* [PATCH v3] perf/core: fix mlock accounting in perf_mmap()
@ 2020-01-23 18:11 Song Liu
2020-01-24 9:25 ` Alexander Shishkin
2020-01-29 11:32 ` [tip: perf/urgent] perf/core: Fix " tip-bot2 for Song Liu
0 siblings, 2 replies; 5+ messages in thread
From: Song Liu @ 2020-01-23 18:11 UTC (permalink / raw)
To: linux-kernel
Cc: kernel-team, Song Liu, Alexander Shishkin,
Arnaldo Carvalho de Melo, Jiri Olsa, Peter Zijlstra
Eecreasing sysctl_perf_event_mlock between two consecutive perf_mmap()s of
a perf ring buffer may lead to an integer underflow in locked memory
accounting. This may lead to the undesired behaviors, such as failures in
BPF map creation.
Address this by adjusting the accounting logic to take into account the
possibility that the amount of already locked memory may exceed the
current limit.
Fixes: c4b75479741c ("perf/core: Make the mlock accounting simple again")
Signed-off-by: Song Liu <songliubraving@fb.com>
Suggested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
---
kernel/events/core.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index e543bab787e5..fdb7f7ef380c 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5917,7 +5917,15 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
*/
user_lock_limit *= num_online_cpus();
- user_locked = atomic_long_read(&user->locked_vm) + user_extra;
+ user_locked = atomic_long_read(&user->locked_vm);
+
+ /*
+ * sysctl_perf_event_mlock may have changed, so that
+ * user->locked_vm > user_lock_limit
+ */
+ if (user_locked > user_lock_limit)
+ user_locked = user_lock_limit;
+ user_locked += user_extra;
if (user_locked > user_lock_limit) {
/*
--
2.17.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH v3] perf/core: fix mlock accounting in perf_mmap()
2020-01-23 18:11 [PATCH v3] perf/core: fix mlock accounting in perf_mmap() Song Liu
@ 2020-01-24 9:25 ` Alexander Shishkin
2020-01-24 21:28 ` Song Liu
2020-01-29 11:32 ` [tip: perf/urgent] perf/core: Fix " tip-bot2 for Song Liu
1 sibling, 1 reply; 5+ messages in thread
From: Alexander Shishkin @ 2020-01-24 9:25 UTC (permalink / raw)
To: Song Liu, linux-kernel
Cc: kernel-team, Song Liu, Arnaldo Carvalho de Melo, Jiri Olsa,
Peter Zijlstra, alexander.shishkin
Song Liu <songliubraving@fb.com> writes:
> Eecreasing sysctl_perf_event_mlock between two consecutive perf_mmap()s of
Typo: "Decreasing".
> a perf ring buffer may lead to an integer underflow in locked memory
> accounting. This may lead to the undesired behaviors, such as failures in
> BPF map creation.
>
> Address this by adjusting the accounting logic to take into account the
> possibility that the amount of already locked memory may exceed the
> current limit.
>
> Fixes: c4b75479741c ("perf/core: Make the mlock accounting simple again")
> Signed-off-by: Song Liu <songliubraving@fb.com>
> Suggested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
Other than that,
Acked-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Thanks,
--
Alex
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH v3] perf/core: fix mlock accounting in perf_mmap()
2020-01-24 9:25 ` Alexander Shishkin
@ 2020-01-24 21:28 ` Song Liu
2020-01-24 23:26 ` Peter Zijlstra
0 siblings, 1 reply; 5+ messages in thread
From: Song Liu @ 2020-01-24 21:28 UTC (permalink / raw)
To: Alexander Shishkin
Cc: linux-kernel, Kernel Team, Arnaldo Carvalho de Melo, Jiri Olsa,
Peter Zijlstra
Thanks Alex!
> On Jan 24, 2020, at 1:25 AM, Alexander Shishkin <alexander.shishkin@linux.intel.com> wrote:
>
> Song Liu <songliubraving@fb.com> writes:
>
>> Eecreasing sysctl_perf_event_mlock between two consecutive perf_mmap()s of
>
> Typo: "Decreasing".
Peter, could you please fix this typo when you apply the patch? I guess
it is not necessary to spam the list with a v4 just for this typo.
Thanks,
Song
>
>> a perf ring buffer may lead to an integer underflow in locked memory
>> accounting. This may lead to the undesired behaviors, such as failures in
>> BPF map creation.
>>
>> Address this by adjusting the accounting logic to take into account the
>> possibility that the amount of already locked memory may exceed the
>> current limit.
