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: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Daisuke 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6 changed files with 15 additions and 7 deletions
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@ -437,6 +437,11 @@ static inline int mem_cgroup_cache_charge_swapin(struct page *page,
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return 0;
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}
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static inline void
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mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
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{
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}
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#endif /* CONFIG_SWAP */
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#endif /* __KERNEL__*/
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#endif /* _LINUX_SWAP_H */
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@ -121,7 +121,6 @@ void __remove_from_page_cache(struct page *page)
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mapping->nrpages--;
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__dec_zone_page_state(page, NR_FILE_PAGES);
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BUG_ON(page_mapped(page));
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mem_cgroup_uncharge_cache_page(page);
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/*
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* Some filesystems seem to re-dirty the page even after
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@ -145,6 +144,7 @@ void remove_from_page_cache(struct page *page)
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spin_lock_irq(&mapping->tree_lock);
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__remove_from_page_cache(page);
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spin_unlock_irq(&mapping->tree_lock);
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mem_cgroup_uncharge_cache_page(page);
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}
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static int sync_page(void *word)
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@ -476,13 +476,13 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
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if (likely(!error)) {
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mapping->nrpages++;
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__inc_zone_page_state(page, NR_FILE_PAGES);
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spin_unlock_irq(&mapping->tree_lock);
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} else {
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page->mapping = NULL;
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spin_unlock_irq(&mapping->tree_lock);
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mem_cgroup_uncharge_cache_page(page);
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page_cache_release(page);
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}
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spin_unlock_irq(&mapping->tree_lock);
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radix_tree_preload_end();
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} else
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mem_cgroup_uncharge_cache_page(page);
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@ -1488,8 +1488,9 @@ void mem_cgroup_uncharge_cache_page(struct page *page)
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__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);
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}
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#ifdef CONFIG_SWAP
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/*
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* called from __delete_from_swap_cache() and drop "page" account.
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* called after __delete_from_swap_cache() and drop "page" account.
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* memcg information is recorded to swap_cgroup of "ent"
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*/
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void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
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@ -1506,6 +1507,7 @@ void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
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if (memcg)
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css_put(&memcg->css);
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}
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#endif
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#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
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/*
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@ -109,8 +109,6 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
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*/
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void __delete_from_swap_cache(struct page *page)
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{
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swp_entry_t ent = {.val = page_private(page)};
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VM_BUG_ON(!PageLocked(page));
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VM_BUG_ON(!PageSwapCache(page));
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VM_BUG_ON(PageWriteback(page));
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@ -121,7 +119,6 @@ void __delete_from_swap_cache(struct page *page)
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total_swapcache_pages--;
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__dec_zone_page_state(page, NR_FILE_PAGES);
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INC_CACHE_INFO(del_total);
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mem_cgroup_uncharge_swapcache(page, ent);
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}
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/**
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@ -191,6 +188,7 @@ void delete_from_swap_cache(struct page *page)
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__delete_from_swap_cache(page);
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spin_unlock_irq(&swapper_space.tree_lock);
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mem_cgroup_uncharge_swapcache(page, entry);
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swap_free(entry);
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page_cache_release(page);
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}
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@ -359,6 +359,7 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
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BUG_ON(page_has_private(page));
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__remove_from_page_cache(page);
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spin_unlock_irq(&mapping->tree_lock);
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mem_cgroup_uncharge_cache_page(page);
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page_cache_release(page); /* pagecache ref */
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return 1;
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failed:
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@ -470,10 +470,12 @@ static int __remove_mapping(struct address_space *mapping, struct page *page)
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swp_entry_t swap = { .val = page_private(page) };
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__delete_from_swap_cache(page);
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spin_unlock_irq(&mapping->tree_lock);
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mem_cgroup_uncharge_swapcache(page, swap);
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swap_free(swap);
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} else {
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__remove_from_page_cache(page);
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spin_unlock_irq(&mapping->tree_lock);
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mem_cgroup_uncharge_cache_page(page);
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}
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return 1;
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