linux-kernel - Re: [PATCH v2] mm: fix unexpected changes to {failslab|fail_page

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Message-ID: <CAC5umygzc=H-9dCa_pLoqodS4Qz90OVmQkrvFOCPv27514tP3A@mail.gmail.com>
Date:   Wed, 9 Nov 2022 02:36:32 +0900
From:   Akinobu Mita <akinobu.mita@...il.com>
To:     Qi Zheng <zhengqi.arch@...edance.com>
Cc:     dvyukov@...gle.com, jgg@...dia.com, willy@...radead.org,
        akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH v2] mm: fix unexpected changes to {failslab|fail_page_alloc}.attr

2022年11月8日(火) 12:52 Qi Zheng <zhengqi.arch@...edance.com>:
>
> When we specify __GFP_NOWARN, we only expect that no warnings
> will be issued for current caller. But in the __should_failslab()
> and __should_fail_alloc_page(), the local GFP flags alter the
> global {failslab|fail_page_alloc}.attr, which is persistent and
> shared by all tasks. This is not what we expected, let's fix it.
>
> Cc: stable@...r.kernel.org
> Fixes: 3f913fc5f974 ("mm: fix missing handler for __GFP_NOWARN")
> Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
> Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
> ---
>  v1: https://lore.kernel.org/lkml/20221107033109.59709-1-zhengqi.arch@bytedance.com/
>
>  Changelog in v1 -> v2:
>   - add comment for __should_failslab() and __should_fail_alloc_page()
>     (suggested by Jason)

Looks good.

Reviewed-by: Akinobu Mita <akinobu.mita@...il.com>