Commit 021ca6b6 authored by Harry Yoo's avatar Harry Yoo Committed by Vlastimil Babka (SUSE)
Browse files

mm/slab: pass __GFP_NOWARN to refill_sheaf() if fallback is available 



When refill_sheaf() is called, failing to refill the sheaf doesn't
necessarily mean the allocation will fail because a fallback path
might be available and serve the allocation request.

Suppress spurious warnings by passing __GFP_NOWARN along with
__GFP_NOMEMALLOC whenever a fallback path is available.

When the caller is alloc_full_sheaf() or __pcs_replace_empty_main(),
the kernel always falls back to the slowpath (__slab_alloc_node()).
For __prefill_sheaf_pfmemalloc(), the fallback path is available
only when gfp_pfmemalloc_allowed() returns true.

Reported-and-tested-by: default avatarChris Bainbridge <chris.bainbridge@gmail.com>
Closes: https://lore.kernel.org/linux-mm/aZt2-oS9lkmwT7Ch@debian.local
Fixes: 1ce20c28 ("slab: handle pfmemalloc slabs properly with sheaves")
Link: https://lore.kernel.org/linux-mm/aZwSreGj9-HHdD-j@hyeyoo


Signed-off-by: default avatarHarry Yoo <harry.yoo@oracle.com>
Link: https://patch.msgid.link/20260223133322.16705-1-harry.yoo@oracle.com


Tested-by: default avatarMikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Signed-off-by: default avatarVlastimil Babka (SUSE) <vbabka@kernel.org>
parent 6de23f81

mm/slub.c

+9 −4
Original line number Diff line number Diff line
@@ -2822,7 +2822,7 @@ static struct slab_sheaf *alloc_full_sheaf(struct kmem_cache *s, gfp_t gfp) 
	if (!sheaf)

		return NULL;



	if (refill_sheaf(s, sheaf, gfp | __GFP_NOMEMALLOC)) {

	if (refill_sheaf(s, sheaf, gfp | __GFP_NOMEMALLOC | __GFP_NOWARN)) {

		free_empty_sheaf(s, sheaf);

		return NULL;

	}
@@ -4575,7 +4575,7 @@ __pcs_replace_empty_main(struct kmem_cache *s, struct slub_percpu_sheaves *pcs, 
		return NULL;



	if (empty) {

		if (!refill_sheaf(s, empty, gfp | __GFP_NOMEMALLOC)) {

		if (!refill_sheaf(s, empty, gfp | __GFP_NOMEMALLOC | __GFP_NOWARN)) {

			full = empty;

		} else {

			/*
@@ -4890,9 +4890,14 @@ EXPORT_SYMBOL(kmem_cache_alloc_node_noprof); 
static int __prefill_sheaf_pfmemalloc(struct kmem_cache *s,

				      struct slab_sheaf *sheaf, gfp_t gfp)

{

	int ret = 0;

	gfp_t gfp_nomemalloc;

	int ret;



	gfp_nomemalloc = gfp | __GFP_NOMEMALLOC;

	if (gfp_pfmemalloc_allowed(gfp))

		gfp_nomemalloc |= __GFP_NOWARN;



	ret = refill_sheaf(s, sheaf, gfp | __GFP_NOMEMALLOC);

	ret = refill_sheaf(s, sheaf, gfp_nomemalloc);



	if (likely(!ret || !gfp_pfmemalloc_allowed(gfp)))

		return ret;