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Linus Torvalds authored
Commit c060f943 ("mm: use aligned zone start for pfn_to_bitidx calculation") fixed out calculation of the index into the pageblock bitmap when a !SPARSEMEM zome was not aligned to pageblock_nr_pages. However, the _allocation_ of that bitmap had never taken this alignment requirement into accout, so depending on the exact size and alignment of the zone, the use of that index could then access past the allocation, resulting in some very subtle memory corruption. This was reported (and bisected) by Ingo Molnar: one of his random config builds would hang with certain very specific kernel command line options. In the meantime, commit c060f943 has been marked for stable, so this fix needs to be back-ported to the stable kernels that backported the commit to use the right alignment. Bisected-and-tested-by:
Ingo Molnar <mingo@kernel.org> Acked-by:
Mel Gorman <mgorman@suse.de> Cc: stable@kernel.org Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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