Re: [PATCH v2] mm: fix unexpected changes to {failslab|fail_page_alloc}.attr

From: Qi Zheng
Date: Sun Nov 13 2022 - 23:00:03 EST




On 2022/11/9 01:36, Akinobu Mita wrote:
2022年11月8日(火) 12:52 Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>:

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@xxxxxxxxxxxxxxx
Fixes: 3f913fc5f974 ("mm: fix missing handler for __GFP_NOWARN")
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
---
v1: https://lore.kernel.org/lkml/20221107033109.59709-1-zhengqi.arch@xxxxxxxxxxxxx/

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@xxxxxxxxx>

Thanks. And hi Andrew, seems no action left for me, can this patch
be applied to mm-unstable tree for testing? :)

--
Thanks,
Qi