linux-kernel - Re: [PATCH v2 for v5.9] mm/page_alloc: handle a missing case for memalloc_nocma

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]

Date:   Tue, 29 Sep 2020 15:46:02 +0900
From:   Joonsoo Kim <js1304@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Michal Hocko <mhocko@...nel.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        Mel Gorman <mgorman@...hsingularity.net>, kernel-team@....com,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v2 for v5.9] mm/page_alloc: handle a missing case for
 memalloc_nocma_{save/restore} APIs

2020년 9월 29일 (화) 오후 1:50, Andrew Morton <akpm@...ux-foundation.org>님이 작성:
>
> On Tue, 29 Sep 2020 10:28:05 +0900 Joonsoo Kim <js1304@...il.com> wrote:
>
> > > What about manually emptying the pcplists beforehand?
> >
> > It also increases the probability. schedule() or interrupt after emptying but
> > before the allocation could invalidate the effect.
>
> Keep local interrupts disabled across the pcp drain and the allocation
> attempt.

As said before, it's an allocation context API and actual allocation
happens later.
Doing such things there is not an easy job.

> > > Or byassing the pcplists for this caller and calling __rmqueue() directly?
> >
> > What this patch does is this one.
>
> I meant via a different function rather than by adding overhead to the
> existing commonly-used function.

Got it. One idea could be disabling/enabling pcp list on these APIs but
it's overhead would not be appropriate on these APIs. I don't have
another idea that doesn't touch the allocation path.

Thanks.