Pull perf and timer fixes from Ingo Molnar:
"A fix for a posix CPU timers bug, and a perf printk message fix"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86: Fix bogus kernel printk, again
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
posix_cpu_timer: Exit early when process has been reaped
Xiaolong Ye reported lock debug warnings triggered by the following commit:
8de4a0066106 ("perf/x86: Convert the core to the hotplug state machine")
The bug is the following: the cpuhp_bp_states[] array is cut short when
CONFIG_SMP=n, but the dynamically registered callbacks are stored nevertheless
and happily scribble outside of the array bounds...
We need to store them in case that the state is unregistered so we can invoke
the teardown function. That's independent of CONFIG_SMP. Make sure the array
is large enough.
Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Adam Borowski <kilobyte@angband.pl>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: lkp@01.org
Cc: stable@vger.kernel.org
Cc: tipbuild@zytor.com
Fixes: cff7d378d3 "cpu/hotplug: Convert to a state machine for the control processor"
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1607122144560.4083@nanos
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Variable "now" seems to be genuinely used unintialized
if branch
if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
is not taken and branch
if (unlikely(sighand == NULL)) {
is taken. In this case the process has been reaped and the timer is marked as
disarmed anyway. So none of the postprocessing of the sample is
required. Return right away.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20160707223911.GA26483@p183.telecom.by
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The following commit:
66eb579e66 ("perf: allow for PMU-specific event filtering")
added the pmu::filter_match() callback. This was intended to
avoid HW constraints on events from resulting in extremely
pessimistic scheduling.
However, pmu::filter_match() is only called for the leader of each event
group. When the leader is a SW event, we do not filter the groups, and
may fail at pmu::add() time, and when this happens we'll give up on
scheduling any event groups later in the list until they are rotated
ahead of the failing group.
This can result in extremely sub-optimal event scheduling behaviour,
e.g. if running the following on a big.LITTLE platform:
$ taskset -c 0 ./perf stat \
-e 'a57{context-switches,armv8_cortex_a57/config=0x11/}' \
-e 'a53{context-switches,armv8_cortex_a53/config=0x11/}' \
ls
<not counted> context-switches (0.00%)
<not counted> armv8_cortex_a57/config=0x11/ (0.00%)
24 context-switches (37.36%)
57589154 armv8_cortex_a53/config=0x11/ (37.36%)
Here the 'a53' event group was always eligible to be scheduled, but
the 'a57' group never eligible to be scheduled, as the task was always
affine to a Cortex-A53 CPU. The SW (group leader) event in the 'a57'
group was eligible, but the HW event failed at pmu::add() time,
resulting in ctx_flexible_sched_in giving up on scheduling further
groups with HW events.
One way of avoiding this is to check pmu::filter_match() on siblings
as well as the group leader. If any of these fail their
pmu::filter_match() call, we must skip the entire group before
attempting to add any events.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
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: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Fixes: 66eb579e66 ("perf: allow for PMU-specific event filtering")
Link: http://lkml.kernel.org/r/1465917041-15339-1-git-send-email-mark.rutland@arm.com
[ Small readability edits. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull audit fixes from Paul Moore:
"Two small patches to fix audit problems in 4.7-rcX: the first fixes a
potential kref leak, the second removes some header file noise.
The first is an important bug fix that really should go in before 4.7
is released, the second is not critical, but falls into the very-nice-
to-have category so I'm including in the pull request.
Both patches are straightforward, self-contained, and pass our
testsuite without problem"
* 'stable-4.7' of git://git.infradead.org/users/pcmoore/audit:
audit: move audit_get_tty to reduce scope and kabi changes
audit: move calcs after alloc and check when logging set loginuid
Pull networking fixes from David Miller:
"I've been traveling so this accumulates more than week or so of bug
fixing. It perhaps looks a little worse than it really is.
1) Fix deadlock in ath10k driver, from Ben Greear.
2) Increase scan timeout in iwlwifi, from Luca Coelho.
3) Unbreak STP by properly reinjecting STP packets back into the
stack. Regression fix from Ido Schimmel.
4) Mediatek driver fixes (missing malloc failure checks, leaking of
scratch memory, wrong indexing when mapping TX buffers, etc.) from
John Crispin.
5) Fix endianness bug in icmpv6_err() handler, from Hannes Frederic
Sowa.
6) Fix hashing of flows in UDP in the ruseport case, from Xuemin Su.
7) Fix netlink notifications in ovs for tunnels, delete link messages
are never emitted because of how the device registry state is
handled. From Nicolas Dichtel.
8) Conntrack module leaks kmemcache on unload, from Florian Westphal.
9) Prevent endless jump loops in nft rules, from Liping Zhang and
Pablo Neira Ayuso.
10) Not early enough spinlock initialization in mlx4, from Eric
Dumazet.
11) Bind refcount leak in act_ipt, from Cong WANG.
12) Missing RCU locking in HTB scheduler, from Florian Westphal.
