linux-stable.git/kernel, branch v5.4.176

tracing: Don't inc err_log entry count if entry allocation fails

2022-02-01T16:24:34+00:00

commit 67ab5eb71b37b55f7c5522d080a1b42823351776 upstream.

tr->n_err_log_entries should only be increased if entry allocation
succeeds.

Doing it when it fails won't cause any problems other than wasting an
entry, but should be fixed anyway.

Link: https://lkml.kernel.org/r/cad1ab28f75968db0f466925e7cba5970cec6c29.1643319703.git.zanussi@kernel.org

Cc: stable@vger.kernel.org
Fixes: 2f754e771b1a6 ("tracing: Don't inc err_log entry count if entry allocation fails")
Signed-off-by: Tom Zanussi 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

tracing/histogram: Fix a potential memory leak for kstrdup()

2022-02-01T16:24:34+00:00

commit e629e7b525a179e29d53463d992bdee759c950fb upstream.

kfree() is missing on an error path to free the memory allocated by
kstrdup():

  p = param = kstrdup(data->params[i], GFP_KERNEL);

So it is better to free it via kfree(p).

Link: https://lkml.kernel.org/r/tencent_C52895FD37802832A3E5B272D05008866F0A@qq.com

Cc: stable@vger.kernel.org
Fixes: d380dcde9a07c ("tracing: Fix now invalid var_ref_vals assumption in trace action")
Signed-off-by: Xiaoke Wang 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

PM: wakeup: simplify the output logic of pm_show_wakelocks()

2022-02-01T16:24:34+00:00

commit c9d967b2ce40d71e968eb839f36c936b8a9cf1ea upstream.

The buffer handling in pm_show_wakelocks() is tricky, and hopefully
correct.  Ensure it really is correct by using sysfs_emit_at() which
handles all of the tricky string handling logic in a PAGE_SIZE buffer
for us automatically as this is a sysfs file being read from.

Reviewed-by: Lee Jones 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

rcu: Tighten rcu_advance_cbs_nowake() checks

2022-01-29T09:25:09+00:00

commit 614ddad17f22a22e035e2ea37a04815f50362017 upstream.

Currently, rcu_advance_cbs_nowake() checks that a grace period is in
progress, however, that grace period could end just after the check.
This commit rechecks that a grace period is still in progress while
holding the rcu_node structure's lock.  The grace period cannot end while
the current CPU's rcu_node structure's ->lock is held, thus avoiding
false positives from the WARN_ON_ONCE().

As Daniel Vacek noted, it is not necessary for the rcu_node structure
to have a CPU that has not yet passed through its quiescent state.

Tested-by: Guillaume Morin 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Greg Kroah-Hartman

tracing/kprobes: 'nmissed' not showed correctly for kretprobe

2022-01-27T08:19:49+00:00

commit dfea08a2116fe327f79d8f4d4b2cf6e0c88be11f upstream.

The 'nmissed' column of the 'kprobe_profile' file for kretprobe is
not showed correctly, kretprobe can be skipped by two reasons,
shortage of kretprobe_instance which is counted by tk->rp.nmissed,
and kprobe itself is missed by some reason, so to show the sum.

Link: https://lkml.kernel.org/r/20220107150242.5019-1-xyz.sun.ok@gmail.com

Cc: stable@vger.kernel.org
Fixes: 4a846b443b4e ("tracing/kprobes: Cleanup kprobe tracer code")
Acked-by: Masami Hiramatsu 
Signed-off-by: Xiangyang Zhang 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

cputime, cpuacct: Include guest time in user time in cpuacct.stat

2022-01-27T08:19:49+00:00

commit 9731698ecb9c851f353ce2496292ff9fcea39dff upstream.

cpuacct.stat in no-root cgroups shows user time without guest time
included int it. This doesn't match with user time shown in root
cpuacct.stat and /proc//stat. This also affects cgroup2's cpu.stat
in the same way.

Make account_guest_time() to add user time to cgroup's cpustat to
fix this.

Fixes: ef12fefabf94 ("cpuacct: add per-cgroup utime/stime statistics")
Signed-off-by: Andrey Ryabinin 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Daniel Jordan 
Acked-by: Tejun Heo 
Cc: 
Link: https://lore.kernel.org/r/20211115164607.23784-1-arbn@yandex-team.com
Signed-off-by: Greg Kroah-Hartman

audit: ensure userspace is penalized the same as the kernel when under pressure

2022-01-27T08:19:44+00:00

[ Upstream commit 8f110f530635af44fff1f4ee100ecef0bac62510 ]

Due to the audit control mutex necessary for serializing audit
userspace messages we haven't been able to block/penalize userspace
processes that attempt to send audit records while the system is
under audit pressure.  The result is that privileged userspace
applications have a priority boost with respect to audit as they are
not bound by the same audit queue throttling as the other tasks on
the system.

This patch attempts to restore some balance to the system when under
audit pressure by blocking these privileged userspace tasks after
they have finished their audit processing, and dropped the audit
control mutex, but before they return to userspace.

Reported-by: Gaosheng Cui 
Tested-by: Gaosheng Cui 
Reviewed-by: Richard Guy Briggs 
Signed-off-by: Paul Moore 
Signed-off-by: Sasha Levin

rcu/exp: Mark current CPU as exp-QS in IPI loop second pass

2022-01-27T08:19:33+00:00

[ Upstream commit 81f6d49cce2d2fe507e3fddcc4a6db021d9c2e7b ]

Expedited RCU grace periods invoke sync_rcu_exp_select_node_cpus(), which
takes two passes over the leaf rcu_node structure's CPUs.  The first
pass gathers up the current CPU and CPUs that are in dynticks idle mode.
The workqueue will report a quiescent state on their behalf later.
The second pass sends IPIs to the rest of the CPUs, but excludes the
current CPU, incorrectly assuming it has been included in the first
pass's list of CPUs.

