Commit 73293c2f authored by Joonsoo Kim's avatar Joonsoo Kim Committed by Pekka Enberg
Browse files

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: default avatarAndi Kleen <ak@linux.intel.com>
Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: default avatarPekka Enberg <penberg@iki.fi>
parent 6e466452

mm/slab.c

+5 −3
Original line number Original line Diff line number Diff line
@@ -930,7 +930,8 @@ static void *__ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac, 
{

{

	if (unlikely(pfmemalloc_active)) {

	if (unlikely(pfmemalloc_active)) {

		/* Some pfmemalloc slabs exist, check if this is one */

		/* 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))

		if (PageSlabPfmemalloc(page))

			set_obj_pfmemalloc(&objp);

			set_obj_pfmemalloc(&objp);

	}

	}
@@ -1776,7 +1777,7 @@ static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid) 
		__SetPageSlab(page + i);

		__SetPageSlab(page + i);





		if (page->pfmemalloc)

		if (page->pfmemalloc)

			SetPageSlabPfmemalloc(page + i);

			SetPageSlabPfmemalloc(page);

	}

	}

	memcg_bind_pages(cachep, cachep->gfporder);

	memcg_bind_pages(cachep, cachep->gfporder);
@@ -1809,9 +1810,10 @@ static void kmem_freepages(struct kmem_cache *cachep, void *addr) 
	else

	else

		sub_zone_page_state(page_zone(page),

		sub_zone_page_state(page_zone(page),

				NR_SLAB_UNRECLAIMABLE, nr_freed);

				NR_SLAB_UNRECLAIMABLE, nr_freed);



	__ClearPageSlabPfmemalloc(page);

	while (i--) {

	while (i--) {

		BUG_ON(!PageSlab(page));

		BUG_ON(!PageSlab(page));

		__ClearPageSlabPfmemalloc(page);

		__ClearPageSlab(page);

		__ClearPageSlab(page);

		page++;

		page++;

	}

	}

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