Allow the developer to specifiy the initial value of the modprobe_path[]
string. This can be used to set it to the empty string initially, thus
effectively disabling request_module() during early boot until userspace
writes a new value via the /proc/sys/kernel/modprobe interface. [1]
When building a custom kernel (often for an embedded target), it's normal
to build everything into the kernel that is needed for booting, and indeed
the initramfs often contains no modules at all, so every such
request_module() done before userspace init has mounted the real rootfs is
a waste of time.
This is particularly useful when combined with the previous patch, which
made the initramfs unpacking asynchronous - for that to work, it had to
make any usermodehelper call wait for the unpacking to finish before
attempting to invoke the userspace helper. By eliminating all such
(known-to-be-futile) calls of usermodehelper, the initramfs unpacking and
the {device,late}_initcalls can proceed in parallel for much longer.
For a relatively slow ppc board I'm working on, the two patches combined
lead to 0.2s faster boot - but more importantly, the fact that the
initramfs unpacking proceeds completely in the background while devices
get probed means I get to handle the gpio watchdog in time without getting
reset.
[1] __request_module() already has an early -ENOENT return when
modprobe_path is the empty string.
Link: https://lkml.kernel.org/r/20210313212528.2956377-3-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Jessica Yu <jeyu@kernel.org>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "background initramfs unpacking, and CONFIG_MODPROBE_PATH", v3.
These two patches are independent, but better-together.
The second is a rather trivial patch that simply allows the developer to
change "/sbin/modprobe" to something else - e.g. the empty string, so
that all request_module() during early boot return -ENOENT early, without
even spawning a usermode helper, needlessly synchronizing with the
initramfs unpacking.
The first patch delegates decompressing the initramfs to a worker thread,
allowing do_initcalls() in main.c to proceed to the device_ and late_
initcalls without waiting for that decompression (and populating of
rootfs) to finish. Obviously, some of those later calls may rely on the
initramfs being available, so I've added synchronization points in the
firmware loader and usermodehelper paths - there might be other places
that would need this, but so far no one has been able to think of any
places I have missed.
There's not much to win if most of the functionality needed during boot is
only available as modules. But systems with a custom-made .config and
initramfs can boot faster, partly due to utilizing more than one cpu
earlier, partly by avoiding known-futile modprobe calls (which would still
trigger synchronization with the initramfs unpacking, thus eliminating
most of the first benefit).
This patch (of 2):
Most of the boot process doesn't actually need anything from the
initramfs, until of course PID1 is to be executed. So instead of doing
the decompressing and populating of the initramfs synchronously in
populate_rootfs() itself, push that off to a worker thread.
This is primarily motivated by an embedded ppc target, where unpacking
even the rather modest sized initramfs takes 0.6 seconds, which is long
enough that the external watchdog becomes unhappy that it doesn't get
attention soon enough. By doing the initramfs decompression in a worker
thread, we get to do the device_initcalls and hence start petting the
watchdog much sooner.
Normal desktops might benefit as well. On my mostly stock Ubuntu kernel,
my initramfs is a 26M xz-compressed blob, decompressing to around 126M.
That takes almost two seconds:
[ 0.201454] Trying to unpack rootfs image as initramfs...
[ 1.976633] Freeing initrd memory: 29416K
Before this patch, these lines occur consecutively in dmesg. With this
patch, the timestamps on these two lines is roughly the same as above, but
with 172 lines inbetween - so more than one cpu has been kept busy doing
work that would otherwise only happen after the populate_rootfs()
finished.
Should one of the initcalls done after rootfs_initcall time (i.e., device_
and late_ initcalls) need something from the initramfs (say, a kernel
module or a firmware blob), it will simply wait for the initramfs
unpacking to be done before proceeding, which should in theory make this
completely safe.
But if some driver pokes around in the filesystem directly and not via one
of the official kernel interfaces (i.e. request_firmware*(),
call_usermodehelper*) that theory may not hold - also, I certainly might
have missed a spot when sprinkling wait_for_initramfs(). So there is an
escape hatch in the form of an initramfs_async= command line parameter.
Link: https://lkml.kernel.org/r/20210313212528.2956377-1-linux@rasmusvillemoes.dk
Link: https://lkml.kernel.org/r/20210313212528.2956377-2-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's currently nigh impossible to get these pr_debug()s to print
something. Being guarded by initcall_debug means one has to enable tons
of other debug output during boot, and the system_state condition further
means it's impossible to get them when loading modules later.
Also, the compiler can't know that these global conditions do not change,
so there are W=2 warnings
kernel/async.c:125:9: warning: `calltime' may be used uninitialized in this function [-Wmaybe-uninitialized]
kernel/async.c:300:9: warning: `starttime' may be used uninitialized in this function [-Wmaybe-uninitialized]
Make it possible, for a DYNAMIC_DEBUG kernel, to get these to print their
messages by booting with appropriate 'dyndbg="file async.c +p"' command
line argument. For a non-DYNAMIC_DEBUG kernel, pr_debug() compiles to
nothing.
This does cost doing an unconditional ktime_get() for the starttime value,
but the corresponding ktime_get for the end time can be elided by
factoring it into a function which only gets called if the printk()
arguments end up being evaluated.
Link: https://lkml.kernel.org/r/20210309151723.1907838-1-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
request_free_mem_region() is used to find an empty range of physical
addresses for hotplugging ZONE_DEVICE memory. It does this by iterating
over the range of possible addresses using region_intersects() to see if
the range is free before calling request_mem_region() to allocate the
region.
However the resource_lock is dropped between these two calls meaning by
the time request_mem_region() is called in request_free_mem_region()
another thread may have already reserved the requested region. This
results in unexpected failures and a message in the kernel log from
hitting this condition:
/*
* mm/hmm.c reserves physical addresses which then
* become unavailable to other users. Conflicts are
* not expected. Warn to aid debugging if encountered.
