| From 08d8447ae2bccf522295c2b3160a0adaba5dcdda Mon Sep 17 00:00:00 2001 |
| From: Clemens Ladisch <clemens@ladisch.de> |
| Date: Tue, 21 Jun 2011 22:09:50 +0200 |
| Subject: [PATCH] mm: fix wrong vmap address calculations with odd NR_CPUS |
| values |
| |
| commit f982f91516fa4cfd9d20518833cd04ad714585be upstream. |
| |
| 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> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| --- |
| mm/vmalloc.c | 7 ++++--- |
| 1 file changed, 4 insertions(+), 3 deletions(-) |
| |
| diff --git a/mm/vmalloc.c b/mm/vmalloc.c |
| index 20a402c..d44abdd 100644 |
| --- a/mm/vmalloc.c |
| +++ b/mm/vmalloc.c |
| @@ -671,9 +671,10 @@ 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) |
| |
| -- |
| 1.7.9.6 |
| |
