[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>
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@ -1723,13 +1723,14 @@ get_swap_info_struct(unsigned type)
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*/
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int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
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{
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int ret = 0, i = 1 << page_cluster;
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int our_page_cluster = page_cluster;
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int ret = 0, i = 1 << our_page_cluster;
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unsigned long toff;
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struct swap_info_struct *swapdev = swp_type(entry) + swap_info;
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if (!page_cluster) /* no readahead */
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if (!our_page_cluster) /* no readahead */
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return 0;
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toff = (swp_offset(entry) >> page_cluster) << page_cluster;
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toff = (swp_offset(entry) >> our_page_cluster) << our_page_cluster;
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if (!toff) /* first page is swap header */
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toff++, i--;
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*offset = toff;
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