13) Several small MACSEC bug fixes from Sabrina Dubroca (missing RCU
barrier, using heap for SG and IV, and erroneous use of async flag
when allocating AEAD conext.)
14) RCU handling fix in TIPC, from Ying Xue.
15) Pass correct protocol down into ipv4_{update_pmtu,redirect}() in
SIT driver, from Simon Horman.
16) Socket timer deadlock fix in TIPC from Jon Paul Maloy.
17) Fix potential deadlock in team enslave, from Ido Schimmel.
18) Memory leak in KCM procfs handling, from Jiri Slaby.
19) ESN generation fix in ipv4 ESP, from Herbert Xu.
20) Fix GFP_KERNEL allocations with locks held in act_ife, from Cong
WANG.
21) Use after free in netem, from Eric Dumazet.
22) Uninitialized last assert time in multicast router code, from Tom
Goff.
23) Skip raw sockets in sock_diag destruction broadcast, from Willem
de Bruijn.
24) Fix link status reporting in thunderx, from Sunil Goutham.
25) Limit resegmentation of retransmit queue so that we do not
retransmit too large GSO frames. From Eric Dumazet.
26) Delay bpf program release after grace period, from Daniel
Borkmann"
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (141 commits)
openvswitch: fix conntrack netlink event delivery
qed: Protect the doorbell BAR with the write barriers.
neigh: Explicitly declare RCU-bh read side critical section in neigh_xmit()
e1000e: keep VLAN interfaces functional after rxvlan off
cfg80211: fix proto in ieee80211_data_to_8023 for frames without LLC header
qlcnic: use the correct ring in qlcnic_83xx_process_rcv_ring_diag()
bpf, perf: delay release of BPF prog after grace period
net: bridge: fix vlan stats continue counter
tcp: do not send too big packets at retransmit time
ibmvnic: fix to use list_for_each_safe() when delete items
net: thunderx: Fix TL4 configuration for secondary Qsets
net: thunderx: Fix link status reporting
net/mlx5e: Reorganize ethtool statistics
net/mlx5e: Fix number of PFC counters reported to ethtool
net/mlx5e: Prevent adding the same vxlan port
net/mlx5e: Check for BlueFlame capability before allocating SQ uar
net/mlx5e: Change enum to better reflect usage
net/mlx5: Add ConnectX-5 PCIe 4.0 to list of supported devices
net/mlx5: Update command strings
net: marvell: Add separate config ANEG function for Marvell 88E1111
...
Pull cgroup fixes from Tejun Heo:
"Three fix patches. Two are for cgroup / css init failure path. The
last one makes css_set_lock irq-safe as the deadline scheduler ends up
calling put_css_set() from irq context"
* 'for-4.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: Disable IRQs while holding css_set_lock
cgroup: set css->id to -1 during init
cgroup: remove redundant cleanup in css_create
Commit dead9f29dd ("perf: Fix race in BPF program unregister") moved
destruction of BPF program from free_event_rcu() callback to __free_event(),
which is problematic if used with tail calls: if prog A is attached as
trace event directly, but at the same time present in a tail call map used
by another trace event program elsewhere, then we need to delay destruction
via RCU grace period since it can still be in use by the program doing the
tail call (the prog first needs to be dropped from the tail call map, then
trace event with prog A attached destroyed, so we get immediate destruction).
Fixes: dead9f29dd ("perf: Fix race in BPF program unregister")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Jann Horn <jann@thejh.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
The only users of audit_get_tty and audit_put_tty are internal to
audit, so move it out of include/linux/audit.h to kernel.h and create
a proper function rather than inlining it. This also reduces kABI
changes.
Suggested-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: line wrapped description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Move the calculations of values after the allocation in case the
allocation fails. This avoids wasting effort in the rare case that it
fails, but more importantly saves us extra logic to release the tty
ref.
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Commit:
fde7d22e01 ("sched/fair: Fix overly small weight for interactive group entities")
did something non-obvious but also did it buggy yet latent.
The problem was exposed for real by a later commit in the v4.7 merge window:
2159197d66 ("sched/core: Enable increased load resolution on 64-bit kernels")
... after which tg->load_avg and cfs_rq->load.weight had different
units (10 bit fixed point and 20 bit fixed point resp.).
Add a comment to explain the use of cfs_rq->load.weight over the
'natural' cfs_rq->avg.load_avg and add scale_load_down() to correct
for the difference in unit.
Since this is (now, as per a previous commit) the only user of
calc_tg_weight(), collapse it.
The effects of this bug should be randomly inconsistent SMP-balancing
of cgroups workloads.
Reported-by: Jirka Hladky <jhladky@redhat.com>
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>
Fixes: 2159197d66 ("sched/core: Enable increased load resolution on 64-bit kernels")
Fixes: fde7d22e01 ("sched/fair: Fix overly small weight for interactive group entities")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Starting with the following commit:
fde7d22e01 ("sched/fair: Fix overly small weight for interactive group entities")
calc_tg_weight() doesn't compute the right value as expected by effective_load().
