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    SubjectRe: CMA broken in next-20120926
    Hi,

    On 09/28/2012 11:37 AM, Mel Gorman wrote:
    >> I hope this patch fixes the bug. If this patch fixes the problem
    >> but has some problem about description or someone has better idea,
    >> feel free to modify and resend to akpm, Please.
    >>
    >
    > A full revert is overkill. Can the following patch be tested as a
    > potential replacement please?
    >
    > ---8<---
    > mm: compaction: Iron out isolate_freepages_block() and isolate_freepages_range() -fix1
    >
    > CMA is reported to be broken in next-20120926. Minchan Kim pointed out
    > that this was due to nr_scanned != total_isolated in the case of CMA
    > because PageBuddy pages are one scan but many isolations in CMA. This
    > patch should address the problem.
    >
    > This patch is a fix for
    > mm-compaction-acquire-the-zone-lock-as-late-as-possible-fix-2.patch
    >
    > Signed-off-by: Mel Gorman <mgorman@suse.de>

    linux-next + this patch alone also works for me.

    Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>

    > ---
    > mm/compaction.c | 5 +++--
    > 1 file changed, 3 insertions(+), 2 deletions(-)
    >
    > diff --git a/mm/compaction.c b/mm/compaction.c
    > index 8250b69..d6e260a 100644
    > --- a/mm/compaction.c
    > +++ b/mm/compaction.c
    > @@ -282,6 +282,7 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
    > {
    > int nr_scanned = 0, total_isolated = 0;
    > struct page *cursor, *valid_page = NULL;
    > + unsigned long nr_strict_required = end_pfn - blockpfn;
    > unsigned long flags;
    > bool locked = false;
    >
    > @@ -343,10 +344,10 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
    >
    > /*
    > * If strict isolation is requested by CMA then check that all the
    > - * pages scanned were isolated. If there were any failures, 0 is
    > + * pages requested were isolated. If there were any failures, 0 is
    > * returned and CMA will fail.
    > */
    > - if (strict && nr_scanned != total_isolated)
    > + if (strict && nr_strict_required != total_isolated)
    > total_isolated = 0;
    >
    > if (locked)
    >


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