*/
if (conflict->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY) {
pr_warn("Unaddressable device %s %pR conflicts with %pR",
conflict->name, conflict, res);
These unexpected failures can be corrected by holding resource_lock across
the two calls. This also requires memory allocation to be performed prior
to taking the lock.
Link: https://lkml.kernel.org/r/20210419070109.4780-3-apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Muchun Song <smuchun@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "kernel/resource: make walk_system_ram_res() and walk_mem_res() search the whole tree", v2.
Playing with kdump+virtio-mem I noticed that kexec_file_load() does not
consider System RAM added via dax/kmem and virtio-mem when preparing the
elf header for kdump. Looking into the details, the logic used in
walk_system_ram_res() and walk_mem_res() seems to be outdated.
walk_system_ram_range() already does the right thing, let's change
walk_system_ram_res() and walk_mem_res(), and clean up.
Loading a kdump kernel via "kexec -p -s" ... will result in the kdump
kernel to also dump dax/kmem and virtio-mem added System RAM now.
Note: kexec-tools on x86-64 also have to be updated to consider this
memory in the kexec_load() case when processing /proc/iomem.
This patch (of 3):
It used to be true that we can have system RAM (IORESOURCE_SYSTEM_RAM |
IORESOURCE_BUSY) only on the first level in the resource tree. However,
this is no longer holds for driver-managed system RAM (i.e., added via
dax/kmem and virtio-mem), which gets added on lower levels, for example,
inside device containers.
We have two users of walk_system_ram_res(), which currently only
consideres the first level:
a) kernel/kexec_file.c:kexec_walk_resources() -- We properly skip
IORESOURCE_SYSRAM_DRIVER_MANAGED resources via
locate_mem_hole_callback(), so even after this change, we won't be
placing kexec images onto dax/kmem and virtio-mem added memory. No
change.
b) arch/x86/kernel/crash.c:fill_up_crash_elf_data() -- we're currently
not adding relevant ranges to the crash elf header, resulting in them
not getting dumped via kdump.
This change fixes loading a crashkernel via kexec_file_load() and
including dax/kmem and virtio-mem added System RAM in the crashdump on
x86-64. Note that e.g,, arm64 relies on memblock data and, therefore,
always considers all added System RAM already.
Let's find all IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY resources, making
the function behave like walk_system_ram_range().
Link: https://lkml.kernel.org/r/20210325115326.7826-1-david@redhat.com
Link: https://lkml.kernel.org/r/20210325115326.7826-2-david@redhat.com
Fixes: ebf71552bb ("virtio-mem: Add parent resource for all added "System RAM"")
Fixes: c221c0b030 ("device-dax: "Hotplug" persistent memory for use like normal RAM")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kmsg_dump(KMSG_DUMP_SHUTDOWN) is called before machine_restart(),
machine_halt(), and machine_power_off(). The only one that is missing
is machine_kexec().
The dmesg output that it contains can be used to study the shutdown
performance of both kernel and systemd during kexec reboot.
Here is example of dmesg data collected after kexec:
root@dplat-cp22:~# cat /sys/fs/pstore/dmesg-ramoops-0 | tail
...
[ 70.914592] psci: CPU3 killed (polled 0 ms)
[ 70.915705] CPU4: shutdown
[ 70.916643] psci: CPU4 killed (polled 4 ms)
[ 70.917715] CPU5: shutdown
[ 70.918725] psci: CPU5 killed (polled 0 ms)
[ 70.919704] CPU6: shutdown
[ 70.920726] psci: CPU6 killed (polled 4 ms)
[ 70.921642] CPU7: shutdown
[ 70.922650] psci: CPU7 killed (polled 0 ms)
Link: https://lkml.kernel.org/r/20210319192326.146000-2-pasha.tatashin@soleen.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Cc: James Morris <jmorris@namei.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a special-case when waiting on a pid (via waitpid, waitid, wait4, etc)
to avoid doing an O(n) scan of children and tracees, and instead do an
O(1) lookup. This improves performance when waiting on a pid from a
thread group with many children and/or tracees.
Time to fork and then call waitpid on the child, from a task that already
has N children [1]:
N | Before | After
-----|---------|------
1 | 74 us | 74 us
20 | 72 us | 75 us
100 | 83 us | 77 us
500 | 99 us | 74 us
1000 | 179 us | 75 us
5000 | 804 us | 79 us
8000 | 1268 us | 78 us
[1]: https://lkml.org/lkml/2021/3/12/1567
This can make a substantial performance improvement for applications with
a thread that has many children or tracees and frequently needs to wait on
them. Tools that use ptrace to intercept syscalls for a large number of
processes are likely to fall into this category. In particular this patch
was developed while building a ptrace-based second generation of the
Shadow emulator [2], for which it allows us to avoid quadratic scaling
(without having to use a workaround that introduces a ~40% performance
penalty) [3]. Other examples of tools that fall into this category which
this patch may help include User Mode Linux [4] and DetTrace [5].
[2]: https://shadow.github.io/
[3]: https://github.com/shadow/shadow/issues/1134#issuecomment-798992292
[4]: https://en.wikipedia.org/wiki/User-mode_Linux
[5]: https://github.com/dettrace/dettrace
Link: https://lkml.kernel.org/r/20210314231544.9379-1-jnewsome@torproject.org
Signed-off-by: James Newsome <jnewsome@torproject.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Christian Brauner <christian@brauner.io>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Current users of the rstat code can source root-level statistics from
the native counters of their respective subsystem, allowing them to
forego aggregation at the root level. This optimization is currently
implemented inside the generic rstat code, which doesn't track the root
cgroup and doesn't invoke the subsystem flush callbacks on it.