The difference is in the 'correction' term. In order to ensure \Sum
rw_j >= rw_i we cannot use tg->load_avg directly, since that might be
lagging a correction on the current cfs_rq->avg.load_avg value.
Therefore we use tg->load_avg - cfs_rq->tg_load_avg_contrib +
cfs_rq->avg.load_avg.
Now, per the referenced commit, calc_tg_weight() doesn't use
cfs_rq->avg.load_avg, as is later used in @w, but uses
cfs_rq->load.weight instead.
So stop using calc_tg_weight() and do it explicitly.
The effects of this bug are wake_affine() making randomly
poor choices in cgroup-intense workloads.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org> # v4.3+
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: fde7d22e01 ("sched/fair: Fix overly small weight for interactive group entities")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull scheduler fixes from Thomas Gleixner:
"A couple of scheduler fixes:
- force watchdog reset while processing sysrq-w
- fix a deadlock when enabling trace events in the scheduler
- fixes to the throttled next buddy logic
- fixes for the average accounting (missing serialization and
underflow handling)
- allow kernel threads for fallback to online but not active cpus"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/core: Allow kthreads to fall back to online && !active cpus
sched/fair: Do not announce throttled next buddy in dequeue_task_fair()
sched/fair: Initialize throttle_count for new task-groups lazily
sched/fair: Fix cfs_rq avg tracking underflow
kernel/sysrq, watchdog, sched/core: Reset watchdog on all CPUs while processing sysrq-w
sched/debug: Fix deadlock when enabling sched events
sched/fair: Fix post_init_entity_util_avg() serialization
Pull locking fix from Thomas Gleixner:
"A single fix to address a race in the static key logic"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/static_key: Fix concurrent static_key_slow_inc()
Commit b235beea9e ("Clarify naming of thread info/stack allocators")
breaks the build on some powerpc configs, where THREAD_SIZE < PAGE_SIZE:
kernel/fork.c:235:2: error: implicit declaration of function 'free_thread_stack'
kernel/fork.c:355:8: error: assignment from incompatible pointer type
stack = alloc_thread_stack_node(tsk, node);
^
Fix it by renaming free_stack() to free_thread_stack(), and updating the
return type of alloc_thread_stack_node().
Fixes: b235beea9e ("Clarify naming of thread info/stack allocators")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge misc fixes from Andrew Morton:
"Two weeks worth of fixes here"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (41 commits)
init/main.c: fix initcall_blacklisted on ia64, ppc64 and parisc64
autofs: don't get stuck in a loop if vfs_write() returns an error
mm/page_owner: avoid null pointer dereference
tools/vm/slabinfo: fix spelling mistake: "Ocurrences" -> "Occurrences"
fs/nilfs2: fix potential underflow in call to crc32_le
oom, suspend: fix oom_reaper vs. oom_killer_disable race
ocfs2: disable BUG assertions in reading blocks
mm, compaction: abort free scanner if split fails
mm: prevent KASAN false positives in kmemleak
mm/hugetlb: clear compound_mapcount when freeing gigantic pages
mm/swap.c: flush lru pvecs on compound page arrival
memcg: css_alloc should return an ERR_PTR value on error
memcg: mem_cgroup_migrate() may be called with irq disabled
hugetlb: fix nr_pmds accounting with shared page tables
Revert "mm: disable fault around on emulated access bit architecture"
Revert "mm: make faultaround produce old ptes"
mailmap: add Boris Brezillon's email
mailmap: add Antoine Tenart's email
mm, sl[au]b: add __GFP_ATOMIC to the GFP reclaim mask
mm: mempool: kasan: don't poot mempool objects in quarantine
...
Tetsuo has reported the following potential oom_killer_disable vs.
oom_reaper race:
(1) freeze_processes() starts freezing user space threads.
(2) Somebody (maybe a kenrel thread) calls out_of_memory().
(3) The OOM killer calls mark_oom_victim() on a user space thread
P1 which is already in __refrigerator().
(4) oom_killer_disable() sets oom_killer_disabled = true.
(5) P1 leaves __refrigerator() and enters do_exit().
(6) The OOM reaper calls exit_oom_victim(P1) before P1 can call
exit_oom_victim(P1).
(7) oom_killer_disable() returns while P1 not yet finished
(8) P1 perform IO/interfere with the freezer.
This situation is unfortunate. We cannot move oom_killer_disable after
all the freezable kernel threads are frozen because the oom victim might
depend on some of those kthreads to make a forward progress to exit so
we could deadlock. It is also far from trivial to teach the oom_reaper
to not call exit_oom_victim() because then we would lose a guarantee of
the OOM killer and oom_killer_disable forward progress because
exit_mm->mmput might block and never call exit_oom_victim.
It seems the easiest way forward is to workaround this race by calling
try_to_freeze_tasks again after oom_killer_disable. This will make sure
that all the tasks are frozen or it bails out.
