diff options
| author | Laura Abbott <lauraa@codeaurora.org> | 2013-01-11 14:31:51 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-01-11 14:54:55 -0800 |
| commit | c060f943d0929f3e429c5d9522290584f6281d6e (patch) | |
| tree | ccbc72cee7202d8591aa9c5fa55dcc465bbd2a35 /mm/bootmem.c | |
| parent | 6d92d4f6a74766cc885b18218268e0c47fbca399 (diff) | |
| download | linux-c060f943d0929f3e429c5d9522290584f6281d6e.tar.bz2 | |
mm: use aligned zone start for pfn_to_bitidx calculation
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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/bootmem.c')
0 files changed, 0 insertions, 0 deletions