Re: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL

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To: Barry Song <21cnbao@xxxxxxxxx>
Subject: Re: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL
From: Michal Hocko <mhocko@xxxxxxxx>
Date: Thu, 18 Jul 2024 10:32:49 +0200
Cc: akpm@xxxxxxxxxxxxxxxxxxxx, linux-mm@xxxxxxxxx, Barry Song <v-songbaohua@xxxxxxxx>, Uladzislau Rezki <urezki@xxxxxxxxx>, Christoph Hellwig <hch@xxxxxxxxxxxxx>, Lorenzo Stoakes <lstoakes@xxxxxxxxx>, Christoph Lameter <cl@xxxxxxxxx>, Pekka Enberg <penberg@xxxxxxxxxx>, David Rientjes <rientjes@xxxxxxxxxx>, Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>, Vlastimil Babka <vbabka@xxxxxxx>, Roman Gushchin <roman.gushchin@xxxxxxxxx>, Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
In-reply-to: <CAGsJ_4wzpSLbteULhnTrQa_p5ETjiCTRHfF9Ph34=WZiub3irA@mail.gmail.com>
References: <20240717230025.77361-1-21cnbao@gmail.com> <Zpi9JJGUih2_VAMF@tiehlicka> <CAGsJ_4x0Bak+H0zJNH4FKLqd-Dmm4HhT5S4CzsoUaNiDKHNTtA@mail.gmail.com> <ZpjD7PKBOOzZU0sp@tiehlicka> <CAGsJ_4w0dJyJhYLe4T908=fGUC54yHcNaCA22QBN8OSkpxTrqg@mail.gmail.com> <ZpjJpvu5xWlDx4gD@tiehlicka> <CAGsJ_4wzpSLbteULhnTrQa_p5ETjiCTRHfF9Ph34=WZiub3irA@mail.gmail.com>

On Thu 18-07-24 20:18:02, Barry Song wrote:
> So the purpose is making sure the semantics - NOFAIL means no failure
> and we don't need to check ret.  If we can't really succeed, it should throw
> a BUG to stop any potential exploits.

This would require to panic consistently on failure in all allocator
path that can bail out. E.g. page allocator on GFP_NOWAIT|GFP_NOFAIL
req. not sure how many more.
-- 
Michal Hocko
SUSE Labs

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- Re: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL
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References:
- [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL
  - From: Barry Song
- Re: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL
  - From: Michal Hocko
- Re: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL
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- Re: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL
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- Re: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL
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- Re: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL
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- Re: [PATCH RFC] mm: warn potential return NULL for kmalloc_array and kvmalloc_array with __GFP_NOFAIL
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