Fixes: 449d777d7a ("mm, oom_reaper: clear TIF_MEMDIE for all tasks queued for oom_reaper")
Link: http://lkml.kernel.org/r/1466597634-16199-1-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We've had the thread info allocated together with the thread stack for
most architectures for a long time (since the thread_info was split off
from the task struct), but that is about to change.
But the patches that move the thread info to be off-stack (and a part of
the task struct instead) made it clear how confused the allocator and
freeing functions are.
Because the common case was that we share an allocation with the thread
stack and the thread_info, the two pointers were identical. That
identity then meant that we would have things like
ti = alloc_thread_info_node(tsk, node);
...
tsk->stack = ti;
which certainly _worked_ (since stack and thread_info have the same
value), but is rather confusing: why are we assigning a thread_info to
the stack? And if we move the thread_info away, the "confusing" code
just gets to be entirely bogus.
So remove all this confusion, and make it clear that we are doing the
stack allocation by renaming and clarifying the function names to be
about the stack. The fact that the thread_info then shares the
allocation is an implementation detail, and not really about the
allocation itself.
This is a pure renaming and type fix: we pass in the same pointer, it's
just that we clarify what the pointer means.
The ia64 code that actually only has one single allocation (for all of
task_struct, thread_info and kernel thread stack) now looks a bit odd,
but since "tsk->stack" is actually not even used there, that oddity
doesn't matter. It would be a separate thing to clean that up, I
intentionally left the ia64 changes as a pure brute-force renaming and
type change.
Acked-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During CPU hotplug, CPU_ONLINE callbacks are run while the CPU is
online but not active. A CPU_ONLINE callback may create or bind a
kthread so that its cpus_allowed mask only allows the CPU which is
being brought online. The kthread may start executing before the CPU
is made active and can end up in select_fallback_rq().
In such cases, the expected behavior is selecting the CPU which is
coming online; however, because select_fallback_rq() only chooses from
active CPUs, it determines that the task doesn't have any viable CPU
in its allowed mask and ends up overriding it to cpu_possible_mask.
CPU_ONLINE callbacks should be able to put kthreads on the CPU which
is coming online. Update select_fallback_rq() so that it follows
cpu_online() rather than cpu_active() for kthreads.
Reported-by: Gautham R Shenoy <ego@linux.vnet.ibm.com>
Tested-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kernel-team@fb.com
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20160616193504.GB3262@mtj.duckdns.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Hierarchy could be already throttled at this point. Throttled next
buddy could trigger a NULL pointer dereference in pick_next_task_fair().
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/146608183552.21905.15924473394414832071.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cgroup created inside throttled group must inherit current throttle_count.
Broken throttle_count allows to nominate throttled entries as a next buddy,
later this leads to null pointer dereference in pick_next_task_fair().
This patch initialize cfs_rq->throttle_count at first enqueue: laziness
allows to skip locking all rq at group creation. Lazy approach also allows
to skip full sub-tree scan at throttling hierarchy (not in this patch).
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
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: bsegall@google.com
Link: http://lkml.kernel.org/r/146608182119.21870.8439834428248129633.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The following scenario is possible:
CPU 1 CPU 2
static_key_slow_inc()
atomic_inc_not_zero()
-> key.enabled == 0, no increment
jump_label_lock()
atomic_inc_return()
-> key.enabled == 1 now
static_key_slow_inc()
atomic_inc_not_zero()
-> key.enabled == 1, inc to 2
return
** static key is wrong!
jump_label_update()
jump_label_unlock()
Testing the static key at the point marked by (**) will follow the
wrong path for jumps that have not been patched yet. This can
actually happen when creating many KVM virtual machines with userspace
LAPIC emulation; just run several copies of the following program:
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/kvm.h>
int main(void)
{
for (;;) {
int kvmfd = open("/dev/kvm", O_RDONLY);
int vmfd = ioctl(kvmfd, KVM_CREATE_VM, 0);
close(ioctl(vmfd, KVM_CREATE_VCPU, 1));
close(vmfd);
close(kvmfd);
}
return 0;
}
Every KVM_CREATE_VCPU ioctl will attempt a static_key_slow_inc() call.
The static key's purpose is to skip NULL pointer checks and indeed one
of the processes eventually dereferences NULL.
As explained in the commit that introduced the bug:
706249c222 ("locking/static_keys: Rework update logic")
jump_label_update() needs key.enabled to be true. The solution adopted
here is to temporarily make key.enabled == -1, and use go down the
slow path when key.enabled <= 0.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org> # v4.3+
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 706249c222 ("locking/static_keys: Rework update logic")
Link: http://lkml.kernel.org/r/1466527937-69798-1-git-send-email-pbonzini@redhat.com
[ Small stylistic edits to the changelog and the code. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
None of the code actually wants a thread_info, it all wants a
task_struct, and it's just converting back and forth between the two
("ti->task" to get the task_struct from the thread_info, and
"task_thread_info(task)" to go the other way).
