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| author | Clemens Ladisch <clemens@ladisch.de> | 2011-06-21 22:09:50 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-08-14 12:32:52 -0700 |
| commit | f982f91516fa4cfd9d20518833cd04ad714585be (patch) | |
| tree | 15c7992ad6e54fbda868a026afd5ecf98f9b1bca /mm | |
| parent | 97c24d1d455df17ca3ef281d1a290988f4686643 (diff) | |
| download | lwn-f982f91516fa4cfd9d20518833cd04ad714585be.tar.gz lwn-f982f91516fa4cfd9d20518833cd04ad714585be.zip | |
mm: fix wrong vmap address calculations with odd NR_CPUS values
Commit db64fe02258f ("mm: rewrite vmap layer") introduced code that does
address calculations under the assumption that VMAP_BLOCK_SIZE is a
power of two. However, this might not be true if CONFIG_NR_CPUS is not
set to a power of two.
Wrong vmap_block index/offset values could lead to memory corruption.
However, this has never been observed in practice (or never been
diagnosed correctly); what caught this was the BUG_ON in vb_alloc() that
checks for inconsistent vmap_block indices.
To fix this, ensure that VMAP_BLOCK_SIZE always is a power of two.
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=31572
Reported-by: Pavel Kysilka <goldenfish@linuxsoft.cz>
Reported-by: Matias A. Fonzo <selk@dragora.org>
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: 2.6.28+ <stable@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/vmalloc.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 464621d18eb2..7ef0903058ee 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -725,9 +725,10 @@ static void free_unmap_vmap_area_addr(unsigned long addr) #define VMAP_BBMAP_BITS_MIN (VMAP_MAX_ALLOC*2) #define VMAP_MIN(x, y) ((x) < (y) ? (x) : (y)) /* can't use min() */ #define VMAP_MAX(x, y) ((x) > (y) ? (x) : (y)) /* can't use max() */ -#define VMAP_BBMAP_BITS VMAP_MIN(VMAP_BBMAP_BITS_MAX, \ - VMAP_MAX(VMAP_BBMAP_BITS_MIN, \ - VMALLOC_PAGES / NR_CPUS / 16)) +#define VMAP_BBMAP_BITS \ + VMAP_MIN(VMAP_BBMAP_BITS_MAX, \ + VMAP_MAX(VMAP_BBMAP_BITS_MIN, \ + VMALLOC_PAGES / roundup_pow_of_two(NR_CPUS) / 16)) #define VMAP_BLOCK_SIZE (VMAP_BBMAP_BITS * PAGE_SIZE) |