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 <akinobu.mita@gmail.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/frontswap.c b/mm/frontswap.c
index 538367ef137270b768481a42e2bf2ee504d0ada2..1b24bdcb3197492674b0d6d0c128f9928fb977b1 100644 (file)
--- 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
index 6c340d908b274c7855b3abd0bdeadff56c8ffc92..746af55b8455ce0e9280b81c78e0ee5f2316f5d4 100644 (file)
--- 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))) {