linux-kernel - Re: [PATCH] slub: let need_slab_obj_exts() return false if SLAB_NO_OBJ

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Message-ID: <e924ce7e-29c8-4853-b1c2-3495b8cf8427@suse.cz>
Date: Fri, 6 Feb 2026 11:03:08 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Harry Yoo <harry.yoo@...cle.com>
Cc: Hao Li <hao.li@...ux.dev>, akpm@...ux-foundation.org, cl@...two.org,
 rientjes@...gle.com, roman.gushchin@...ux.dev, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] slub: let need_slab_obj_exts() return false if
 SLAB_NO_OBJ_EXT is set

On 2/6/26 11:01, Harry Yoo wrote:
> On Fri, Feb 06, 2026 at 10:40:54AM +0100, Vlastimil Babka wrote:
>> On 2/6/26 01:53, Harry Yoo wrote:
>> > On Thu, Feb 05, 2026 at 08:07:23PM +0800, Hao Li wrote:
>> >> SLAB_NO_OBJ_EXT is set for boot caches, but need_slab_obj_exts() doesn't
>> >> check this flag. We should return false unconditionally when
>> >> SLAB_NO_OBJ_EXT is set.
>> >> 
>> >> Signed-off-by: Hao Li <hao.li@...ux.dev>
>> >> ---
>> > 
>> > Looks reasonable to me,
>> > Acked-by: Harry Yoo <harry.yoo@...cle.com>
>> 
>> Thanks, added to slab/for-7.0/obj_metadata
>> I think it doesn't change anything at the moment?
> 
> ...unless you enable memory allocation profiling :)

If I do, would kmem_cache or kmem_cache_node caches gotten obj_exts in
leftover space?

>> But a correct thing to do.
>