Re: [PATCH v2 05/16] mm/slab: introduce alloc_flags and SLAB_ALLOC_TRYLOCK

[Hao Li]

On Wed, Jun 10, 2026 at 05:40:07PM +0200, Vlastimil Babka (SUSE) wrote:
> Similarly to the page allocators, introduce slab-allocator specific
> alloc flags that internally control allocation behavior in addition to
> gfp_flags, without occupying the limited gfp flags space.
> 
> Introduce the first flag SLAB_ALLOC_TRYLOCK that behaves similarly to
> page allocator's ALLOC_TRYLOCK and will be used to reimplement
> kmalloc_nolock()'s "!allow_spin" behavior. That currently relies on
> gfpflags_allow_spinning() and thus the lack of both __GFP_RECLAIM flags,
> importantly __GFP_KSWAPD_RECLAIM. This can give false-positive results
> e.g. in early boot with a restricted gfp_allowed_mask.
> 
> Also introduce alloc_flags_allow_spinning() to replace the usage of
> gfpflags_allow_spinning().
> 
> Start using alloc_flags and the new check first in alloc_from_pcs() and
> __pcs_replace_empty_main(). This means some slab allocations that were
> falsely treated as kmalloc_nolock() due to their gfp flags will now have
> higher chances of succeed, and this will further increase with followup
> changes.
> 
> Remove a WARN_ON_ONCE() from refill_objects() as it's now legitimate to
> reach it from a slab allocation that's not _nolock() and yet lacks
> __GFP_KSWAPD_RECLAIM for other reasons.
> 
> Signed-off-by: Vlastimil Babka (SUSE) <vbabka@xxxxxxxxxx>
> ---

Reviewed-by: Hao Li <hao.li@xxxxxxxxx>

-- 
Thanks,
Hao