[PATCH 4.9 147/148] md: free unused memory after bitmap resize

Greg Kroah-Hartman
2017-12-12T13:01:54Z

From: Zdenek Kabelac <zkabelac@redhat.com>

[ Upstream commit 0868b99c214a3d55486c700de7c3f770b7243e7c ]

When bitmap is resized, the old kalloced chunks just are not released
once the resized bitmap starts to use new space.

This fixes in particular kmemleak reports like this one:

unreferenced object 0xffff8f4311e9c000 (size 4096):
comm "lvm", pid 19333, jiffies 4295263268 (age 528.265s)
hex dump (first 32 bytes):
02 80 02 80 02 80 02 80 02 80 02 80 02 80 02 80 ................
02 80 02 80 02 80 02 80 02 80 02 80 02 80 02 80 ................
backtrace:
[<ffffffffa69471ca>] kmemleak_alloc+0x4a/0xa0
[<ffffffffa628c10e>] kmem_cache_alloc_trace+0x14e/0x2e0
[<ffffffffa676cfec>] bitmap_checkpage+0x7c/0x110
[<ffffffffa676d0c5>] bitmap_get_counter+0x45/0xd0
[<ffffffffa676d6b3>] bitmap_set_memory_bits+0x43/0xe0
[<ffffffffa676e41c>] bitmap_init_from_disk+0x23c/0x530
[<ffffffffa676f1ae>] bitmap_load+0xbe/0x160
[<ffffffffc04c47d3>] raid_preresume+0x203/0x2f0 [dm_raid]
[<ffffffffa677762f>] dm_table_resume_targets+0x4f/0xe0
[<ffffffffa6774b52>] dm_resume+0x122/0x140
[<ffffffffa6779b9f>] dev_suspend+0x18f/0x290
[<ffffffffa677a3a7>] ctl_ioctl+0x287/0x560
[<ffffffffa677a693>] dm_ctl_ioctl+0x13/0x20
[<ffffffffa62d6b46>] do_vfs_ioctl+0xa6/0x750
[<ffffffffa62d7269>] SyS_ioctl+0x79/0x90
[<ffffffffa6956d41>] entry_SYSCALL_64_fastpath+0x1f/0xc2

Signed-off-by: Zdenek Kabelac <zkabelac@redhat.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/md/bitmap.c | 9 +++++++++
1 file changed, 9 insertions(+)

--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -2084,6 +2084,7 @@ int bitmap_resize(struct bitmap *bitmap,
for (k = 0; k < page; k++) {
kfree(new_bp[k].map);
}
+ kfree(new_bp);

/* restore some fields from old_counts */
bitmap->counts.bp = old_counts.bp;
@@ -2134,6 +2135,14 @@ int bitmap_resize(struct bitmap *bitmap,
block += old_blocks;
}

+ if (bitmap->counts.bp != old_counts.bp) {
+ unsigned long k;
+ for (k = 0; k < old_counts.pages; k++)
+ if (!old_counts.bp[k].hijacked)
+ kfree(old_counts.bp[k].map);
+ kfree(old_counts.bp);
+ }
+
if (!init) {
int i;
while (block < (chunks << chunkshift)) {