However, the memory controller cannot do this optimization, because
cgroup1 breaks out memory specifically for the local level, including at
the root level. In preparation for the memory controller switching to
rstat, move the optimization from rstat core to the controllers.
Afterwards, rstat will always track the root cgroup for changes and
invoke the subsystem callbacks on it; and it's up to the subsystem to
special-case and skip aggregation of the root cgroup if it can source
this information through other, cheaper means.
This is the case for the io controller and the cgroup base stats. In
their respective flush callbacks, check whether the parent is the root
cgroup, and if so, skip the unnecessary upward propagation.
The extra cost of tracking the root cgroup is negligible: on stat
changes, we actually remove a branch that checks for the root. The
queueing for a flush touches only per-cpu data, and only the first stat
change since a flush requires a (per-cpu) lock.
Link: https://lkml.kernel.org/r/20210209163304.77088-6-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rstat currently only supports the default hierarchy in cgroup2. In
order to replace memcg's private stats infrastructure - used in both
cgroup1 and cgroup2 - with rstat, the latter needs to support cgroup1.
The initialization and destruction callbacks for regular cgroups are
already in place. Remove the cgroup_on_dfl() guards to handle cgroup1.
The initialization of the root cgroup is currently hardcoded to only
handle cgrp_dfl_root.cgrp. Move those callbacks to cgroup_setup_root()
and cgroup_destroy_root() to handle the default root as well as the
various cgroup1 roots we may set up during mounting.
The linking of css to cgroups happens in code shared between cgroup1 and
cgroup2 as well. Simply remove the cgroup_on_dfl() guard.
Linkage of the root css to the root cgroup is a bit trickier: per
default, the root css of a subsystem controller belongs to the default
hierarchy (i.e. the cgroup2 root). When a controller is mounted in its
cgroup1 version, the root css is stolen and moved to the cgroup1 root;
on unmount, the css moves back to the default hierarchy. Annotate
rebind_subsystems() to move the root css linkage along between roots.
Link: https://lkml.kernel.org/r/20210209163304.77088-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For simplification commit 991e767385 ("mm: memcontrol: account kernel
stack per node") changed the per zone vmalloc backed stack pages
accounting to per node.
By doing that we have lost a certain precision because those pages might
live in different NUMA nodes. In the end NR_KERNEL_STACK_KB exported to
the userspace might be over estimated on some nodes while underestimated
on others. But this is not a real world problem, just a problem found
by reading the code. So there is no actual data to showing how much
impact it has on users.
This doesn't impose any real problem to correctnes of the kernel
behavior as the counter is not used for any internal processing but it
can cause some confusion to the userspace.
Address the problem by accounting each vmalloc backing page to its own
node.
Link: https://lkml.kernel.org/r/20210303151843.81156-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit d6ad3e286d ("softlockup: Add sched_clock_tick() to avoid kernel
warning on kgdb resume") introduced touch_softlockup_watchdog_sync().
It solved a problem when the watchdog was touched in an atomic context,
the timer callback was proceed right after releasing interrupts, and the
local clock has not been updated yet. In this case, sched_clock_tick()
was called in watchdog_timer_fn() before updating the timer.
So far so good.
Later commit 5d1c0f4a80 ("watchdog: add check for suspended vm in
softlockup detector") added two kvm_check_and_clear_guest_paused()
calls. They touch the watchdog when the guest has been sleeping.
The code makes my head spin around.
Scenario 1:
+ guest did sleep:
+ PVCLOCK_GUEST_STOPPED is set
+ 1st watchdog_timer_fn() invocation:
+ the watchdog is not touched yet
+ is_softlockup() returns too big delay
+ kvm_check_and_clear_guest_paused():
+ clear PVCLOCK_GUEST_STOPPED
+ call touch_softlockup_watchdog_sync()
+ set SOFTLOCKUP_DELAY_REPORT
+ set softlockup_touch_sync
+ return from the timer callback
+ 2nd watchdog_timer_fn() invocation:
+ call sched_clock_tick() even though it is not needed.
The timer callback was invoked again only because the clock
has already been updated in the meantime.
+ call kvm_check_and_clear_guest_paused() that does nothing
because PVCLOCK_GUEST_STOPPED has been cleared already.
+ call update_report_ts() and return. This is fine. Except
that sched_clock_tick() might allow to set it already
during the 1st invocation.
Scenario 2:
+ guest did sleep
+ 1st watchdog_timer_fn() invocation
+ same as in 1st scenario
+ guest did sleep again:
+ set PVCLOCK_GUEST_STOPPED again
+ 2nd watchdog_timer_fn() invocation
+ SOFTLOCKUP_DELAY_REPORT is set from 1st invocation
+ call sched_clock_tick()
+ call kvm_check_and_clear_guest_paused()
+ clear PVCLOCK_GUEST_STOPPED
+ call touch_softlockup_watchdog_sync()
+ set SOFTLOCKUP_DELAY_REPORT
+ set softlockup_touch_sync
+ call update_report_ts() (set real timestamp immediately)
+ return from the timer callback
+ 3rd watchdog_timer_fn() invocation
+ timestamp is set from 2nd invocation
+ softlockup_touch_sync is set but not checked because
the real timestamp is already set
Make the code more straightforward:
1. Always call kvm_check_and_clear_guest_paused() at the very
beginning to handle PVCLOCK_GUEST_STOPPED. It touches the watchdog
when the quest did sleep.
2. Handle the situation when the watchdog has been touched
(SOFTLOCKUP_DELAY_REPORT is set).
Call sched_clock_tick() when touch_*sync() variant was used. It makes
sure that the timestamp will be up to date even when it has been
touched in atomic context or quest did sleep.