>>
>> Fixes: c4b75479741c ("perf/core: Make the mlock accounting simple again")
>> Signed-off-by: Song Liu <songliubraving@fb.com>
>> Suggested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
>> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
>> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
>> Cc: Jiri Olsa <jolsa@kernel.org>
>> Cc: Peter Zijlstra <peterz@infradead.org>
>
> Other than that,
>
> Acked-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
>
> Thanks,
> --
> Alex
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH v3] perf/core: fix mlock accounting in perf_mmap()
2020-01-24 21:28 ` Song Liu
@ 2020-01-24 23:26 ` Peter Zijlstra
0 siblings, 0 replies; 5+ messages in thread
From: Peter Zijlstra @ 2020-01-24 23:26 UTC (permalink / raw)
To: Song Liu
Cc: Alexander Shishkin, linux-kernel, Kernel Team,
Arnaldo Carvalho de Melo, Jiri Olsa
On Fri, Jan 24, 2020 at 09:28:26PM +0000, Song Liu wrote:
> Thanks Alex!
>
> > On Jan 24, 2020, at 1:25 AM, Alexander Shishkin <alexander.shishkin@linux.intel.com> wrote:
> >
> > Song Liu <songliubraving@fb.com> writes:
> >
> >> Eecreasing sysctl_perf_event_mlock between two consecutive perf_mmap()s of
> >
> > Typo: "Decreasing".
>
> Peter, could you please fix this typo when you apply the patch? I guess
> it is not necessary to spam the list with a v4 just for this typo.
Done!
^ permalink raw reply [flat|nested] 5+ messages in thread
* [tip: perf/urgent] perf/core: Fix mlock accounting in perf_mmap()
2020-01-23 18:11 [PATCH v3] perf/core: fix mlock accounting in perf_mmap() Song Liu
2020-01-24 9:25 ` Alexander Shishkin
@ 2020-01-29 11:32 ` tip-bot2 for Song Liu
1 sibling, 0 replies; 5+ messages in thread
From: tip-bot2 for Song Liu @ 2020-01-29 11:32 UTC (permalink / raw)
To: linux-tip-commits
Cc: Alexander Shishkin, Song Liu, Peter Zijlstra (Intel),
Ingo Molnar, stable, x86, LKML
The following commit has been merged into the perf/urgent branch of tip:
Commit-ID: 003461559ef7a9bd0239bae35a22ad8924d6e9ad
Gitweb: https://git.kernel.org/tip/003461559ef7a9bd0239bae35a22ad8924d6e9ad
Author: Song Liu <songliubraving@fb.com>
AuthorDate: Thu, 23 Jan 2020 10:11:46 -08:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 28 Jan 2020 21:20:18 +01:00
perf/core: Fix mlock accounting in perf_mmap()
Decreasing sysctl_perf_event_mlock between two consecutive perf_mmap()s of
a perf ring buffer may lead to an integer underflow in locked memory
accounting. This may lead to the undesired behaviors, such as failures in
BPF map creation.
Address this by adjusting the accounting logic to take into account the
possibility that the amount of already locked memory may exceed the
current limit.
Fixes: c4b75479741c ("perf/core: Make the mlock accounting simple again")
Suggested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: <stable@vger.kernel.org>
Acked-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Link: https://lkml.kernel.org/r/20200123181146.2238074-1-songliubraving@fb.com
---
kernel/events/core.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 2173c23..2d9aeba 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5916,7 +5916,15 @@ accounting:
*/
user_lock_limit *= num_online_cpus();
- user_locked = atomic_long_read(&user->locked_vm) + user_extra;
+ user_locked = atomic_long_read(&user->locked_vm);
+
+ /*
+ * sysctl_perf_event_mlock may have changed, so that
+ * user->locked_vm > user_lock_limit
+ */
+ if (user_locked > user_lock_limit)
+ user_locked = user_lock_limit;
+ user_locked += user_extra;
if (user_locked > user_lock_limit) {
/*
^ permalink raw reply related [flat|nested] 5+ messages in thread
end of thread, other threads:[~2020-01-29 11:33 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-01-23 18:11 [PATCH v3] perf/core: fix mlock accounting in perf_mmap() Song Liu
2020-01-24 9:25 ` Alexander Shishkin
2020-01-24 21:28 ` Song Liu
2020-01-24 23:26 ` Peter Zijlstra
2020-01-29 11:32 ` [tip: perf/urgent] perf/core: Fix " tip-bot2 for Song Liu
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