[PATCH 07/24] HWPOISON: comment the possible set_page_dirty() race

[Wu Fengguang]

CC: Andi Kleen <andi@xxxxxxxxxxxxxx> 
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
 mm/memory-failure.c |    2 ++
 1 file changed, 2 insertions(+)

--- linux-mm.orig/mm/memory-failure.c	2009-11-30 11:11:25.000000000 +0800
+++ linux-mm/mm/memory-failure.c	2009-11-30 11:12:41.000000000 +0800
@@ -667,6 +667,8 @@ static int hwpoison_user_mappings(struct
 	/*
 	 * Propagate the dirty bit from PTEs to struct page first, because we
 	 * need this to decide if we should kill or just drop the page.
+	 * XXX: the dirty test could be racy: set_page_dirty() may not always
+	 * be called inside page lock (it's recommended but not enforced).
 	 */
 	mapping = page_mapping(p);
 	if (!PageDirty(p) && mapping && mapping_cap_writeback_dirty(mapping)) {


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