As a result, kvm_check_and_clear_guest_paused() is called on a single
location. And the right timestamp is always set when returning from the
timer callback.
Link: https://lkml.kernel.org/r/20210311122130.6788-7-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The softlockup detector does some gymnastic with the variable
soft_watchdog_warn. It was added by the commit 58687acba5
("lockup_detector: Combine nmi_watchdog and softlockup detector").
The purpose is not completely clear. There are the following clues. They
describe the situation how it looked after the above mentioned commit:
1. The variable was checked with a comment "only warn once".
2. The variable was set when softlockup was reported. It was cleared
only when the CPU was not longer in the softlockup state.
3. watchdog_touch_ts was not explicitly updated when the softlockup
was reported. Without this variable, the report would normally
be printed again during every following watchdog_timer_fn()
invocation.
The logic has got even more tangled up by the commit ed235875e2
("kernel/watchdog.c: print traces for all cpus on lockup detection").
After this commit, soft_watchdog_warn is set only when
softlockup_all_cpu_backtrace is enabled. But multiple reports from all
CPUs are prevented by a new variable soft_lockup_nmi_warn.
Conclusion:
The variable probably never worked as intended. In each case, it has not
worked last many years because the softlockup was reported repeatedly
after the full period defined by watchdog_thresh.
The reason is that watchdog gets touched in many known slow paths, for
example, in printk_stack_address(). This code is called also when
printing the softlockup report. It means that the watchdog timestamp gets
updated after each report.
Solution:
Simply remove the logic. People want the periodic report anyway.
Link: https://lkml.kernel.org/r/20210311122130.6788-5-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The softlockup detector currently shows the time spent since the last
report. As a result it is not clear whether a CPU is infinitely hogged by
a single task or if it is a repeated event.
The situation can be simulated with a simply busy loop:
while (true)
cpu_relax();
The softlockup detector produces:
[ 168.277520] watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [cat:4865]
[ 196.277604] watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [cat:4865]
[ 236.277522] watchdog: BUG: soft lockup - CPU#1 stuck for 23s! [cat:4865]
But it should be, something like:
[ 480.372418] watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [cat:4943]
[ 508.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 52s! [cat:4943]
[ 548.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 89s! [cat:4943]
[ 576.372351] watchdog: BUG: soft lockup - CPU#2 stuck for 115s! [cat:4943]
For the better output, add an additional timestamp of the last report.
Only this timestamp is reset when the watchdog is intentionally touched
from slow code paths or when printing the report.
Link: https://lkml.kernel.org/r/20210311122130.6788-4-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The softlockup situation might stay for a long time or even forever. When
it happens, the softlockup debug messages are printed in regular intervals
defined by get_softlockup_thresh().
There is a mystery. The repeated message is printed after the full
interval that is defined by get_softlockup_thresh(). But the timer
callback is called more often as defined by sample_period. The code looks
like the soflockup should get reported in every sample_period when it was
once behind the thresh.
It works only by chance. The watchdog is touched when printing the stall
report, for example, in printk_stack_address().
Make the behavior clear and predictable by explicitly updating the
timestamp in watchdog_timer_fn() when the report gets printed.
Link: https://lkml.kernel.org/r/20210311122130.6788-3-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "watchdog/softlockup: Report overall time and some cleanup", v2.
I dug deep into the softlockup watchdog history when time permitted this
year. And reworked the patchset that fixed timestamps and cleaned up the
code[2].
I split it into very small steps and did even more code clean up. The
result looks quite strightforward and I am pretty confident with the
changes.
[1] v2: https://lore.kernel.org/r/20201210160038.31441-1-pmladek@suse.com
[2] v1: https://lore.kernel.org/r/20191024114928.15377-1-pmladek@suse.com
This patch (of 6):
There are many touch_*watchdog() functions. They are called in situations
where the watchdog could report false positives or create unnecessary
noise. For example, when CPU is entering idle mode, a virtual machine is
stopped, or a lot of messages are printed in the atomic context.
These functions set SOFTLOCKUP_RESET instead of a real timestamp. It
allows to call them even in a context where jiffies might be outdated.
For example, in an atomic context.
The real timestamp is set by __touch_watchdog() that is called from the
watchdog timer callback.
Rename this callback to update_touch_ts(). It better describes the effect
and clearly distinguish is from the other touch_*watchdog() functions.
Another motivation is that two timestamps are going to be used. One will
be used for the total softlockup time. The other will be used to measure
time since the last report. The new function name will help to
distinguish which timestamp is being updated.
Link: https://lkml.kernel.org/r/20210311122130.6788-1-pmladek@suse.com
Link: https://lkml.kernel.org/r/20210311122130.6788-2-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull Kconfig updates from Masahiro Yamada:
- Change 'option defconfig' to the environment variable
KCONFIG_DEFCONFIG_LIST
- Refactor tinyconfig without using allnoconfig_y
- Remove 'option allnoconfig_y' syntax
- Change 'option modules' to 'modules'
- Do not use /boot/config-* etc. as base config for cross-compilation
- Fix a search bug in nconf
- Various code cleanups
* tag 'kconfig-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
kconfig: refactor .gitignore
kconfig: highlight xconfig 'comment' lines with '***'
kconfig: highlight gconfig 'comment' lines with '***'
kconfig: gconf: remove unused code
kconfig: remove unused PACKAGE definition
kconfig: nconf: stop endless search loops
kconfig: split menu.c out of parser.y
kconfig: nconf: refactor in print_in_middle()
kconfig: nconf: remove meaningless wattrset() call from show_menu()
kconfig: nconf: change set_config_filename() to void function
kconfig: nconf: refactor attributes setup code
kconfig: nconf: remove unneeded default for menu prompt
kconfig: nconf: get rid of (void) casts from wattrset() calls
kconfig: nconf: fix NORMAL attributes
kconfig: mconf,nconf: remove unneeded '\0' termination after snprintf()
kconfig: use /boot/config-* etc. as DEFCONFIG_LIST only for native build
kconfig: change sym_change_count to a boolean flag
kconfig: nconf: fix core dump when searching in empty menu
kconfig: lxdialog: A spello fix and a punctuation added
kconfig: streamline_config.pl: Couple of typo fixes
...
