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authorLaura Abbott <lauraa@codeaurora.org>2013-01-12 02:31:51 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-01-17 20:50:43 +0400
commitce19422296fb5fb5997d81e1b0043d771def7996 (patch)
tree92b8292798661ad6d3d4e4e4a8649949b30872cf /arch
parentc0b96525363543a1ba6a277546ebc26ad9a53aa1 (diff)
downloadlinux-ce19422296fb5fb5997d81e1b0043d771def7996.tar.xz
mm: use aligned zone start for pfn_to_bitidx calculation
commit c060f943d0929f3e429c5d9522290584f6281d6e upstream. The current calculation in pfn_to_bitidx assumes that (pfn - zone->zone_start_pfn) >> pageblock_order will return the same bit for all pfn in a pageblock. If zone_start_pfn is not aligned to pageblock_nr_pages, this may not always be correct. Consider the following with pageblock order = 10, zone start 2MB: pfn | pfn - zone start | (pfn - zone start) >> page block order ---------------------------------------------------------------- 0x26000 | 0x25e00 | 0x97 0x26100 | 0x25f00 | 0x97 0x26200 | 0x26000 | 0x98 0x26300 | 0x26100 | 0x98 This means that calling {get,set}_pageblock_migratetype on a single page will not set the migratetype for the full block. Fix this by rounding down zone_start_pfn when doing the bitidx calculation. For our use case, the effects of this bug were mostly tied to the fact that CMA allocations would either take a long time or fail to happen. Depending on the driver using CMA, this could result in anything from visual glitches to application failures. Signed-off-by: Laura Abbott <lauraa@codeaurora.org> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
0 files changed, 0 insertions, 0 deletions