From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
To: Song Liu <songliubraving@fb.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Jiri Olsa <jolsa@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
alexander.shishkin@linux.intel.com
Subject: Re: [PATCH] perf/core: fix mlock accounting in perf_mmap()
Date: Thu, 23 Jan 2020 11:19:44 +0200 [thread overview]
Message-ID: <875zh2bkcv.fsf@ashishki-desk.ger.corp.intel.com> (raw)
In-Reply-To: <79CAEE07-57BC-4915-A812-DD99AAF1B809@fb.com>
Song Liu <songliubraving@fb.com> writes:
>> On Jan 20, 2020, at 12:24 AM, Alexander Shishkin <alexander.shishkin@linux.intel.com> wrote:
>>
>> Song Liu <songliubraving@fb.com> writes:
>>
>>> sysctl_perf_event_mlock and user->locked_vm can change value
>>> independently, so we can't guarantee:
>>>
>>> user->locked_vm <= user_lock_limit
>>
>> This means: if the sysctl got sufficiently decreased, so that the
>> existing locked_vm exceeds it, we need to deal with the overflow, right?
>
> Reducing sysctl is one way to generate the overflow. Another way is to
> call setrlimit() from user space to allow bigger user->locked_vm.
You mean RLIMIT_MEMLOCK? That's a limit on mm->pinned_vm. Doesn't affect
user->locked_vm.
Regards,
--
Alex
next prev parent reply other threads:[~2020-01-23 9:19 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-17 23:45 [PATCH] perf/core: fix mlock accounting in perf_mmap() Song Liu
2020-01-20 8:24 ` Alexander Shishkin
2020-01-21 18:55 ` Song Liu
2020-01-23 9:19 ` Alexander Shishkin [this message]
2020-01-23 17:24 ` Song Liu
2020-01-21 19:35 ` Song Liu
2020-01-22 8:50 ` Alexander Shishkin
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