Please add commit 145e1a71e090 to stable

Please add commit 145e1a71e090 to stable

[Hugh Dickins]

Please add 4.17 commit 145e1a71e090575c74969e3daa8136d1e5b99fc8
("mm: fix the NULL mapping case in __isolate_lru_page()")
to the 4.16, 4.14, 4.9, 4.4, 3.18 and 3.2 stable kernel trees.

Two things happened after I'd sent it to Andrew without a stable tag:
1. Ivan posted an equivalent patch: after painstaking bisection, he
   had found the fixed commit to be what was causing strange blocking
   (surprising to the rest of us, we had imagined it just suboptimal).
2. The fixed commit arrived in five stable kernel releases (presumably
   arriving there by auto selection: which will in due course pick up
   this fix to it, but I don't know its cadence).

Thanks,
Hugh

From: Hugh Dickins <hughd@google.com>
Date: Fri, 1 Jun 2018 16:50:50 -0700

George Boole would have noticed a slight error in 4.16 commit
69d763fc6d3a ("mm: pin address_space before dereferencing it while
isolating an LRU page").  Fix it, to match both the comment above it,
and the original behaviour.

Although anonymous pages are not marked PageDirty at first, we have an
old habit of calling SetPageDirty when a page is removed from swap
cache: so there's a category of ex-swap pages that are easily
migratable, but were inadvertently excluded from compaction's async
migration in 4.16.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1805302014001.12558@eggly.anvils
Fixes: 69d763fc6d3a ("mm: pin address_space before dereferencing it while isolating an LRU page")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by:  Ivan Kalvachev <ikalvachev@gmail.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/vmscan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9b697323a88c..9270a4370d54 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1418,7 +1418,7 @@ int __isolate_lru_page(struct page *page, isolate_mode_t mode)
 				return ret;
 
 			mapping = page_mapping(page);
-			migrate_dirty = mapping && mapping->a_ops->migratepage;
+			migrate_dirty = !mapping || mapping->a_ops->migratepage;
 			unlock_page(page);
 			if (!migrate_dirty)
 				return ret;
-- 
1.8.4.5

Re: Please add commit 145e1a71e090 to stable

[Greg Kroah-Hartman]

On Sun, Jun 03, 2018 at 01:03:48PM -0700, Hugh Dickins wrote:
> Please add 4.17 commit 145e1a71e090575c74969e3daa8136d1e5b99fc8
> ("mm: fix the NULL mapping case in __isolate_lru_page()")
> to the 4.16, 4.14, 4.9, 4.4, 3.18 and 3.2 stable kernel trees.
> 
> Two things happened after I'd sent it to Andrew without a stable tag:
> 1. Ivan posted an equivalent patch: after painstaking bisection, he
>    had found the fixed commit to be what was causing strange blocking
>    (surprising to the rest of us, we had imagined it just suboptimal).
> 2. The fixed commit arrived in five stable kernel releases (presumably
>    arriving there by auto selection: which will in due course pick up
>    this fix to it, but I don't know its cadence).

Thanks for letting us know, now queued up for 4.16, 4.14, 4.9, 4.4, and
3.18.  3.2 is now end-of-life, but 3.16 is still alive, Ben can take
care of that.

thanks,

greg k-h