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    SubjectRe: [PATCH] mm: compaction: Abort compaction if too many pages are isolated and caller is asynchronous
    On Tue, May 31, 2011 at 11:37:35PM +0900, Minchan Kim wrote:
    > On Tue, May 31, 2011 at 04:14:02PM +0200, Andrea Arcangeli wrote:
    > > On Tue, May 31, 2011 at 10:33:40PM +0900, Minchan Kim wrote:
    > > > I checked them before sending patch but I got failed to find strange things. :(
    > >
    > > My review also doesn't show other bugs in migrate_pages callers like
    > > that one.
    > >
    > > > Now I am checking the page's SwapBacked flag can be changed
    > > > between before and after of migrate_pages so accounting of NR_ISOLATED_XX can
    > > > make mistake. I am approaching the failure, too. Hmm.
    > >
    > > When I checked that, I noticed the ClearPageSwapBacked in swapcache if
    > > radix insertion fails, but that happens before adding the page in the
    > > LRU so it shouldn't have a chance to be isolated.
    >
    > True.
    >
    > >
    > > So far I only noticed an unsafe page_count in
    > > vmscan.c:isolate_lru_pages but that should at worst result in a
    > > invalid pointer dereference as random result from that page_count is
    > > not going to hurt and I think it's only a theoretical issue.
    >
    >
    > Yes. You find a new BUG.
    > It seems to be related to this problem but it should be solved although

    typo : It doesn't seem to be.


    -
    Kind regards
    Minchan Kim


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