5.10-stable review patch. If anyone has any objections, please let me know.
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From: Roman Gushchin roman.gushchin@linux.dev
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@P9FQF9L96D.corp.robot.car Signed-off-by: Roman Gushchin roman.gushchin@linux.dev Reported-by: Christoph Lameter cl@linux.com Closes: https://lkml.kernel.org/r/6b42243e-f197-600a-5d22-56bd728a5ad8@gentwo.org Acked-by: Shakeel Butt shakeelb@google.com Cc: Matthew Wilcox willy@infradead.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/memcontrol.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2892,7 +2892,8 @@ static void commit_charge(struct page *p * 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)