Pull Kbuild updates from Masahiro Yamada:
- Evaluate $(call cc-option,...) etc. only for build targets
- Add CONFIG_VMLINUX_MAP to generate .map file when linking vmlinux
- Remove unnecessary --gcc-toolchains Clang flag because the --prefix
flag finds the toolchains
- Do not pass Clang's --prefix flag when using the integrated as
- Check the assembler version in Kconfig time
- Add new CONFIG options, AS_VERSION, AS_IS_GNU, AS_IS_LLVM to clean up
some dependencies in Kconfig
- Fix invalid Module.symvers creation when building only modules
without vmlinux
- Fix false-positive modpost warnings when CONFIG_TRIM_UNUSED_KSYMS is
set, but there is no module to build
- Refactor module installation Makefile
- Support zstd for module compression
- Convert alpha and ia64 to use generic shell scripts to generate the
syscall headers
- Add a new elfnote to indicate if the kernel was built with LTO, which
will be used by pahole
- Flatten the directory structure under include/config/ so CONFIG
options and filenames match
- Change the deb source package name from linux-$(KERNELRELEASE) to
linux-upstream
* tag 'kbuild-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (42 commits)
kbuild: Add $(KBUILD_HOSTLDFLAGS) to 'has_libelf' test
kbuild: deb-pkg: change the source package name to linux-upstream
tools: do not include scripts/Kbuild.include
kbuild: redo fake deps at include/config/*.h
kbuild: remove TMPO from try-run
MAINTAINERS: add pattern for dummy-tools
kbuild: add an elfnote for whether vmlinux is built with lto
ia64: syscalls: switch to generic syscallhdr.sh
ia64: syscalls: switch to generic syscalltbl.sh
alpha: syscalls: switch to generic syscallhdr.sh
alpha: syscalls: switch to generic syscalltbl.sh
sysctl: use min() helper for namecmp()
kbuild: add support for zstd compressed modules
kbuild: remove CONFIG_MODULE_COMPRESS
kbuild: merge scripts/Makefile.modsign to scripts/Makefile.modinst
kbuild: move module strip/compression code into scripts/Makefile.modinst
kbuild: refactor scripts/Makefile.modinst
kbuild: rename extmod-prefix to extmod_prefix
kbuild: check module name conflict for external modules as well
kbuild: show the target directory for depmod log
...
Pull networking updates from Jakub Kicinski:
"Core:
- bpf:
- allow bpf programs calling kernel functions (initially to
reuse TCP congestion control implementations)
- enable task local storage for tracing programs - remove the
need to store per-task state in hash maps, and allow tracing
programs access to task local storage previously added for
BPF_LSM
- add bpf_for_each_map_elem() helper, allowing programs to walk
all map elements in a more robust and easier to verify fashion
- sockmap: support UDP and cross-protocol BPF_SK_SKB_VERDICT
redirection
- lpm: add support for batched ops in LPM trie
- add BTF_KIND_FLOAT support - mostly to allow use of BTF on
s390 which has floats in its headers files
- improve BPF syscall documentation and extend the use of kdoc
parsing scripts we already employ for bpf-helpers
- libbpf, bpftool: support static linking of BPF ELF files
- improve support for encapsulation of L2 packets
- xdp: restructure redirect actions to avoid a runtime lookup,
improving performance by 4-8% in microbenchmarks
- xsk: build skb by page (aka generic zerocopy xmit) - improve
performance of software AF_XDP path by 33% for devices which don't
need headers in the linear skb part (e.g. virtio)
- nexthop: resilient next-hop groups - improve path stability on
next-hops group changes (incl. offload for mlxsw)
- ipv6: segment routing: add support for IPv4 decapsulation
- icmp: add support for RFC 8335 extended PROBE messages
- inet: use bigger hash table for IP ID generation
- tcp: deal better with delayed TX completions - make sure we don't
give up on fast TCP retransmissions only because driver is slow in
reporting that it completed transmitting the original
- tcp: reorder tcp_congestion_ops for better cache locality
- mptcp:
- add sockopt support for common TCP options
- add support for common TCP msg flags
- include multiple address ids in RM_ADDR
- add reset option support for resetting one subflow
- udp: GRO L4 improvements - improve 'forward' / 'frag_list'
co-existence with UDP tunnel GRO, allowing the first to take place
correctly even for encapsulated UDP traffic
- micro-optimize dev_gro_receive() and flow dissection, avoid
retpoline overhead on VLAN and TEB GRO
- use less memory for sysctls, add a new sysctl type, to allow using
u8 instead of "int" and "long" and shrink networking sysctls
- veth: allow GRO without XDP - this allows aggregating UDP packets
before handing them off to routing, bridge, OvS, etc.
