after the event becomes active,
therefore its possible to use the size before its computed.
Remedy the first by moving the computation inside the ctx::mutex lock,
and the second by placing it _before_ perf_install_in_context().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Vince reported that its possible to overflow the various size fields
and get weird stuff if you stick too many events in a group.
Put a lid on this by requiring the fixed record size not exceed 16k.
This is still a fair amount of events (silly amount really) and leaves
plenty room for callchains and stack dwarves while also avoiding
overflowing the u16 variables.
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The exclusive_event_installable() stuff only works because its
exclusive with the grouping bits.
Rework the code such that there is a sane place to error out before we
go do things we cannot undo.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Define a new PERF_PMU_TXN_READ interface to read a group of counters
at once.
pmu->start_txn() // Initialize before first event
for each event in group
pmu->read(event); // Queue each event to be read
rc = pmu->commit_txn() // Read/update all queued counters
Note that we use this interface with all PMUs. PMUs that implement this
interface use the ->read() operation to _queue_ the counters to be read
and use ->commit_txn() to actually read all the queued counters at once.
PMUs that don't implement PERF_PMU_TXN_READ ignore ->start_txn() and
->commit_txn() and continue to read counters one at a time.
Thanks to input from Peter Zijlstra.
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/1441336073-22750-9-git-send-email-sukadev@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When we implement the ability to read several counters at once (using
the PERF_PMU_TXN_READ transaction interface), perf_event_read() can
fail when the 'group' parameter is true (eg: trying to read too many
events at once).
For now, have perf_event_read() return an integer. Ignore the return
value when the 'group' parameter is false.
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/1441336073-22750-8-git-send-email-sukadev@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In order to enable the use of perf_event_read(.group = true), we need
to invert the sibling-child loop nesting of perf_read_group().
Currently we iterate the child list for each sibling, this precludes
using group reads. Flip things around so we iterate each group for
each child.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[ Made the patch compile and things. ]
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/1441336073-22750-7-git-send-email-sukadev@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Enable perf_event_read() to update entire groups at once, this will be
useful for read transactions.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20150723080435.GE25159@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
