Messages in this thread Patch in this message | | | Subject | [PATCH] unevictable mlocked pages: initialize mm member of munlock mm_walk structure | From | Lee Schermerhorn <> | Date | Tue, 17 Jun 2008 16:00:43 -0400 |
| |
was: Re: [Bad page] trying to free locked page? (Re: [PATCH][RFC] fix kernel BUG at mm/migrate.c:719! in 2.6.26-rc5-mm3)
On Tue, 2008-06-17 at 14:29 -0400, Lee Schermerhorn wrote: > On Tue, 2008-06-17 at 18:15 +0900, Daisuke Nishimura wrote: > > On Tue, 17 Jun 2008 18:03:14 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > > > On Tue, 17 Jun 2008 16:47:09 +0900 > > > Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote: > > > > > > > On Tue, 17 Jun 2008 16:35:01 +0900, Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote: > > > > > Hi. > > > > > > > > > > I got this bug while migrating pages only a few times > > > > > via memory_migrate of cpuset. > > > > > > > > > > Unfortunately, even if this patch is applied, > > > > > I got bad_page problem after hundreds times of page migration > > > > > (I'll report it in another mail). > > > > > But I believe something like this patch is needed anyway. > > > > > > > > > > > > > I got bad_page after hundreds times of page migration. > > > > It seems that a locked page is being freed. > > I'm seeing *mlocked* pages [PG_mlocked] being freed now with my stress > load, with just the "if(!page->mapping) { } clause removed, as proposed > in your rfc patch in previous mail. Need to investigate this... > <snip>
This [freeing of mlocked pages] also occurs in unpatched 26-rc5-mm3.
Fixed by the following:
PATCH: fix munlock page table walk - now requires 'mm'
Against 2.6.26-rc5-mm3.
Incremental fix for: mlock-mlocked-pages-are-unevictable-fix.patch
Initialize the 'mm' member of the mm_walk structure, else the page table walk doesn't occur, and mlocked pages will not be munlocked. This is visible in the vmstats:
noreclaim_pgs_munlocked - should equal noreclaim_pgs_mlocked less (nr_mlock + noreclaim_pgs_cleared), but is always zero [munlock_vma_page() never called]
noreclaim_pgs_mlockfreed - should be zero [for debug only], but == noreclaim_pgs_mlocked - (nr_mlock + noreclaim_pgs_cleared)
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
mm/mlock.c | 2 ++ 1 file changed, 2 insertions(+)
Index: linux-2.6.26-rc5-mm3/mm/mlock.c =================================================================== --- linux-2.6.26-rc5-mm3.orig/mm/mlock.c 2008-06-17 15:20:57.000000000 -0400 +++ linux-2.6.26-rc5-mm3/mm/mlock.c 2008-06-17 15:23:17.000000000 -0400 @@ -318,6 +318,8 @@ static void __munlock_vma_pages_range(st VM_BUG_ON(start < vma->vm_start); VM_BUG_ON(end > vma->vm_end); + munlock_page_walk.mm = mm; + lru_add_drain_all(); /* push cached pages to LRU */ walk_page_range(start, end, &munlock_page_walk); lru_add_drain_all(); /* to update stats */
| |