No semantic change.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
o When trace_printk() is used with a non constant format descriptor,
it adds a NULL pointer into the trace format section, and the code
isn't prepared to deal with it. This bug appeared by a change that
was added in v3.5.
o The ftracetest (selftests section) can't handle testing histograms
when histograms are not configured. Currently it shows that they
fail the test, when they should state that they are unsupported.
This bug was added in the 4.7 merge window with the addition of
the historgram code.
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Merge tag 'trace-v4.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
"Two fixes for the tracing system:
- When trace_printk() is used with a non constant format descriptor,
it adds a NULL pointer into the trace format section, and the code
isn't prepared to deal with it. This bug appeared by a change that
was added in v3.5.
- The ftracetest (selftests section) can't handle testing histograms
when histograms are not configured. Currently it shows that they
fail the test, when they should state that they are unsupported.
This bug was added in the 4.7 merge window with the addition of the
historgram code"
* tag 'trace-v4.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ftracetest: Fix hist unsupported result in hist selftests
tracing: Handle NULL formats in hold_module_trace_bprintk_format()
If a task uses a non constant string for the format parameter in
trace_printk(), then the trace_printk_fmt variable is set to NULL. This
variable is then saved in the __trace_printk_fmt section.
The function hold_module_trace_bprintk_format() checks to see if duplicate
formats are used by modules, and reuses them if so (saves them to the list
if it is new). But this function calls lookup_format() that does a strcmp()
to the value (which is now NULL) and can cause a kernel oops.
This wasn't an issue till 3debb0a9dd ("tracing: Fix trace_printk() to print
when not using bprintk()") which added "__used" to the trace_printk_fmt
variable, and before that, the kernel simply optimized it out (no NULL value
was saved).
The fix is simply to handle the NULL pointer in lookup_format() and have the
caller ignore the value if it was NULL.
Link: http://lkml.kernel.org/r/1464769870-18344-1-git-send-email-zhengjun.xing@intel.com
Reported-by: xingzhen <zhengjun.xing@intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Fixes: 3debb0a9dd ("tracing: Fix trace_printk() to print when not using bprintk()")
Cc: stable@vger.kernel.org # v3.5+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
As per commit:
b7fa30c9cc ("sched/fair: Fix post_init_entity_util_avg() serialization")
> the code generated from update_cfs_rq_load_avg():
>
> if (atomic_long_read(&cfs_rq->removed_load_avg)) {
> s64 r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0);
> sa->load_avg = max_t(long, sa->load_avg - r, 0);
> sa->load_sum = max_t(s64, sa->load_sum - r * LOAD_AVG_MAX, 0);
> removed_load = 1;
> }
>
> turns into:
>
> ffffffff81087064: 49 8b 85 98 00 00 00 mov 0x98(%r13),%rax
> ffffffff8108706b: 48 85 c0 test %rax,%rax
> ffffffff8108706e: 74 40 je ffffffff810870b0 <update_blocked_averages+0xc0>
> ffffffff81087070: 4c 89 f8 mov %r15,%rax
> ffffffff81087073: 49 87 85 98 00 00 00 xchg %rax,0x98(%r13)
> ffffffff8108707a: 49 29 45 70 sub %rax,0x70(%r13)
> ffffffff8108707e: 4c 89 f9 mov %r15,%rcx
> ffffffff81087081: bb 01 00 00 00 mov $0x1,%ebx
> ffffffff81087086: 49 83 7d 70 00 cmpq $0x0,0x70(%r13)
> ffffffff8108708b: 49 0f 49 4d 70 cmovns 0x70(%r13),%rcx
>
> Which you'll note ends up with sa->load_avg -= r in memory at
> ffffffff8108707a.
So I _should_ have looked at other unserialized users of ->load_avg,
but alas. Luckily nikbor reported a similar /0 from task_h_load() which
instantly triggered recollection of this here problem.
Aside from the intermediate value hitting memory and causing problems,
there's another problem: the underflow detection relies on the signed
bit. This reduces the effective width of the variables, IOW its
effectively the same as having these variables be of signed type.
This patch changes to a different means of unsigned underflow
detection to not rely on the signed bit. This allows the variables to
use the 'full' unsigned range. And it does so with explicit LOAD -
STORE to ensure any intermediate value will never be visible in
memory, allowing these unserialized loads.
Note: GCC generates crap code for this, might warrant a look later.
Note2: I say 'full' above, if we end up at U*_MAX we'll still explode;
maybe we should do clamping on add too.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yuyang Du <yuyang.du@intel.com>
Cc: bsegall@google.com
Cc: kernel@kyup.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: steve.muckle@linaro.org
Fixes: 9d89c257df ("sched/fair: Rewrite runnable load and utilization average tracking")
Link: http://lkml.kernel.org/r/20160617091948.GJ30927@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If percpu_ref initialization fails during css_create(), the free path
can end up trying to free css->id of zero. As ID 0 is unused, it
doesn't cause a critical breakage but it does trigger a warning
message. Fix it by setting css->id to -1 from init_and_link_css().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Wenwei Tao <ww.tao0320@gmail.com>
Fixes: 01e586598b ("cgroup: release css->id after css_free")
Cc: stable@vger.kernel.org # v4.0+
Signed-off-by: Tejun Heo <tj@kernel.org>
similar to bpf_perf_event_output() the bpf_perf_event_read() helper
needs to check the type of the perf_event before reading the counter.
