From: David Rientjes Date: Mon, 8 Oct 2012 23:34:03 +0000 (-0700) Subject: mm, thp: fix mapped pages avoiding unevictable list on mlock X-Git-Tag: v3.7-rc1~74^2~12 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b676b293fb48672904ee1b9828cb50b4eed01717;p=pandora-kernel.git mm, thp: fix mapped pages avoiding unevictable list on mlock When a transparent hugepage is mapped and it is included in an mlock() range, follow_page() incorrectly avoids setting the page's mlock bit and moving it to the unevictable lru. This is evident if you try to mlock(), munlock(), and then mlock() a range again. Currently: #define MAP_SIZE (4 << 30) /* 4GB */ void *ptr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0); mlock(ptr, MAP_SIZE); $ grep -E "Unevictable|Inactive\(anon" /proc/meminfo Inactive(anon): 6304 kB Unevictable: 4213924 kB munlock(ptr, MAP_SIZE); Inactive(anon): 4186252 kB Unevictable: 19652 kB mlock(ptr, MAP_SIZE); Inactive(anon): 4198556 kB Unevictable: 21684 kB Notice that less than 2MB was added to the unevictable list; this is because these pages in the range are not transparent hugepages since the 4GB range was allocated with mmap() and has no specific alignment. If posix_memalign() were used instead, unevictable would not have grown at all on the second mlock(). The fix is to call mlock_vma_page() so that the mlock bit is set and the page is added to the unevictable list. With this patch: mlock(ptr, MAP_SIZE); Inactive(anon): 4056 kB Unevictable: 4213940 kB munlock(ptr, MAP_SIZE); Inactive(anon): 4198268 kB Unevictable: 19636 kB mlock(ptr, MAP_SIZE); Inactive(anon): 4008 kB Unevictable: 4213940 kB Signed-off-by: David Rientjes Acked-by: Hugh Dickins Reviewed-by: Andrea Arcangeli Cc: Naoya Horiguchi Cc: KAMEZAWA Hiroyuki Cc: Johannes Weiner Cc: Michel Lespinasse Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed