From: David Rientjes <rientjes@google.com>
To: Suren Baghdasaryan <surenb@google.com>
Cc: akpm@linux-foundation.org, mhocko@suse.com, hannes@cmpxchg.org,
hillf.zj@alibaba-inc.com, minchan@kernel.org,
mgorman@techsingularity.net, ying.huang@intel.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
timmurray@google.com, tkjos@google.com
Subject: Re: [PATCH v2] mm: terminate shrink_slab loop if signal is pending
Date: Fri, 8 Dec 2017 13:02:20 -0800 (PST) [thread overview]
Message-ID: <alpine.DEB.2.10.1712081259520.47087@chino.kir.corp.google.com> (raw)
In-Reply-To: <20171208012305.83134-1-surenb@google.com>
On Thu, 7 Dec 2017, Suren Baghdasaryan wrote:
> Slab shrinkers can be quite time consuming and when signal
> is pending they can delay handling of the signal. If fatal
> signal is pending there is no point in shrinking that process
> since it will be killed anyway. This change checks for pending
> fatal signals inside shrink_slab loop and if one is detected
> terminates this loop early.
>
I've proposed a similar patch in the past, but for a check on TIF_MEMDIE,
which would today be a tsk_is_oom_victim(current), since we had observed
lengthy stalls in reclaim that would have been prevented if the oom victim
had exited out, returned back to the page allocator, allocated with
ALLOC_NO_WATERMARKS, and proceeded to quickly exit.
I'm not sure that all fatal_signal_pending() tasks should get the same
treatment, but I understand the point that the task is killed and should
free memory when it fully exits. How much memory is unknown.
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
>
> ---
> V2:
> Sergey Senozhatsky:
> - Fix missing parentheses
> ---
> mm/vmscan.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index c02c850ea349..28e4bdc72c16 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -486,6 +486,13 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
> .memcg = memcg,
> };
>
> + /*
> + * We are about to die and free our memory.
> + * Stop shrinking which might delay signal handling.
> + */
> + if (unlikely(fatal_signal_pending(current)))
> + break;
> +
> /*
> * If kernel memory accounting is disabled, we ignore
> * SHRINKER_MEMCG_AWARE flag and call all shrinkers
next prev parent reply other threads:[~2017-12-08 21:02 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-08 1:23 [PATCH v2] mm: terminate shrink_slab loop if signal is pending Suren Baghdasaryan
2017-12-08 8:22 ` Michal Hocko
2017-12-08 11:36 ` Tetsuo Handa
2017-12-08 11:48 ` Michal Hocko
2017-12-08 14:03 ` Tetsuo Handa
2017-12-08 18:06 ` Suren Baghdasaryan
2017-12-09 8:08 ` Tetsuo Handa
2017-12-10 10:17 ` Michal Hocko
2017-12-11 21:05 ` Suren Baghdasaryan
2017-12-10 10:13 ` Michal Hocko
2017-12-10 11:37 ` Tetsuo Handa
2017-12-11 21:12 ` Suren Baghdasaryan
2017-12-08 21:02 ` David Rientjes [this message]
2017-12-09 3:16 ` Suren Baghdasaryan
2017-12-09 12:44 ` Tetsuo Handa
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