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slab: correct pfmemalloc check 

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).

Acked-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Pekka Enberg <penberg@iki.fi>
This commit is contained in:
Joonsoo Kim 2013-10-24 10:07:37 +09:00 committed by Pekka Enberg
parent 6e4664525b
commit 73293c2f90
1 changed files with 5 additions and 3 deletions
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8
mm/slab.c
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@ -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);
}
@ -1776,7 +1777,7 @@ 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);
@ -1809,9 +1810,10 @@ 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++;
}