Fixes: a43eec3042 ("bpf: introduce bpf_perf_event_output() helper")
Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
The ctx structure passed into bpf programs is different depending on bpf
program type. The verifier incorrectly marked ctx->data and ctx->data_end
access based on ctx offset only. That caused loads in tracing programs
int bpf_prog(struct pt_regs *ctx) { .. ctx->ax .. }
to be incorrectly marked as PTR_TO_PACKET which later caused verifier
to reject the program that was actually valid in tracing context.
Fix this by doing program type specific matching of ctx offsets.
Fixes: 969bf05eb3 ("bpf: direct packet access")
Reported-by: Sasha Goldshtein <goldshtn@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Since commit 49d200deaa ("debugfs: prevent access to removed files'
private data"), a debugfs file's file_operations methods get proxied
through lifetime aware wrappers.
However, only a certain subset of the file_operations members is supported
by debugfs and ->mmap isn't among them -- it appears to be NULL from the
VFS layer's perspective.
This behaviour breaks the /sys/kernel/debug/kcov file introduced
concurrently with commit 5c9a8750a6 ("kernel: add kcov code coverage").
Since that file never gets removed, there is no file removal race and thus,
a lifetime checking proxy isn't needed.
Avoid the proxying for /sys/kernel/debug/kcov by creating it via
debugfs_create_file_unsafe() rather than debugfs_create_file().
Fixes: 49d200deaa ("debugfs: prevent access to removed files' private data")
Fixes: 5c9a8750a6 ("kernel: add kcov code coverage")
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Lengthy output of sysrq-w may take a lot of time on slow serial console.
Currently we reset NMI-watchdog on the current CPU to avoid spurious
lockup messages. Sometimes this doesn't work since softlockup watchdog
might trigger on another CPU which is waiting for an IPI to proceed.
We reset softlockup watchdogs on all CPUs, but we do this only after
listing all tasks, and this may be too late on a busy system.
So, reset watchdogs CPUs earlier, in for_each_process_thread() loop.
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/1465474805-14641-1-git-send-email-aryabinin@virtuozzo.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Merge filesystem stacking fixes from Jann Horn.
* emailed patches from Jann Horn <jannh@google.com>:
sched: panic on corrupted stack end
ecryptfs: forbid opening files without mmap handler
proc: prevent stacking filesystems on top
Until now, hitting this BUG_ON caused a recursive oops (because oops
handling involves do_exit(), which calls into the scheduler, which in
turn raises an oops), which caused stuff below the stack to be
overwritten until a panic happened (e.g. via an oops in interrupt
context, caused by the overwritten CPU index in the thread_info).
Just panic directly.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull perf fixes from Ingo Molnar:
"A handful of tooling fixes, two PMU driver fixes and a cleanup of
redundant code that addresses a security analyzer false positive"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/core: Remove a redundant check
perf/x86/intel/uncore: Remove SBOX support for Broadwell server
perf ctf: Convert invalid chars in a string before set value
perf record: Fix crash when kptr is restricted
perf symbols: Check kptr_restrict for root
perf/x86/intel/rapl: Fix pmus free during cleanup
Pull locking fixes from Ingo Molnar:
"Misc fixes:
- a file-based futex fix
- one more spin_unlock_wait() fix
- a ww-mutex deadlock detection improvement/fix
- and a raw_read_seqcount_latch() barrier fix"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
futex: Calculate the futex key based on a tail page for file-based futexes
locking/qspinlock: Fix spin_unlock_wait() some more
locking/ww_mutex: Report recursive ww_mutex locking early
locking/seqcount: Re-fix raw_read_seqcount_latch()
Pull networking fixes from David Miller:
1) nfnetlink timestamp taken from wrong skb, fix from Florian Westphal.
2) Revert some msleep conversions in rtlwifi as these spots are in
atomic context, from Larry Finger.
3) Validate that NFTA_SET_TABLE attribute is actually specified when we
call nf_tables_getset(). From Phil Turnbull.
4) Don't do mdio_reset in stmmac driver with spinlock held as that can
sleep, from Vincent Palatin.
5) sk_filter() does things other than run a BPF filter, so we should
not elide it's call just because sk->sk_filter is NULL. Fix from
Eric Dumazet.
6) Fix missing backlog updates in several packet schedulers, from Cong
Wang.
7) bnx2x driver should allow VLAN add/remove while the interface is
down, from Michal Schmidt.
8) Several RDS/TCP race fixes from Sowmini Varadhan.
