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Re: [PATCH v7] mm: Add memory allocation watchdog kernel thread.

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Andrew, do you have any questions on this patch?
I really need this patch for finding bugs which MM people overlook.

Tetsuo Handa wrote:
> This patch adds a watchdog which periodically reports number of memory
> allocating tasks, dying tasks and OOM victim tasks when some task is
> spending too long time inside __alloc_pages_slowpath(). This patch also
> serves as a hook for obtaining additional information using SystemTap
> (e.g. examine other variables using printk(), capture a crash dump by
> calling panic()) by triggering a callback only when a stall is detected.
> Ability to take administrator-controlled actions based on some threshold
> is a big advantage gained by introducing a state tracking.
> 
> Commit 63f53dea0c9866e9 ("mm: warn about allocations which stall for
> too long") was a great step for reducing possibility of silent hang up
> problem caused by memory allocation stalls [1]. However, there are
> reports of long stalls (e.g. [2] is over 30 minutes!) and lockups (e.g.
> [3] is an "unable to invoke the OOM killer due to !__GFP_FS allocation"
> lockup problem) where this patch is more useful than that commit, for
> this patch can report possibly related tasks even if allocating tasks
> are unexpectedly blocked for so long. Regarding premature OOM killer
> invocation, tracepoints which can accumulate samples in short interval
> would be useful. But regarding too late to report allocation stalls,
> this patch which can capture all tasks (for reporting overall situation)
> in longer interval and act as a trigger (for accumulating short interval
> samples) would be useful.

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Re: [PATCH v7] mm: Add memory allocation watchdog kernel thread. Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2017-03-09 12:50 +0100
  Re: [PATCH v7] mm: Add memory allocation watchdog kernel thread. Andrew Morton <akpm@linux-foundation.org> - 2017-03-09 23:40 +0100
    Re: [PATCH v7] mm: Add memory allocation watchdog kernel thread. Michal Hocko <mhocko@kernel.org> - 2017-03-10 11:50 +0100
      Re: [PATCH v7] mm: Add memory allocation watchdog kernel thread. Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2017-03-10 12:30 +0100
        Re: [PATCH v7] mm: Add memory allocation watchdog kernel thread. Brian Foster <bfoster@redhat.com> - 2017-03-10 15:00 +0100
        Re: [PATCH v7] mm: Add memory allocation watchdog kernel thread. Michal Hocko <mhocko@kernel.org> - 2017-03-10 16:30 +0100
          Re: [PATCH v7] mm: Add memory allocation watchdog kernel thread. Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2017-03-11 02:50 +0100
            Re: [PATCH v7] mm: Add memory allocation watchdog kernel thread. Michal Hocko <mhocko@kernel.org> - 2017-03-13 10:50 +0100
              Re: [PATCH v7] mm: Add memory allocation watchdog kernel thread. Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2017-03-13 14:50 +0100

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