- allow specifing ifindex when device is moved to another namespace
- netfilter:
- nft_socket: add support for cgroupsv2
- nftables: add catch-all set element - special element used to
define a default action in case normal lookup missed
- use net_generic infra in many modules to avoid allocating
per-ns memory unnecessarily
- xps: improve the xps handling to avoid potential out-of-bound
accesses and use-after-free when XPS change race with other
re-configuration under traffic
- add a config knob to turn off per-cpu netdev refcnt to catch
underflows in testing
Device APIs:
- add WWAN subsystem to organize the WWAN interfaces better and
hopefully start driving towards more unified and vendor-
independent APIs
- ethtool:
- add interface for reading IEEE MIB stats (incl. mlx5 and bnxt
support)
- allow network drivers to dump arbitrary SFP EEPROM data,
current offset+length API was a poor fit for modern SFP which
define EEPROM in terms of pages (incl. mlx5 support)
- act_police, flow_offload: add support for packet-per-second
policing (incl. offload for nfp)
- psample: add additional metadata attributes like transit delay for
packets sampled from switch HW (and corresponding egress and
policy-based sampling in the mlxsw driver)
- dsa: improve support for sandwiched LAGs with bridge and DSA
- netfilter:
- flowtable: use direct xmit in topologies with IP forwarding,
bridging, vlans etc.
- nftables: counter hardware offload support
- Bluetooth:
- improvements for firmware download w/ Intel devices
- add support for reading AOSP vendor capabilities
- add support for virtio transport driver
- mac80211:
- allow concurrent monitor iface and ethernet rx decap
- set priority and queue mapping for injected frames
- phy: add support for Clause-45 PHY Loopback
- pci/iov: add sysfs MSI-X vector assignment interface to distribute
MSI-X resources to VFs (incl. mlx5 support)
New hardware/drivers:
- dsa: mv88e6xxx: add support for Marvell mv88e6393x - 11-port
Ethernet switch with 8x 1-Gigabit Ethernet and 3x 10-Gigabit
interfaces.
- dsa: support for legacy Broadcom tags used on BCM5325, BCM5365 and
BCM63xx switches
- Microchip KSZ8863 and KSZ8873; 3x 10/100Mbps Ethernet switches
- ath11k: support for QCN9074 a 802.11ax device
- Bluetooth: Broadcom BCM4330 and BMC4334
- phy: Marvell 88X2222 transceiver support
- mdio: add BCM6368 MDIO mux bus controller
- r8152: support RTL8153 and RTL8156 (USB Ethernet) chips
- mana: driver for Microsoft Azure Network Adapter (MANA)
- Actions Semi Owl Ethernet MAC
- can: driver for ETAS ES58X CAN/USB interfaces
Pure driver changes:
- add XDP support to: enetc, igc, stmmac
- add AF_XDP support to: stmmac
- virtio:
- page_to_skb() use build_skb when there's sufficient tailroom
(21% improvement for 1000B UDP frames)
- support XDP even without dedicated Tx queues - share the Tx
queues with the stack when necessary
- mlx5:
- flow rules: add support for mirroring with conntrack, matching
on ICMP, GTP, flex filters and more
- support packet sampling with flow offloads
- persist uplink representor netdev across eswitch mode changes
- allow coexistence of CQE compression and HW time-stamping
- add ethtool extended link error state reporting
- ice, iavf: support flow filters, UDP Segmentation Offload
- dpaa2-switch:
- move the driver out of staging
- add spanning tree (STP) support
- add rx copybreak support
- add tc flower hardware offload on ingress traffic
- ionic:
- implement Rx page reuse
- support HW PTP time-stamping
- octeon: support TC hardware offloads - flower matching on ingress
and egress ratelimitting.
- stmmac:
- add RX frame steering based on VLAN priority in tc flower
- support frame preemption (FPE)
- intel: add cross time-stamping freq difference adjustment
- ocelot:
- support forwarding of MRP frames in HW
- support multiple bridges
- support PTP Sync one-step timestamping
- dsa: mv88e6xxx, dpaa2-switch: offload bridge port flags like
learning, flooding etc.
- ipa: add IPA v4.5, v4.9 and v4.11 support (Qualcomm SDX55, SM8350,
SC7280 SoCs)
- mt7601u: enable TDLS support
- mt76:
- add support for 802.3 rx frames (mt7915/mt7615)
- mt7915 flash pre-calibration support
- mt7921/mt7663 runtime power management fixes"
* tag 'net-next-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2451 commits)
net: selftest: fix build issue if INET is disabled
net: netrom: nr_in: Remove redundant assignment to ns
net: tun: Remove redundant assignment to ret
net: phy: marvell: add downshift support for M88E1240
net: dsa: ksz: Make reg_mib_cnt a u8 as it never exceeds 255
net/sched: act_ct: Remove redundant ct get and check
icmp: standardize naming of RFC 8335 PROBE constants
bpf, selftests: Update array map tests for per-cpu batched ops
bpf: Add batched ops support for percpu array
bpf: Implement formatted output helpers with bstr_printf
seq_file: Add a seq_bprintf function
sfc: adjust efx->xdp_tx_queue_count with the real number of initialized queues
net:nfc:digital: Fix a double free in digital_tg_recv_dep_req
net: fix a concurrency bug in l2tp_tunnel_register()
net/smc: Remove redundant assignment to rc
mpls: Remove redundant assignment to err
llc2: Remove redundant assignment to rc
net/tls: Remove redundant initialization of record
rds: Remove redundant assignment to nr_sig
dt-bindings: net: mdio-gpio: add compatible for microchip,mdio-smi0
...
Pull x86 tlb updates from Ingo Molnar:
"The x86 MM changes in this cycle were:
- Implement concurrent TLB flushes, which overlaps the local TLB
flush with the remote TLB flush.
In testing this improved sysbench performance measurably by a
couple of percentage points, especially if TLB-heavy security
mitigations are active.
