We checked pfmemalloc by slab unit, not page unit. You can see this
in is_slab_pfmemalloc(). So other pages don't need to be set/cleared
pfmemalloc.
And, therefore we should check pfmemalloc in page flag of first page,
but current implementation don't do that. virt_to_head_page(obj) just
return 'struct page' of that object, not one of first page, since the SLAB
don't use __GFP_COMP when CONFIG_MMU. To get 'struct page' of first page,
we first get a slab and try to get it via virt_to_head_page(slab->s_mem).
Cc: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
diff --git a/mm/slab.c b/mm/slab.c
index 8ccd296..d9eae39 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -930,7 +930,8 @@ static void *__ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
{
if (unlikely(pfmemalloc_active)) {
/* Some pfmemalloc slabs exist, check if this is one */
- struct page *page = virt_to_head_page(objp);
+ struct slab *slabp = virt_to_slab(objp);
+ struct page *page = virt_to_head_page(slabp->s_mem);
if (PageSlabPfmemalloc(page))
set_obj_pfmemalloc(&objp);
}
@@ -1770,7 +1771,7 @@ static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
__SetPageSlab(page + i);
if (page->pfmemalloc)
- SetPageSlabPfmemalloc(page + i);
+ SetPageSlabPfmemalloc(page);
}
memcg_bind_pages(cachep, cachep->gfporder);
@@ -1803,9 +1804,10 @@ static void kmem_freepages(struct kmem_cache *cachep, void *addr)
else
sub_zone_page_state(page_zone(page),
NR_SLAB_UNRECLAIMABLE, nr_freed);
+
+ __ClearPageSlabPfmemalloc(page);
while (i--) {
BUG_ON(!PageSlab(page));
- __ClearPageSlabPfmemalloc(page);
__ClearPageSlab(page);
page++;
}
--
1.7.9.5
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