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authorHugh Dickins <hugh@veritas.com>2008-03-04 22:29:07 (GMT)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-03-05 00:35:15 (GMT)
commit9442ec9df40d952b0de185ae5638a74970388e01 (patch)
tree14b06d71203be119d93736464ca49f37ce402c1c /mm/memcontrol.c
parent98837c7f82ef78aa38f40462aa2fcac68fd3acbf (diff)
downloadlinux-9442ec9df40d952b0de185ae5638a74970388e01.tar.xz
memcg: bad page if page_cgroup when free
Replace free_hot_cold_page's VM_BUG_ON(page_get_page_cgroup(page)) by a "Bad page state" and clear: most users don't have CONFIG_DEBUG_VM on, and if it were set here, it'd likely cause corruption when the page is reused. Don't use page_assign_page_cgroup to clear it: that should be private to memcontrol.c, and always called with the lock taken; and memmap_init_zone doesn't need it either - like page->mapping and other pointers throughout the kernel, Linux assumes pointers in zeroed structures are NULL pointers. Instead use page_reset_bad_cgroup, added to memcontrol.h for this only. Signed-off-by: Hugh Dickins <hugh@veritas.com> Cc: David Rientjes <rientjes@google.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hirokazu Takahashi <taka@valinux.co.jp> Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Cc: Paul Menage <menage@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
-rw-r--r--mm/memcontrol.c27
1 files changed, 12 insertions, 15 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index afdd406..9e170d3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -140,11 +140,17 @@ struct mem_cgroup {
/*
* We use the lower bit of the page->page_cgroup pointer as a bit spin
- * lock. We need to ensure that page->page_cgroup is atleast two
- * byte aligned (based on comments from Nick Piggin)
+ * lock. We need to ensure that page->page_cgroup is at least two
+ * byte aligned (based on comments from Nick Piggin). But since
+ * bit_spin_lock doesn't actually set that lock bit in a non-debug
+ * uniprocessor kernel, we should avoid setting it here too.
*/
#define PAGE_CGROUP_LOCK_BIT 0x0
-#define PAGE_CGROUP_LOCK (1 << PAGE_CGROUP_LOCK_BIT)
+#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
+#define PAGE_CGROUP_LOCK (1 << PAGE_CGROUP_LOCK_BIT)
+#else
+#define PAGE_CGROUP_LOCK 0x0
+#endif
/*
* A page_cgroup page is associated with every page descriptor. The
@@ -271,19 +277,10 @@ static inline int page_cgroup_locked(struct page *page)
&page->page_cgroup);
}
-void page_assign_page_cgroup(struct page *page, struct page_cgroup *pc)
+static void page_assign_page_cgroup(struct page *page, struct page_cgroup *pc)
{
- int locked;
-
- /*
- * While resetting the page_cgroup we might not hold the
- * page_cgroup lock. free_hot_cold_page() is an example
- * of such a scenario
- */
- if (pc)
- VM_BUG_ON(!page_cgroup_locked(page));
- locked = (page->page_cgroup & PAGE_CGROUP_LOCK);
- page->page_cgroup = ((unsigned long)pc | locked);
+ VM_BUG_ON(!page_cgroup_locked(page));
+ page->page_cgroup = ((unsigned long)pc | PAGE_CGROUP_LOCK);
}
struct page_cgroup *page_get_page_cgroup(struct page *page)