9) fq_codel scheduler doesn't return correct queue length in dumps,
from Eric Dumazet.
10) Fix TCP stats for tail loss probe and early retransmit in ipv6, from
Yuchung Cheng.
11) Properly initialize udp_tunnel_socket_cfg in l2tp_tunnel_create(),
from Guillaume Nault.
12) qfq scheduler leaks SKBs if a kzalloc fails, fix from Florian
Westphal.
13) sock_fprog passed into PACKET_FANOUT_DATA needs compat handling,
from Willem de Bruijn.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (85 commits)
vmxnet3: segCnt can be 1 for LRO packets
packet: compat support for sock_fprog
stmmac: fix parameter to dwmac4_set_umac_addr()
net/mlx5e: Fix blue flame quota logic
net/mlx5e: Use ndo_stop explicitly at shutdown flow
net/mlx5: E-Switch, always set mc_promisc for allmulti vports
net/mlx5: E-Switch, Modify node guid on vf set MAC
net/mlx5: E-Switch, Fix vport enable flow
net/mlx5: E-Switch, Use the correct error check on returned pointers
net/mlx5: E-Switch, Use the correct free() function
net/mlx5: Fix E-Switch flow steering capabilities check
net/mlx5: Fix flow steering NIC capabilities check
net/mlx5: Fix root flow table update
net/mlx5: Fix MLX5_CMD_OP_MAX to be defined correctly
net/mlx5: Fix masking of reserved bits in XRCD number
net/mlx5: Fix the size of modify QP mailbox
mlxsw: spectrum: Don't sleep during ndo_get_phys_port_name()
mlxsw: spectrum: Make split flow match firmware requirements
wext: Fix 32 bit iwpriv compatibility issue with 64 bit Kernel
cfg80211: remove get/set antenna and tx power warnings
...
- Fix two intel_pstate initialization issues, one of which was
introduced during the 4.4 cycle (Srinivas Pandruvada).
- Fix kernel build with CONFIG_UBSAN set and CONFIG_CPU_IDLE
unset (Catalin Marinas).
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Merge tag 'pm-4.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management fixes from Rafael Wysocki:
"Stable-candidate fixes for the intel_pstate driver and the cpuidle
core.
Specifics:
- Fix two intel_pstate initialization issues, one of which was
introduced during the 4.4 cycle (Srinivas Pandruvada)
- Fix kernel build with CONFIG_UBSAN set and CONFIG_CPU_IDLE unset
(Catalin Marinas)"
* tag 'pm-4.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
cpufreq: intel_pstate: Fix ->set_policy() interface for no_turbo
cpufreq: intel_pstate: Fix code ordering in intel_pstate_set_policy()
cpuidle: Do not access cpuidle_devices when !CONFIG_CPU_IDLE
* pm-cpufreq-fixes:
cpufreq: intel_pstate: Fix ->set_policy() interface for no_turbo
cpufreq: intel_pstate: Fix code ordering in intel_pstate_set_policy()
* pm-cpuidle:
cpuidle: Do not access cpuidle_devices when !CONFIG_CPU_IDLE
Mike Galbraith reported that the LTP test case futex_wake04 was broken
by commit 65d8fc777f ("futex: Remove requirement for lock_page()
in get_futex_key()").
This test case uses futexes backed by hugetlbfs pages and so there is an
associated inode with a futex stored on such pages. The problem is that
the key is being calculated based on the head page index of the hugetlbfs
page and not the tail page.
Prior to the optimisation, the page lock was used to stabilise mappings and
pin the inode is file-backed which is overkill. If the page was a compound
page, the head page was automatically looked up as part of the page lock
operation but the tail page index was used to calculate the futex key.
After the optimisation, the compound head is looked up early and the page
lock is only relied upon to identify truncated pages, special pages or a
shmem page moving to swapcache. The head page is looked up because without
the page lock, special care has to be taken to pin the inode correctly.
However, the tail page is still required to calculate the futex key so
this patch records the tail page.
On vanilla 4.6, the output of the test case is;
futex_wake04 0 TINFO : Hugepagesize 2097152
futex_wake04 1 TFAIL : futex_wake04.c:126: Bug: wait_thread2 did not wake after 30 secs.
With the patch applied
futex_wake04 0 TINFO : Hugepagesize 2097152
futex_wake04 1 TPASS : Hi hydra, thread2 awake!
