Re: [PATCH] mm/slab: improve kmem_cache_alloc_bulk

[Harry Yoo <harry@kernel.org>]

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On 5/29/26 10:50 PM, Christoph Hellwig wrote:
> On Fri, May 29, 2026 at 01:54:48PM +0200, Vlastimil Babka (SUSE) wrote:
>> Thanks, I applied it to slab/for-7.2/alloc_bulk and merged to slab/for-next
>> (it's still yankable in case of issues)
>>
>> Did some fixups below (the comment was stale prior to the patch; restored
>> unlikely(), simplified one line).
>>
>> A test merge into yesterday's -next found a conflict in drivers/gpu/drm/
>> panthor/panthor_mmu.c. Commit 1013bf53650e ("drm/panthor: Split
>> panthor_vm_prepare_map_op_ctx() to prepare for reclaim") moved the changed
>> codeto a new function panthor_vm_op_ctx_prealloc_pts().
>> But it's solvable so no need for a complicated coordination I think.
> 
> Ok, thanks.  The two Sashiko complains also look like they had merrits,
> but I won't get to looking into them until Monday.
The review:
https://sashiko.dev/#/patchset/20260528093437.2519248-2-hch%40lst.de

So there is a user who might call kmem_cache_alloc_bulk() with size = 0
(although the comment says @size must be larger than 0!) and
kmem_cache_alloc_bulk() returning 0 was considered a success in that case.

Either fixing kmem_cache_alloc_bulk() (and the comment) or fixing the
user sounds fine to me.

And yeah freeing an object via kfree() allocated via kvmalloc is a bug...

-- 
Cheers,
Harry / Hyeonggon


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