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authorOmar Sandoval <osandov@fb.com>2018-04-02 15:58:31 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-02 20:52:27 -0700
commit21035965f60b0502fc6537b232839389bb4ce664 (patch)
treeb4c969cd182d8e30dd9b0123c945f200ab50f14a /init/main.c
parentf5a8eb632b562bd9c16c389f5db3a5260fba4157 (diff)
bitmap: fix memset optimization on big-endian systems
Commit 2a98dc028f91 ("include/linux/bitmap.h: turn bitmap_set and bitmap_clear into memset when possible") introduced an optimization to bitmap_{set,clear}() which uses memset() when the start and length are constants aligned to a byte. This is wrong on big-endian systems; our bitmaps are arrays of unsigned long, so bit n is not at byte n / 8 in memory. This was caught by the Btrfs selftests, but the bitmap selftests also fail when run on a big-endian machine. We can still use memset if the start and length are aligned to an unsigned long, so do that on big-endian. The same problem applies to the memcmp in bitmap_equal(), so fix it there, too. Fixes: 2a98dc028f91 ("include/linux/bitmap.h: turn bitmap_set and bitmap_clear into memset when possible") Fixes: 2c6deb01525a ("bitmap: use memcmp optimisation in more situations") Cc: stable@kernel.org Reported-by: "Erhard F." <erhard_f@mailbox.org> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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