From: Shengming Hu kmem_cache_return_sheaf() may refill a partially consumed sheaf before placing it in the barn. Without an explicit restriction, this refill may draw objects from pfmemalloc slabs and consume emergency reserves. Add __GFP_NOMEMALLOC so that returned sheaves are refilled only from non-pfmemalloc slabs. Also add __GFP_NOWARN, as suggested by Hao Li, because this refill is a best-effort attempt and failure is acceptable. If the refill fails, flush and free the sheaf instead. Fixes: 3c1ea5c5019f ("slab: sheaf prefilling for guaranteed allocations") Cc: stable@vger.kernel.org Signed-off-by: Shengming Hu --- Changes in v3: - Replace “normal memory” with the more precise “non-pfmemalloc slabs”, and add Fixes: and Cc: stable@vger.kernel.org, as suggested by Harry. - Link to v2: https://lore.kernel.org/all/20260720211127124sYtTNbvsxCXN9_pDh-pwt@zte.com.cn/ Changes in v2: - Add __GFP_NOWARN as suggested by Hao. - Link to v1: https://lore.kernel.org/all/20260719113701797vZ3R8NxiqYt8dEfeUxtON@zte.com.cn/ --- mm/slub.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index 53b4976d3831..357b7522c817 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -5123,7 +5123,7 @@ void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp, * simply flush and free it. */ if (!barn || data_race(barn->nr_full) >= MAX_FULL_SHEAVES || - refill_sheaf(s, sheaf, gfp)) { + refill_sheaf(s, sheaf, gfp | __GFP_NOMEMALLOC | __GFP_NOWARN)) { sheaf_flush_unused(s, sheaf); free_empty_sheaf(s, sheaf); return; -- 2.25.1