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authorHugh Dickins <hugh@veritas.com>2006-09-29 05:01:26 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-09-29 12:18:23 -0400
commit3f9e7949f86dfe2bd9a1ad0604f78e7683c059de (patch)
treeaf710aa375e0f641ceec1bf7d4002ef33beeb571 /mm/swapfile.c
parent2d1d43f6a43b703587e759145f69467e7c6553a7 (diff)
[PATCH] valid_swaphandles() fix
akpm draws my attention to the fact that sysctl(VM_PAGE_CLUSTER) might conceivably change page_cluster to 0 while valid_swaphandles() is in the middle of using it, leading to an embarrassingly long loop: take a local snapshot of page_cluster and work with that. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/swapfile.c')
-rw-r--r--mm/swapfile.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index f1f5ec783781..a15def63f28f 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1723,13 +1723,14 @@ get_swap_info_struct(unsigned type)
1723 */ 1723 */
1724int valid_swaphandles(swp_entry_t entry, unsigned long *offset) 1724int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
1725{ 1725{
1726 int ret = 0, i = 1 << page_cluster; 1726 int our_page_cluster = page_cluster;
1727 int ret = 0, i = 1 << our_page_cluster;
1727 unsigned long toff; 1728 unsigned long toff;
1728 struct swap_info_struct *swapdev = swp_type(entry) + swap_info; 1729 struct swap_info_struct *swapdev = swp_type(entry) + swap_info;
1729 1730
1730 if (!page_cluster) /* no readahead */ 1731 if (!our_page_cluster) /* no readahead */
1731 return 0; 1732 return 0;
1732 toff = (swp_offset(entry) >> page_cluster) << page_cluster; 1733 toff = (swp_offset(entry) >> our_page_cluster) << our_page_cluster;
1733 if (!toff) /* first page is swap header */ 1734 if (!toff) /* first page is swap header */
1734 toff++, i--; 1735 toff++, i--;
1735 *offset = toff; 1736 *offset = toff;