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Date: Tue, 3 Apr 2018 13:16:40 +0200
From: Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH] mm: Check for SIGKILL inside dup_mmap() loop.
Message-ID: <20180403111640.GN5501@dhcp22.suse.cz>
References: <1522322870-4335-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp>
 <20180329143003.c52ada618be599c5358e8ca2@linux-foundation.org>
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To: Andrew Morton <akpm@linux-foundation.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Alexander Viro <viro@zeniv.linux.org.uk>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Rik van Riel <riel@redhat.com>

On Thu 29-03-18 14:30:03, Andrew Morton wrote:
[...]
> Dumb question: if a thread has been oom-killed and then tries to
> allocate memory, should the page allocator just fail the allocation
> attempt?  I suppose there are all sorts of reasons why not :(

We give those tasks access to memory reserves to move on (see
oom_reserves_allowed) and fail allocation if reserves do not help

	if (tsk_is_oom_victim(current) &&
	    (alloc_flags == ALLOC_OOM ||
	     (gfp_mask & __GFP_NOMEMALLOC)))
		goto nopage;
So we...

> In which case, yes, setting a new
> PF_MEMALLOC_MAY_FAIL_IF_I_WAS_OOMKILLED around such code might be a
> tidy enough solution.  It would be a bit sad to add another test in the
> hot path (should_fail_alloc_page()?), but geeze we do a lot of junk
> already.

... do not need this.
-- 
Michal Hocko
SUSE Labs