Re: [PATCH] mm: ensure alloc_flags in slow path are initialized

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From	Arnd Bergmann <arnd@arndb.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH] mm: ensure alloc_flags in slow path are initialized
Date	Mon, 23 Jan 2017 17:10:02 +0100
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On Mon, Jan 23, 2017 at 1:55 PM, Vlastimil Babka <vbabka@suse.cz> wrote:
> On 01/23/2017 01:16 PM, Arnd Bergmann wrote:

>> To be honest, I can't figure that out either, maybe it is or
>> maybe not,
>
>
> Seems the report is correct and not false positive, in scenario when we goto
> nopage before the assignment, and then goto retry because of __GFP_NOFAIL.

Ok, thanks for checking!

>> but moving the existing initialization up a little
>> higher looks safe and makes it obvious to both me and gcc that
>> the initialization comes before the first use.
>>
>> Fixes: 74eaa4a97e8e ("mm: consolidate GFP_NOFAIL checks in the allocator
>> slowpath")
>
>
> That's a non-stable -next commit ID for mmotm patch:
> mm-consolidate-gfp_nofail-checks-in-the-allocator-slowpath.patch
>
> The patch itself was OK, the problem only comes from integration with
> another mmotm patch (also independently OK):
> mm-page_alloc-fix-premature-oom-when-racing-with-cpuset-mems-update.patch
>
> By their ordering in mmotm, it would work to treat this as a fix for the
> GFP_NOFAIL patch, possibly merged into it.

Ok. I only tracked down which commit introduced the warning, which was
the one above.

    Arnd

Thread

[PATCH] mm: ensure alloc_flags in slow path are initialized Arnd Bergmann <arnd@arndb.de> - 2017-01-23 13:20 +0100
  Re: [PATCH] mm: ensure alloc_flags in slow path are initialized Vlastimil Babka <vbabka@suse.cz> - 2017-01-23 14:00 +0100
    Re: [PATCH] mm: ensure alloc_flags in slow path are initialized Arnd Bergmann <arnd@arndb.de> - 2017-01-23 17:10 +0100
  Re: [PATCH] mm: ensure alloc_flags in slow path are initialized David Rientjes <rientjes@google.com> - 2017-01-24 00:00 +0100
  Re: [PATCH] mm: ensure alloc_flags in slow path are initialized Andrew Morton <akpm@linux-foundation.org> - 2017-01-24 01:00 +0100
    Re: [PATCH] mm: ensure alloc_flags in slow path are initialized Vlastimil Babka <vbabka@suse.cz> - 2017-01-24 10:20 +0100

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