Unfortunately the current CPU may have changed between the first and
second pass, due to the fact that the various rcu_node structures'
->lock fields have been dropped, thus momentarily enabling preemption.
This means that if the second pass's CPU was not on the first pass's
list, it will be ignored completely.  There will be no IPI sent to
it, and there will be no reporting of quiescent states on its behalf.
Unfortunately, the expedited grace period will nevertheless be waiting
for that CPU to report a quiescent state, but with that CPU having no
reason to believe that such a report is needed.

The result will be an expedited grace period stall.

Fix this by no longer excluding the current CPU from consideration during
the second pass.

Fixes: b9ad4d6ed18e ("rcu: Avoid self-IPI in sync_rcu_exp_select_node_cpus()")
Reviewed-by: Neeraj Upadhyay 
Signed-off-by: Frederic Weisbecker 
Cc: Uladzislau Rezki 
Cc: Neeraj Upadhyay 
Cc: Boqun Feng 
Cc: Josh Triplett 
Cc: Joel Fernandes 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Sasha Levin

sched/rt: Try to restart rt period timer when rt runtime exceeded

2022-01-27T08:19:33+00:00

[ Upstream commit 9b58e976b3b391c0cf02e038d53dd0478ed3013c ]

When rt_runtime is modified from -1 to a valid control value, it may
cause the task to be throttled all the time. Operations like the following
will trigger the bug. E.g:

  1. echo -1 > /proc/sys/kernel/sched_rt_runtime_us
  2. Run a FIFO task named A that executes while(1)
  3. echo 950000 > /proc/sys/kernel/sched_rt_runtime_us

When rt_runtime is -1, The rt period timer will not be activated when task
A enqueued. And then the task will be throttled after setting rt_runtime to
950,000. The task will always be throttled because the rt period timer is
not activated.

Fixes: d0b27fa77854 ("sched: rt-group: synchonised bandwidth period")
Reported-by: Hulk Robot 
Signed-off-by: Li Hua 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20211203033618.11895-1-hucool.lihua@huawei.com
Signed-off-by: Sasha Levin

perf: Protect perf_guest_cbs with RCU

2022-01-20T08:19:18+00:00

commit ff083a2d972f56bebfd82409ca62e5dfce950961 upstream.

Protect perf_guest_cbs with RCU to fix multiple possible errors.  Luckily,
all paths that read perf_guest_cbs already require RCU protection, e.g. to
protect the callback chains, so only the direct perf_guest_cbs touchpoints
need to be modified.

Bug #1 is a simple lack of WRITE_ONCE/READ_ONCE behavior to ensure
perf_guest_cbs isn't reloaded between a !NULL check and a dereference.
Fixed via the READ_ONCE() in rcu_dereference().

Bug #2 is that on weakly-ordered architectures, updates to the callbacks
themselves are not guaranteed to be visible before the pointer is made
visible to readers.  Fixed by the smp_store_release() in
rcu_assign_pointer() when the new pointer is non-NULL.

Bug #3 is that, because the callbacks are global, it's possible for
readers to run in parallel with an unregisters, and thus a module
implementing the callbacks can be unloaded while readers are in flight,
resulting in a use-after-free.  Fixed by a synchronize_rcu() call when
unregistering callbacks.

Bug #1 escaped notice because it's extremely unlikely a compiler will
reload perf_guest_cbs in this sequence.  perf_guest_cbs does get reloaded
for future derefs, e.g. for ->is_user_mode(), but the ->is_in_guest()
guard all but guarantees the consumer will win the race, e.g. to nullify
perf_guest_cbs, KVM has to completely exit the guest and teardown down
all VMs before KVM start its module unload / unregister sequence.  This
also makes it all but impossible to encounter bug #3.

Bug #2 has not been a problem because all architectures that register
callbacks are strongly ordered and/or have a static set of callbacks.

But with help, unloading kvm_intel can trigger bug #1 e.g. wrapping
perf_guest_cbs with READ_ONCE in perf_misc_flags() while spamming
kvm_intel module load/unload leads to:

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: 0000 [#1] PREEMPT SMP
  CPU: 6 PID: 1825 Comm: stress Not tainted 5.14.0-rc2+ #459
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
  RIP: 0010:perf_misc_flags+0x1c/0x70
  Call Trace:
   perf_prepare_sample+0x53/0x6b0
   perf_event_output_forward+0x67/0x160
   __perf_event_overflow+0x52/0xf0
   handle_pmi_common+0x207/0x300
   intel_pmu_handle_irq+0xcf/0x410
   perf_event_nmi_handler+0x28/0x50
   nmi_handle+0xc7/0x260
   default_do_nmi+0x6b/0x170
   exc_nmi+0x103/0x130
   asm_exc_nmi+0x76/0xbf

Fixes: 39447b386c84 ("perf: Enhance perf to allow for guest statistic collection from host")
Signed-off-by: Sean Christopherson 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Paolo Bonzini 
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211111020738.2512932-2-seanjc@google.com
Signed-off-by: Greg Kroah-Hartman