linux-kernel - Re: [patch] mm, oom: stop reclaiming if GFP

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <fed6a727-1005-cb12-0ad0-4d9a6bb06564@I-love.SAKURA.ne.jp>
Date:   Mon, 27 Apr 2020 14:03:15 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     David Rientjes <rientjes@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [patch] mm, oom: stop reclaiming if GFP_ATOMIC will start failing
 soon

On 2020/04/27 12:12, David Rientjes wrote:
> Tetsuo: the specific allocation that triggers a page allocation failure is 
> not interesting; we have tens of thousands of examples.  Each example is 
> simply the unlucky last GFP_ATOMIC allocation that fails; the interesting 
> point is the amount of free memory.  In other words, when free memory is 
> below ALLOC_HIGH watermarks, we assume that we have depleted memory 
> reserves *faster* than when user allocations started to fail.  In the 
> interest of userspace being responsive, we should oom kill here.

My interest is, which function (and which process if process context) is [ab]using
GFP_ATOMIC (or __GFP_MEMALLOC) allocations enough to hit memory allocation failure.
GFP_NOWAIT (or __GFP_NOMEMALLOC) could be used if that allocation can't sleep and
can't shortly recover free memory.