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Commit 3f9e7949 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
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[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: default avatarHugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 2d1d43f6

mm/swapfile.c

+4 −3
Original line number Diff line number Diff line
@@ -1723,13 +1723,14 @@ get_swap_info_struct(unsigned type) 
 */

int valid_swaphandles(swp_entry_t entry, unsigned long *offset)

{

	int ret = 0, i = 1 << page_cluster;

	int our_page_cluster = page_cluster;

	int ret = 0, i = 1 << our_page_cluster;

	unsigned long toff;

	struct swap_info_struct *swapdev = swp_type(entry) + swap_info;



	if (!page_cluster)	/* no readahead */

	if (!our_page_cluster)	/* no readahead */

		return 0;

	toff = (swp_offset(entry) >> page_cluster) << page_cluster;

	toff = (swp_offset(entry) >> our_page_cluster) << our_page_cluster;

	if (!toff)		/* first page is swap header */

		toff++, i--;

	*offset = toff;