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Commit e767e056 authored by Daisuke Nishimura's avatar Daisuke Nishimura Committed by Linus Torvalds
Browse files

memcg: fix deadlock between lock_page_cgroup and mapping tree_lock 



mapping->tree_lock can be acquired from interrupt context.  Then,
following dead lock can occur.

Assume "A" as a page.

 CPU0:
       lock_page_cgroup(A)
		interrupted
			-> take mapping->tree_lock.
 CPU1:
       take mapping->tree_lock
		-> lock_page_cgroup(A)

This patch tries to fix above deadlock by moving memcg's hook to out of
mapping->tree_lock.  charge/uncharge of pagecache/swapcache is protected
by page lock, not tree_lock.

After this patch, lock_page_cgroup() is not called under mapping->tree_lock.

Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: default avatarDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent bd6daba9

include/linux/swap.h

+5 −0
Original line number Diff line number Diff line
@@ -437,6 +437,11 @@ static inline int mem_cgroup_cache_charge_swapin(struct page *page, 
	return 0;

}



static inline void

mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)

{

}



#endif /* CONFIG_SWAP */

#endif /* __KERNEL__*/

#endif /* _LINUX_SWAP_H */

mm/filemap.c

+3 −3
Original line number Diff line number Diff line
@@ -121,7 +121,6 @@ void __remove_from_page_cache(struct page *page) 
	mapping->nrpages--;

	__dec_zone_page_state(page, NR_FILE_PAGES);

	BUG_ON(page_mapped(page));

	mem_cgroup_uncharge_cache_page(page);



	/*

	 * Some filesystems seem to re-dirty the page even after
@@ -145,6 +144,7 @@ void remove_from_page_cache(struct page *page) 
	spin_lock_irq(&mapping->tree_lock);

	__remove_from_page_cache(page);

	spin_unlock_irq(&mapping->tree_lock);

	mem_cgroup_uncharge_cache_page(page);

}



static int sync_page(void *word)
@@ -476,13 +476,13 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping, 
		if (likely(!error)) {

			mapping->nrpages++;

			__inc_zone_page_state(page, NR_FILE_PAGES);

			spin_unlock_irq(&mapping->tree_lock);

		} else {

			page->mapping = NULL;

			spin_unlock_irq(&mapping->tree_lock);

			mem_cgroup_uncharge_cache_page(page);

			page_cache_release(page);

		}



		spin_unlock_irq(&mapping->tree_lock);

		radix_tree_preload_end();

	} else

		mem_cgroup_uncharge_cache_page(page);

mm/memcontrol.c

+3 −1
Original line number Diff line number Diff line
@@ -1488,8 +1488,9 @@ void mem_cgroup_uncharge_cache_page(struct page *page) 
	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);

}



#ifdef CONFIG_SWAP

/*

 * called from __delete_from_swap_cache() and drop "page" account.

 * called after __delete_from_swap_cache() and drop "page" account.

 * memcg information is recorded to swap_cgroup of "ent"

 */

void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
@@ -1506,6 +1507,7 @@ void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent) 
	if (memcg)

		css_put(&memcg->css);

}

#endif



#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP

/*

mm/swap_state.c

+1 −3
Original line number Diff line number Diff line
@@ -109,8 +109,6 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask) 
 */

void __delete_from_swap_cache(struct page *page)

{

	swp_entry_t ent = {.val = page_private(page)};



	VM_BUG_ON(!PageLocked(page));

	VM_BUG_ON(!PageSwapCache(page));

	VM_BUG_ON(PageWriteback(page));
@@ -121,7 +119,6 @@ void __delete_from_swap_cache(struct page *page) 
	total_swapcache_pages--;

	__dec_zone_page_state(page, NR_FILE_PAGES);

	INC_CACHE_INFO(del_total);

	mem_cgroup_uncharge_swapcache(page, ent);

}



/**
@@ -191,6 +188,7 @@ void delete_from_swap_cache(struct page *page) 
	__delete_from_swap_cache(page);

	spin_unlock_irq(&swapper_space.tree_lock);



	mem_cgroup_uncharge_swapcache(page, entry);

	swap_free(entry);

	page_cache_release(page);

}

mm/truncate.c

+1 −0
Original line number Diff line number Diff line
@@ -359,6 +359,7 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page) 
	BUG_ON(page_has_private(page));

	__remove_from_page_cache(page);

	spin_unlock_irq(&mapping->tree_lock);

	mem_cgroup_uncharge_cache_page(page);

	page_cache_release(page);	/* pagecache ref */

	return 1;

failed: