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| author | Andrew Morton <akpm@osdl.org> | 2006-05-15 09:43:59 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-05-15 11:20:55 -0700 |
| commit | ac924c6034d9095f95ee889f7e31bbb9145da0c2 (patch) | |
| tree | 2db4fc64a008ff2b81a0faf381d8c21ccc5006b2 /mm/page_alloc.c | |
| parent | 5afdbd6e84c7fbdaa7cfde4cbee0d3a5f4f56da2 (diff) | |
| download | lwn-ac924c6034d9095f95ee889f7e31bbb9145da0c2.tar.gz lwn-ac924c6034d9095f95ee889f7e31bbb9145da0c2.zip | |
[PATCH] setup_per_zone_pages_min() overflow fix
As pointed out in http://bugzilla.kernel.org/show_bug.cgi?id=6490, this
function can experience overflows on 32-bit machines, causing our response to
changed values of min_free_kbytes to go whacky.
Fixing it efficiently is all too hard, so fix it with 64-bit math instead.
Cc: Ake Sandgren <ake.sandgren@hpc2n.umu.se>
Cc: Martin Bligh <mbligh@google.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/page_alloc.c')
| -rw-r--r-- | mm/page_alloc.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ea77c999047e..813b4ec1298a 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -39,6 +39,7 @@ #include <linux/mempolicy.h> #include <asm/tlbflush.h> +#include <asm/div64.h> #include "internal.h" /* @@ -2566,9 +2567,11 @@ void setup_per_zone_pages_min(void) } for_each_zone(zone) { - unsigned long tmp; + u64 tmp; + spin_lock_irqsave(&zone->lru_lock, flags); - tmp = (pages_min * zone->present_pages) / lowmem_pages; + tmp = (u64)pages_min * zone->present_pages; + do_div(tmp, lowmem_pages); if (is_highmem(zone)) { /* * __GFP_HIGH and PF_MEMALLOC allocations usually don't @@ -2595,8 +2598,8 @@ void setup_per_zone_pages_min(void) zone->pages_min = tmp; } - zone->pages_low = zone->pages_min + tmp / 4; - zone->pages_high = zone->pages_min + tmp / 2; + zone->pages_low = zone->pages_min + (tmp >> 2); + zone->pages_high = zone->pages_min + (tmp >> 1); spin_unlock_irqrestore(&zone->lru_lock, flags); } |