linux-kernel - Re: [RFC PATCH 2/2] mm, oom: do not trigger out_of

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Date:   Mon, 22 May 2017 11:31:11 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc:     akpm@...ux-foundation.org, hannes@...xchg.org, guro@...com,
        vdavydov.dev@...il.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 2/2] mm, oom: do not trigger out_of_memory from the
 #PF

On Sat 20-05-17 08:43:29, Tetsuo Handa wrote:
> Michal Hocko wrote:
[...]
> > Why would looping inside an allocator with a restricted context be any
> > better than retrying the whole thing?
> 
> I'm not suggesting you to loop inside an allocator nor retry the whole thing.
> I'm suggesting you to avoid returning VM_FAULT_OOM by making allocations succeed
> (by e.g. calling oom_kill_process()) regardless of restricted context if you
> want to remove out_of_memory() from pagefault_out_of_memory(), for situation
> will not improve until memory is allocated (e.g. somebody else calls
> oom_kill_process() via a __GFP_FS allocation request).

And again for the hundred and so many times I will only repeat that
triggering OOM from those restricted contexts is just too dangerous
without other changes.

-- 
Michal Hocko
SUSE Labs