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Date:   Wed, 25 Jul 2018 08:13:55 +0200
From:   Michal Hocko <mhocko@kernel.org>
To:     David Rientjes <rientjes@google.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>, linux-mm@kvack.org,
        "David (ChunMing) Zhou" <David1.Zhou@amd.com>,
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        Alex Deucher <alexander.deucher@amd.com>,
        David Airlie <airlied@linux.ie>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        Doug Ledford <dledford@redhat.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Mike Marciniszyn <mike.marciniszyn@intel.com>,
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        Sudeep Dutt <sudeep.dutt@intel.com>,
        Ashutosh Dixit <ashutosh.dixit@intel.com>,
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        Juergen Gross <jgross@suse.com>,
        =?iso-8859-1?B?Suly9G1l?= Glisse <jglisse@redhat.com>,
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        Felix Kuehling <felix.kuehling@amd.com>, kvm@vger.kernel.org,
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        Christian =?iso-8859-1?Q?K=F6nig?= <christian.koenig@amd.com>,
        Leon Romanovsky <leonro@mellanox.com>
Subject: Re: [PATCH] mm, oom: distinguish blockable mode for mmu notifiers
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On Tue 24-07-18 14:07:49, David Rientjes wrote:
[...]
> mm/oom_kill.c: clean up oom_reap_task_mm() fix
> 
> indicate reaping has been partially skipped so we can expect future skips 
> or another start before finish.

But we are not skipping. This is essentially the same case as mmap_sem
trylock fail. Maybe we can add a bool parameter to trace_finish_task_reaping
to denote partial success?

> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
>  mm/oom_kill.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -569,10 +569,12 @@ static bool oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm)
>  
>  	trace_start_task_reaping(tsk->pid);
>  
> -	/* failed to reap part of the address space. Try again later */
>  	ret = __oom_reap_task_mm(mm);
> -	if (!ret)
> +	if (!ret) {
> +		/* Failed to reap part of the address space. Try again later */
> +		trace_skip_task_reaping(tsk->pid);
>  		goto out_finish;
> +	}
>  
>  	pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
>  			task_pid_nr(tsk), tsk->comm,

-- 
Michal Hocko
SUSE Labs