On 7/21/26 9:45 AM, hu.shengming@zte.com.cn wrote: > 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 > --- Looks good to me, Reviewed-by: Harry Yoo (Oracle) > 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; -- Cheers, Harry / Hyeonggon