Re: [PATCH v5] mm/slub: use empty sheaf helpers for oversized sheaves

[Hao Li <hao.li@linux.dev>]

On Thu, May 28, 2026 at 07:35:37PM +0800, hu.shengming@zte.com.cn wrote:
> From: Shengming Hu <hu.shengming@zte.com.cn>
> 
> Oversized prefilled sheaves are allocated separately because their
> capacity can be larger than the cache's regular sheaf capacity. After
> they are flushed, however, they are empty sheaves as well, and should be
> released through the same empty-sheaf helper.
> 
> Allocate oversized prefilled sheaves with __alloc_empty_sheaf() and free
> them with free_empty_sheaf() after a failed prefill or after they are
> returned and flushed. This keeps the oversized and pfmemalloc return paths
> consistent, including the SLAB_KMALLOC-specific __GFP_NO_OBJ_EXT and
> mark_obj_codetag_empty() handling.
> 
> Keep the caller-GFP filtering in alloc_empty_sheaf() instead of
> __alloc_empty_sheaf(). In particular, do not clear OBJCGS_CLEAR_MASK in
> the raw helper, so the oversized prefill path does not unexpectedly drop
> caller-provided flags such as __GFP_NOFAIL. The SLAB_KMALLOC-specific
> addition of __GFP_NO_OBJ_EXT remains in __alloc_empty_sheaf(), matching
> the free_empty_sheaf() assumption.
> 
> Since oversized sheaves are now allocated and freed through the empty
> sheaf helpers, SHEAF_ALLOC and SHEAF_FREE also account for oversized
> sheaves. Update the stat comments accordingly.
> 
> Keep the capacity initialization in the oversized prefill path, since
> capacity is currently only used for prefilled sheaves
> 
> Signed-off-by: Shengming Hu <hu.shengming@zte.com.cn>

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

-- 
Thanks,
Hao