- Further micro-optimizations to improve the performance of TLB
flushes"
* tag 'x86-mm-2021-04-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
smp: Micro-optimize smp_call_function_many_cond()
smp: Inline on_each_cpu_cond() and on_each_cpu()
x86/mm/tlb: Remove unnecessary uses of the inline keyword
cpumask: Mark functions as pure
x86/mm/tlb: Do not make is_lazy dirty for no reason
x86/mm/tlb: Privatize cpu_tlbstate
x86/mm/tlb: Flush remote and local TLBs concurrently
x86/mm/tlb: Open-code on_each_cpu_cond_mask() for tlb_is_not_lazy()
x86/mm/tlb: Unify flush_tlb_func_local() and flush_tlb_func_remote()
smp: Run functions concurrently in smp_call_function_many_cond()
Pull fsnotify updates from Jan Kara:
- support for limited fanotify functionality for unpriviledged users
- faster merging of fanotify events
- a few smaller fsnotify improvements
* tag 'fsnotify_for_v5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
shmem: allow reporting fanotify events with file handles on tmpfs
fs: introduce a wrapper uuid_to_fsid()
fanotify_user: use upper_32_bits() to verify mask
fanotify: support limited functionality for unprivileged users
fanotify: configurable limits via sysfs
fanotify: limit number of event merge attempts
fsnotify: use hash table for faster events merge
fanotify: mix event info and pid into merge key hash
fanotify: reduce event objectid to 29-bit hash
fsnotify: allow fsnotify_{peek,remove}_first_event with empty queue
Pull quota, ext2, reiserfs updates from Jan Kara:
- support for path (instead of device) based quotactl syscall
(quotactl_path(2))
- ext2 conversion to kmap_local()
- other minor cleanups & fixes
* tag 'for_v5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
fs/reiserfs/journal.c: delete useless variables
fs/ext2: Replace kmap() with kmap_local_page()
ext2: Match up ext2_put_page() with ext2_dotdot() and ext2_find_entry()
fs/ext2/: fix misspellings using codespell tool
quota: report warning limits for realtime space quotas
quota: wire up quotactl_path
quota: Add mountpath based quota support
Pull io_uring updates from Jens Axboe:
- Support for multi-shot mode for POLL requests
- More efficient reference counting. This is shamelessly stolen from
the mm side. Even though referencing is mostly single/dual user, the
128 count was retained to keep the code the same. Maybe this
should/could be made generic at some point.
- Removal of the need to have a manager thread for each ring. The
manager threads only job was checking and creating new io-threads as
needed, instead we handle this from the queue path.
- Allow SQPOLL without CAP_SYS_ADMIN or CAP_SYS_NICE. Since 5.12, this
thread is "just" a regular application thread, so no need to restrict
use of it anymore.
- Cleanup of how internal async poll data lifetime is managed.
- Fix for syzbot reported crash on SQPOLL cancelation.
- Make buffer registration more like file registrations, which includes
flexibility in avoiding full set unregistration and re-registration.
- Fix for io-wq affinity setting.
- Be a bit more defensive in task->pf_io_worker setup.
- Various SQPOLL fixes.
- Cleanup of SQPOLL creds handling.
- Improvements to in-flight request tracking.
- File registration cleanups.
- Tons of cleanups and little fixes
* tag 'for-5.13/io_uring-2021-04-27' of git://git.kernel.dk/linux-block: (156 commits)
io_uring: maintain drain logic for multishot poll requests
io_uring: Check current->io_uring in io_uring_cancel_sqpoll
io_uring: fix NULL reg-buffer
io_uring: simplify SQPOLL cancellations
io_uring: fix work_exit sqpoll cancellations
io_uring: Fix uninitialized variable up.resv
io_uring: fix invalid error check after malloc
io_uring: io_sq_thread() no longer needs to reset current->pf_io_worker
kernel: always initialize task->pf_io_worker to NULL
io_uring: update sq_thread_idle after ctx deleted
io_uring: add full-fledged dynamic buffers support
io_uring: implement fixed buffers registration similar to fixed files
io_uring: prepare fixed rw for dynanic buffers
io_uring: keep table of pointers to ubufs
io_uring: add generic rsrc update with tags
io_uring: add IORING_REGISTER_RSRC
io_uring: enumerate dynamic resources
io_uring: add generic path for rsrc update
io_uring: preparation for rsrc tagging
io_uring: decouple CQE filling from requests
...
Pull scheduler updates from Ingo Molnar:
- Clean up SCHED_DEBUG: move the decades old mess of sysctl, procfs and
debugfs interfaces to a unified debugfs interface.
- Signals: Allow caching one sigqueue object per task, to improve
performance & latencies.
- Improve newidle_balance() irq-off latencies on systems with a large
number of CPU cgroups.
- Improve energy-aware scheduling
- Improve the PELT metrics for certain workloads
- Reintroduce select_idle_smt() to improve load-balancing locality -
but without the previous regressions
- Add 'scheduler latency debugging': warn after long periods of pending
need_resched. This is an opt-in feature that requires the enabling of
the LATENCY_WARN scheduler feature, or the use of the
resched_latency_warn_ms=xx boot parameter.
- CPU hotplug fixes for HP-rollback, and for the 'fail' interface. Fix
remaining balance_push() vs. hotplug holes/races
- PSI fixes, plus allow /proc/pressure/ files to be written by
CAP_SYS_RESOURCE tasks as well
- Fix/improve various load-balancing corner cases vs. capacity margins
- Fix sched topology on systems with NUMA diameter of 3 or above
- Fix PF_KTHREAD vs to_kthread() race
- Minor rseq optimizations
- Misc cleanups, optimizations, fixes and smaller updates
* tag 'sched-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (61 commits)
cpumask/hotplug: Fix cpu_dying() state tracking
kthread: Fix PF_KTHREAD vs to_kthread() race
sched/debug: Fix cgroup_path[] serialization
sched,psi: Handle potential task count underflow bugs more gracefully
sched: Warn on long periods of pending need_resched
sched/fair: Move update_nohz_stats() to the CONFIG_NO_HZ_COMMON block to simplify the code & fix an unused function warning
sched/debug: Rename the sched_debug parameter to sched_verbose
sched,fair: Alternative sched_slice()
sched: Move /proc/sched_debug to debugfs
sched,debug: Convert sysctl sched_domains to debugfs
debugfs: Implement debugfs_create_str()
sched,preempt: Move preempt_dynamic to debug.c
sched: Move SCHED_DEBUG sysctl to debugfs
sched: Don't make LATENCYTOP select SCHED_DEBUG
sched: Remove sched_schedstats sysctl out from under SCHED_DEBUG
sched/numa: Allow runtime enabling/disabling of NUMA balance without SCHED_DEBUG
sched: Use cpu_dying() to fix balance_push vs hotplug-rollback
cpumask: Introduce DYING mask
cpumask: Make cpu_{online,possible,present,active}() inline
rseq: Optimise rseq_get_rseq_cs() and clear_rseq_cs()
...
