This is a note to let you know that I've just added the patch titled
mm: kmem: drop __GFP_NOFAIL when allocating objcg vectors
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-kmem-drop-__gfp_nofail-when-allocating-objcg-vectors.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 24948e3b7b12e0031a6edb4f49bbb9fb2ad1e4e9 Mon Sep 17 00:00:00 2001
From: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Date: Tue, 7 Nov 2023 09:18:02 -0800
Subject: mm: kmem: drop __GFP_NOFAIL when allocating objcg vectors
From: Roman Gushchin <roman.gushchin@xxxxxxxxx>
commit 24948e3b7b12e0031a6edb4f49bbb9fb2ad1e4e9 upstream.
Objcg vectors attached to slab pages to store slab object ownership
information are allocated using gfp flags for the original slab
allocation. Depending on slab page order and the size of slab objects,
objcg vector can take several pages.
If the original allocation was done with the __GFP_NOFAIL flag, it
triggered a warning in the page allocation code. Indeed, order > 1 pages
should not been allocated with the __GFP_NOFAIL flag.
Fix this by simply dropping the __GFP_NOFAIL flag when allocating the
objcg vector. It effectively allows to skip the accounting of a single
slab object under a heavy memory pressure.
An alternative would be to implement the mechanism to fallback to order-0
allocations for accounting metadata, which is also not perfect because it
will increase performance penalty and memory footprint of the kernel
memory accounting under memory pressure.
Link: https://lkml.kernel.org/r/ZUp8ZFGxwmCx4ZFr@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Reported-by: Christoph Lameter <cl@xxxxxxxxx>
Closes: https://lkml.kernel.org/r/6b42243e-f197-600a-5d22-56bd728a5ad8@xxxxxxxxxx
Acked-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2822,7 +2822,8 @@ retry:
* Moreover, it should not come from DMA buffer and is not readily
* reclaimable. So those GFP bits should be masked off.
*/
-#define OBJCGS_CLEAR_MASK (__GFP_DMA | __GFP_RECLAIMABLE | __GFP_ACCOUNT)
+#define OBJCGS_CLEAR_MASK (__GFP_DMA | __GFP_RECLAIMABLE | \
+ __GFP_ACCOUNT | __GFP_NOFAIL)
int memcg_alloc_page_obj_cgroups(struct page *page, struct kmem_cache *s,
gfp_t gfp, bool new_page)
Patches currently in stable-queue which might be from roman.gushchin@xxxxxxxxx are
queue-5.15/mm-kmem-drop-__gfp_nofail-when-allocating-objcg-vectors.patch
