The patch titled
Subject: slab: do ClearSlabPfmemalloc() for all pages of slab
has been added to the -mm tree. Its filename is
slab-do-clearslabpfmemalloc-for-all-pages-of-slab.patch
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------------------------------------------------------
From: Mel Gorman <mgorman@xxxxxxx>
Subject: slab: do ClearSlabPfmemalloc() for all pages of slab
Right now, we call ClearSlabPfmemalloc() for first page of slab when we
clear SlabPfmemalloc flag. This is fine for most swap-over-network use
cases as it is expected that order-0 pages are in use. Unfortunately it
is possible that that __ac_put_obj() checks SlabPfmemalloc on a tail page
and while this is harmless, it is sloppy. This patch ensures that the
head page is always used.
This problem was originally identified by Joonsoo Kim.
[js1304@xxxxxxxxx: Original implementation and problem identification]
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Cc: David Miller <davem@xxxxxxxxxxxxx>
Cc: Chuck Lever <chuck.lever@xxxxxxxxxx>
Cc: Joonsoo Kim <js1304@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slab.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff -puN mm/slab.c~slab-do-clearslabpfmemalloc-for-all-pages-of-slab mm/slab.c
--- a/mm/slab.c~slab-do-clearslabpfmemalloc-for-all-pages-of-slab
+++ a/mm/slab.c
@@ -1000,7 +1000,7 @@ static void *__ac_get_obj(struct kmem_ca
l3 = cachep->nodelists[numa_mem_id()];
if (!list_empty(&l3->slabs_free) && force_refill) {
struct slab *slabp = virt_to_slab(objp);
- ClearPageSlabPfmemalloc(virt_to_page(slabp->s_mem));
+ ClearPageSlabPfmemalloc(virt_to_head_page(slabp->s_mem));
clear_obj_pfmemalloc(&objp);
recheck_pfmemalloc_active(cachep, ac);
return objp;
@@ -1032,7 +1032,7 @@ static void *__ac_put_obj(struct kmem_ca
{
if (unlikely(pfmemalloc_active)) {
/* Some pfmemalloc slabs exist, check if this is one */
- struct page *page = virt_to_page(objp);
+ struct page *page = virt_to_head_page(objp);
if (PageSlabPfmemalloc(page))
set_obj_pfmemalloc(&objp);
}
_
Patches currently in -mm which might be from mgorman@xxxxxxx are
origin.patch
slab-do-clearslabpfmemalloc-for-all-pages-of-slab.patch
slab-fix-starting-index-for-finding-another-object.patch
slub-consider-pfmemalloc_match-in-get_partial_node.patch
include-net-sockh-squelch-compiler-warning-in-sk_rmem_schedule.patch
mm-remove-__gfp_no_kswapd.patch
mm-compaction-update-comment-in-try_to_compact_pages.patch
mm-vmscan-scale-number-of-pages-reclaimed-by-reclaim-compaction-based-on-failures.patch
mm-compaction-capture-a-suitable-high-order-page-immediately-when-it-is-made-available.patch
revert-mm-mempolicy-let-vma_merge-and-vma_split-handle-vma-vm_policy-linkages.patch
mempolicy-remove-mempolicy-sharing.patch
mempolicy-fix-a-race-in-shared_policy_replace.patch
mempolicy-fix-refcount-leak-in-mpol_set_shared_policy.patch
mempolicy-fix-a-memory-corruption-by-refcount-imbalance-in-alloc_pages_vma.patch
mempolicy-fix-a-memory-corruption-by-refcount-imbalance-in-alloc_pages_vma-v2.patch
--
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