frontswap: fix incorrect zeroing and allocation size for frontswap_map

The bitmap accessed by bitops must have enough size to hold the required numbers of bits rounded up to a multiple of BITS_PER_LONG. And the bitmap must not be zeroed by memset() if the number of bits cleared is not a multiple of BITS_PER_LONG. This fixes incorrect zeroing and allocation size for frontswap_map. The incorrect zeroing part doesn't cause any problem because frontswap_map is freed just after zeroing. But the wrongly calculated allocation size may cause the problem. For 32bit systems, the allocation size of frontswap_map is about twice as large as required size. For 64bit systems, the allocation size is smaller than requeired if the number of bits is not a multiple of BITS_PER_LONG. Signed-off-by: Akinobu Mita <[email protected]> Cc: Konrad Rzeszutek Wilk <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
jix · Jun 12, 2013 · 7b57976 · 7b57976
1 parent 736f320
commit 7b57976
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Showing 2 changed files with 2 additions and 2 deletions.
diff --git a/mm/frontswap.c b/mm/frontswap.c
@@ -319,7 +319,7 @@ void __frontswap_invalidate_area(unsigned type)
 			return;
 		frontswap_ops->invalidate_area(type);
 		atomic_set(&sis->frontswap_pages, 0);
-		memset(sis->frontswap_map, 0, sis->max / sizeof(long));
+		bitmap_zero(sis->frontswap_map, sis->max);
 	}
 	clear_bit(type, need_init);
 }

diff --git a/mm/swapfile.c b/mm/swapfile.c
@@ -2116,7 +2116,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	}
 	/* frontswap enabled? set up bit-per-page map for frontswap */
 	if (frontswap_enabled)
-		frontswap_map = vzalloc(maxpages / sizeof(long));
+		frontswap_map = vzalloc(BITS_TO_LONGS(maxpages) * sizeof(long));
 
 	if (p->bdev) {
 		if (blk_queue_nonrot(bdev_get_queue(p->bdev))) {