The patch titled
Subject: mm: kmem: drop __GFP_NOFAIL when allocating objcg vectors
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
cgroups-warning-for-metadata-allocation-with-gfp_nofail-was-re-folio_alloc_buffers-doing-allocations-order-1-with-gfp_nofail.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/cgroups-warning-for-metadata-allocation-with-gfp_nofail-was-re-folio_alloc_buffers-doing-allocations-order-1-with-gfp_nofail.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Subject: mm: kmem: drop __GFP_NOFAIL when allocating objcg vectors
Date: Tue, 7 Nov 2023 09:18:02 -0800
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>
---
mm/memcontrol.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/memcontrol.c~cgroups-warning-for-metadata-allocation-with-gfp_nofail-was-re-folio_alloc_buffers-doing-allocations-order-1-with-gfp_nofail
+++ a/mm/memcontrol.c
@@ -2936,7 +2936,8 @@ void mem_cgroup_commit_charge(struct fol
* 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)
/*
* mod_objcg_mlstate() may be called with irq enabled, so
_
Patches currently in -mm which might be from roman.gushchin@xxxxxxxxx are
cgroups-warning-for-metadata-allocation-with-gfp_nofail-was-re-folio_alloc_buffers-doing-allocations-order-1-with-gfp_nofail.patch
