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| author | Vlastimil Babka <vbabka@suse.cz> | 2019-10-14 14:12:07 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-10-29 09:22:32 +0100 |
| commit | 48b8ba3a73535618d1b844a594be3033548e8656 (patch) | |
| tree | cc550bc59751787d0d4ea80d8651cd551dee4955 /mm | |
| parent | 6815408c1a20e3e68cbe5564fc6573bd7ff24582 (diff) | |
| download | linux-stable-48b8ba3a73535618d1b844a594be3033548e8656.tar.gz linux-stable-48b8ba3a73535618d1b844a594be3033548e8656.tar.bz2 linux-stable-48b8ba3a73535618d1b844a594be3033548e8656.zip | |
mm, compaction: fix wrong pfn handling in __reset_isolation_pfn()
commit a2e9a5afce080226edbf1882d63d99bf32070e9e upstream.
Florian and Dave reported [1] a NULL pointer dereference in
__reset_isolation_pfn(). While the exact cause is unclear, staring at
the code revealed two bugs, which might be related.
One bug is that if zone starts in the middle of pageblock, block_page
might correspond to different pfn than block_pfn, and then the
pfn_valid_within() checks will check different pfn's than those accessed
via struct page. This might result in acessing an unitialized page in
CONFIG_HOLES_IN_ZONE configs.
The other bug is that end_page refers to the first page of next
pageblock and not last page of current pageblock. The online and valid
check is then wrong and with sections, the while (page < end_page) loop
might wander off actual struct page arrays.
[1] https://lore.kernel.org/linux-xfs/87o8z1fvqu.fsf@mid.deneb.enyo.de/
Link: http://lkml.kernel.org/r/20191008152915.24704-1-vbabka@suse.cz
Fixes: 6b0868c820ff ("mm/compaction.c: correct zone boundary handling when resetting pageblock skip hints")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Florian Weimer <fw@deneb.enyo.de>
Reported-by: Dave Chinner <david@fromorbit.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org>
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 'mm')
| -rw-r--r-- | mm/compaction.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/mm/compaction.c b/mm/compaction.c index 1e994920e6ff..5ab9c2b22693 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -270,14 +270,15 @@ __reset_isolation_pfn(struct zone *zone, unsigned long pfn, bool check_source, /* Ensure the start of the pageblock or zone is online and valid */ block_pfn = pageblock_start_pfn(pfn); - block_page = pfn_to_online_page(max(block_pfn, zone->zone_start_pfn)); + block_pfn = max(block_pfn, zone->zone_start_pfn); + block_page = pfn_to_online_page(block_pfn); if (block_page) { page = block_page; pfn = block_pfn; } /* Ensure the end of the pageblock or zone is online and valid */ - block_pfn += pageblock_nr_pages; + block_pfn = pageblock_end_pfn(pfn) - 1; block_pfn = min(block_pfn, zone_end_pfn(zone) - 1); end_page = pfn_to_online_page(block_pfn); if (!end_page) @@ -303,7 +304,7 @@ __reset_isolation_pfn(struct zone *zone, unsigned long pfn, bool check_source, page += (1 << PAGE_ALLOC_COSTLY_ORDER); pfn += (1 << PAGE_ALLOC_COSTLY_ORDER); - } while (page < end_page); + } while (page <= end_page); return false; } |