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Date: Tue, 29 Sep 2015 15:41:52 -0700 (PDT)
From: David Rientjes <rientjes@google.com>
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To: Oleg Nesterov <oleg@redhat.com>
cc: Andrew Morton <akpm@linux-foundation.org>,
        Kyle Walker <kwalker@redhat.com>, Michal Hocko <mhocko@kernel.org>,
        Stanislav Kozina <skozina@redhat.com>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH -mm 3/3] mm/oom_kill: fix the wrong task->mm == mm checks
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On Tue, 29 Sep 2015, Oleg Nesterov wrote:

> Both "child->mm == mm" and "p->mm != mm" checks in oom_kill_process()
> are wrong. ->mm can be if task is the exited group leader. This means
> in particular that "kill sharing same memory" loop can miss a process
> with a zombie leader which uses the same ->mm.
> 
> Note: the process_has_mm(child, p->mm) check is still not 100% correct,
> p->mm can be NULL too. This is minor, but probably deserves a fix or a
> comment anyway.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Acked-by: David Rientjes <rientjes@google.com>

I like this and I don't want to hold up a fix for a personal preference, 
but I find process_has_mm() to simply imply the process has a non-NULL mm.  
Maybe process_shares_mm()?  Something to consider.