Pull perf event updates from Ingo Molnar:
- Improve Intel uncore PMU support:
- Parse uncore 'discovery tables' - a new hardware capability
enumeration method introduced on the latest Intel platforms. This
table is in a well-defined PCI namespace location and is read via
MMIO. It is organized in an rbtree.
These uncore tables will allow the discovery of standard counter
blocks, but fancier counters still need to be enumerated
explicitly.
- Add Alder Lake support
- Improve IIO stacks to PMON mapping support on Skylake servers
- Add Intel Alder Lake PMU support - which requires the introduction of
'hybrid' CPUs and PMUs. Alder Lake is a mix of Golden Cove ('big')
and Gracemont ('small' - Atom derived) cores.
The CPU-side feature set is entirely symmetrical - but on the PMU
side there's core type dependent PMU functionality.
- Reduce data loss with CPU level hardware tracing on Intel PT / AUX
profiling, by fixing the AUX allocation watermark logic.
- Improve ring buffer allocation on NUMA systems
- Put 'struct perf_event' into their separate kmem_cache pool
- Add support for synchronous signals for select perf events. The
immediate motivation is to support low-overhead sampling-based race
detection for user-space code. The feature consists of the following
main changes:
- Add thread-only event inheritance via
perf_event_attr::inherit_thread, which limits inheritance of
events to CLONE_THREAD.
- Add the ability for events to not leak through exec(), via
perf_event_attr::remove_on_exec.
- Allow the generation of SIGTRAP via perf_event_attr::sigtrap,
extend siginfo with an u64 ::si_perf, and add the breakpoint
information to ::si_addr and ::si_perf if the event is
PERF_TYPE_BREAKPOINT.
The siginfo support is adequate for breakpoints right now - but the
new field can be used to introduce support for other types of
metadata passed over siginfo as well.
- Misc fixes, cleanups and smaller updates.
* tag 'perf-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits)
signal, perf: Add missing TRAP_PERF case in siginfo_layout()
signal, perf: Fix siginfo_t by avoiding u64 on 32-bit architectures
perf/x86: Allow for 8<num_fixed_counters<16
perf/x86/rapl: Add support for Intel Alder Lake
perf/x86/cstate: Add Alder Lake CPU support
perf/x86/msr: Add Alder Lake CPU support
perf/x86/intel/uncore: Add Alder Lake support
perf: Extend PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE
perf/x86/intel: Add Alder Lake Hybrid support
perf/x86: Support filter_match callback
perf/x86/intel: Add attr_update for Hybrid PMUs
perf/x86: Add structures for the attributes of Hybrid PMUs
perf/x86: Register hybrid PMUs
perf/x86: Factor out x86_pmu_show_pmu_cap
perf/x86: Remove temporary pmu assignment in event_init
perf/x86/intel: Factor out intel_pmu_check_extra_regs
perf/x86/intel: Factor out intel_pmu_check_event_constraints
perf/x86/intel: Factor out intel_pmu_check_num_counters
perf/x86: Hybrid PMU support for extra_regs
perf/x86: Hybrid PMU support for event constraints
...
Pull locking updates from Ingo Molnar:
- rtmutex cleanup & spring cleaning pass that removes ~400 lines of
code
- Futex simplifications & cleanups
- Add debugging to the CSD code, to help track down a tenacious race
(or hw problem)
- Add lockdep_assert_not_held(), to allow code to require a lock to not
be held, and propagate this into the ath10k driver
- Misc LKMM documentation updates
- Misc KCSAN updates: cleanups & documentation updates
- Misc fixes and cleanups
- Fix locktorture bugs with ww_mutexes
* tag 'locking-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits)
kcsan: Fix printk format string
static_call: Relax static_call_update() function argument type
static_call: Fix unused variable warn w/o MODULE
locking/rtmutex: Clean up signal handling in __rt_mutex_slowlock()
locking/rtmutex: Restrict the trylock WARN_ON() to debug
locking/rtmutex: Fix misleading comment in rt_mutex_postunlock()
locking/rtmutex: Consolidate the fast/slowpath invocation
locking/rtmutex: Make text section and inlining consistent
locking/rtmutex: Move debug functions as inlines into common header
locking/rtmutex: Decrapify __rt_mutex_init()
locking/rtmutex: Remove pointless CONFIG_RT_MUTEXES=n stubs
locking/rtmutex: Inline chainwalk depth check
locking/rtmutex: Move rt_mutex_debug_task_free() to rtmutex.c
locking/rtmutex: Remove empty and unused debug stubs
locking/rtmutex: Consolidate rt_mutex_init()
locking/rtmutex: Remove output from deadlock detector
locking/rtmutex: Remove rtmutex deadlock tester leftovers
locking/rtmutex: Remove rt_mutex_timed_lock()
MAINTAINERS: Add myself as futex reviewer
locking/mutex: Remove repeated declaration
...