Fixes: 65d8fc777f "futex: Remove requirement for lock_page() in get_futex_key()"
Reported-and-tested-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20160608132522.GM2469@suse.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The 'schedstats=enable' option doesn't work, and also produces the
following warning during boot:
WARNING: CPU: 0 PID: 0 at /home/jpoimboe/git/linux/kernel/jump_label.c:61 static_key_slow_inc+0x8c/0xa0
static_key_slow_inc used before call to jump_label_init
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 4.7.0-rc1+ #25
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.1-20150318_183358- 04/01/2014
0000000000000086 3ae3475a4bea95d4 ffffffff81e03da8 ffffffff8143fc83
ffffffff81e03df8 0000000000000000 ffffffff81e03de8 ffffffff810b1ffb
0000003d00000096 ffffffff823514d0 ffff88007ff197c8 0000000000000000
Call Trace:
[<ffffffff8143fc83>] dump_stack+0x85/0xc2
[<ffffffff810b1ffb>] __warn+0xcb/0xf0
[<ffffffff810b207f>] warn_slowpath_fmt+0x5f/0x80
[<ffffffff811e9c0c>] static_key_slow_inc+0x8c/0xa0
[<ffffffff810e07c6>] static_key_enable+0x16/0x40
[<ffffffff8216d633>] setup_schedstats+0x29/0x94
[<ffffffff82148a05>] unknown_bootoption+0x89/0x191
[<ffffffff810d8617>] parse_args+0x297/0x4b0
[<ffffffff82148d61>] start_kernel+0x1d8/0x4a9
[<ffffffff8214897c>] ? set_init_arg+0x55/0x55
[<ffffffff82148120>] ? early_idt_handler_array+0x120/0x120
[<ffffffff821482db>] x86_64_start_reservations+0x2f/0x31
[<ffffffff82148427>] x86_64_start_kernel+0x14a/0x16d
The problem is that it tries to update the 'sched_schedstats' static key
before jump labels have been initialized.
Changing jump_label_init() to be called earlier before
parse_early_param() wouldn't fix it: it would still fail trying to
poke_text() because mm isn't yet initialized.
Instead, just create a temporary '__sched_schedstats' variable which can
be copied to the static key later during sched_init() after jump labels
have been initialized.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: cb2517653f ("sched/debug: Make schedstats a runtime tunable that is disabled by default")
Link: http://lkml.kernel.org/r/453775fe3433bed65731a583e228ccea806d18cd.1465322027.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit:
cb2517653f ("sched/debug: Make schedstats a runtime tunable that is disabled by default")
... introduced a bug when CONFIG_SCHEDSTATS is enabled and the
runtime tunable is disabled (which is the default).
The wait-time, sum-exec, and sum-sleep fields are missing from the
/proc/sched_debug file in the runnable_tasks section.
Fix it with a new schedstat_val() macro which returns the field value
when schedstats is enabled and zero otherwise. The macro works with
both SCHEDSTATS and !SCHEDSTATS. I put the macro in stats.h since it
might end up being useful in other places.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: cb2517653f ("sched/debug: Make schedstats a runtime tunable that is disabled by default")
Link: http://lkml.kernel.org/r/bcda7c2790cf2ccbe586a28c02dd7b6fe7749a2b.1464994423.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is no way to end up in _free_event() with event::pmu being NULL.
The latter is initialized in event allocation path and remains set
forever. In case of allocation failure, the error path doesn't use
_free_event().
Having the check, however, suggests that it is possible to have a
event::pmu==NULL situation in _free_event() and confuses the robots.
This patch gets rid of the check.
Reported-by: Dan Carpenter <dan.carpenter@oracle.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: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: eranian@google.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/1465303455-26032-1-git-send-email-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
While this prior commit:
54cf809b95 ("locking,qspinlock: Fix spin_is_locked() and spin_unlock_wait()")
... fixes spin_is_locked() and spin_unlock_wait() for the usage
in ipc/sem and netfilter, it does not in fact work right for the
usage in task_work and futex.
So while the 2 locks crossed problem:
spin_lock(A) spin_lock(B)
if (!spin_is_locked(B)) spin_unlock_wait(A)
foo() foo();
... works with the smp_mb() injected by both spin_is_locked() and
spin_unlock_wait(), this is not sufficient for:
flag = 1;
smp_mb(); spin_lock()
spin_unlock_wait() if (!flag)
// add to lockless list
// iterate lockless list
... because in this scenario, the store from spin_lock() can be delayed
past the load of flag, uncrossing the variables and loosing the
guarantee.
This patch reworks spin_is_locked() and spin_unlock_wait() to work in
both cases by exploiting the observation that while the lock byte
store can be delayed, the contender must have registered itself
visibly in other state contained in the word.
It also allows for architectures to override both functions, as PPC
and ARM64 have an additional issue for which we currently have no
generic solution.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Giovanni Gherdovich <ggherdovich@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <waiman.long@hpe.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: stable@vger.kernel.org # v4.2 and later
Fixes: 54cf809b95 ("locking,qspinlock: Fix spin_is_locked() and spin_unlock_wait()")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In bpf_perf_event_read() and bpf_perf_event_output(), we must use
READ_ONCE() for fetching the struct file pointer, which could get
updated concurrently, so we must prevent the compiler from potential
refetching.
We already do this with tail calls for fetching the related bpf_prog,
but not so on stored perf events. Semantics for both are the same
with regards to updates.
Fixes: a43eec3042 ("bpf: introduce bpf_perf_event_output() helper")
Fixes: 35578d7984 ("bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
