On Tue, Dec 20, 2011 at 01:17:10PM -0500, kosaki.motohiro@xxxxxxxxx wrote: > From: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > > commit 8aacc9f550 (mm/mempolicy.c: fix pgoff in mbind vma merge) is > slightly incorrect fix. > > Why? Think following case. > > 1. map 4 pages of a file at offset 0 > > [0123] > > 2. map 2 pages just after the first mapping of the same file but with > page offset 2 > > [0123][23] > > 3. mbind() 2 pages from the first mapping at offset 2. > mbind_range() should treat new vma is, > > [0123][23] > |23| > mbind vma > > but it does > > [0123][23] > |01| > mbind vma > > Oops. then, it makes wrong vma merge and splitting ([01][0123] or similar). > > This patch fixes it. > > [testcase] > test result - before the patch > > case4: 126: test failed. expect '2,4', actual '2,2,2' > case5: passed > case6: passed > case7: passed > case8: passed > case_n: 246: test failed. expect '4,2', actual '1,4' > > ------------[ cut here ]------------ > kernel BUG at mm/filemap.c:135! > invalid opcode: 0000 [#4] SMP DEBUG_PAGEALLOC > > (snip long bug on messages) > > test result - after the patch > > case4: passed > case5: passed > case6: passed > case7: passed > case8: passed > case_n: passed > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > Cc: Johannes Weiner <hannes@xxxxxxxxxxx> > Cc: Minchan Kim <minchan.kim@xxxxxxxxx> > CC: Caspar Zhang <caspar@xxxxxxxxxxxxxxx> Looks good to me now, thanks. Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Since this can corrupt virtual mappings and was released with 3.2, I think we also want this: Cc: stable@xxxxxxxxxx [3.2.x] -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>