This is a note to let you know that I've just added the patch titled
md: fix resync softlockup when bitmap size is less than array size
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
md-fix-resync-softlockup-when-bitmap-size-is-less-th.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 66957caf6196b3ac72cce1a73ecad8e0ec3f791d
Author: Yu Kuai <yukuai3@xxxxxxxxxx>
Date: Mon Apr 22 14:58:24 2024 +0800
md: fix resync softlockup when bitmap size is less than array size
[ Upstream commit f0e729af2eb6bee9eb58c4df1087f14ebaefe26b ]
Is is reported that for dm-raid10, lvextend + lvchange --syncaction will
trigger following softlockup:
kernel:watchdog: BUG: soft lockup - CPU#3 stuck for 26s! [mdX_resync:6976]
CPU: 7 PID: 3588 Comm: mdX_resync Kdump: loaded Not tainted 6.9.0-rc4-next-20240419 #1
RIP: 0010:_raw_spin_unlock_irq+0x13/0x30
Call Trace:
<TASK>
md_bitmap_start_sync+0x6b/0xf0
raid10_sync_request+0x25c/0x1b40 [raid10]
md_do_sync+0x64b/0x1020
md_thread+0xa7/0x170
kthread+0xcf/0x100
ret_from_fork+0x30/0x50
ret_from_fork_asm+0x1a/0x30
And the detailed process is as follows:
md_do_sync
j = mddev->resync_min
while (j < max_sectors)
sectors = raid10_sync_request(mddev, j, &skipped)
if (!md_bitmap_start_sync(..., &sync_blocks))
// md_bitmap_start_sync set sync_blocks to 0
return sync_blocks + sectors_skippe;
// sectors = 0;
j += sectors;
// j never change
Root cause is that commit 301867b1c168 ("md/raid10: check
slab-out-of-bounds in md_bitmap_get_counter") return early from
md_bitmap_get_counter(), without setting returned blocks.
Fix this problem by always set returned blocks from
md_bitmap_get_counter"(), as it used to be.
Noted that this patch just fix the softlockup problem in kernel, the
case that bitmap size doesn't match array size still need to be fixed.
Fixes: 301867b1c168 ("md/raid10: check slab-out-of-bounds in md_bitmap_get_counter")
Reported-and-tested-by: Nigel Croxon <ncroxon@xxxxxxxxxx>
Closes: https://lore.kernel.org/all/71ba5272-ab07-43ba-8232-d2da642acb4e@xxxxxxxxxx/
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240422065824.2516-1-yukuai1@xxxxxxxxxxxxxxx
Signed-off-by: Song Liu <song@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index a4976ceae8688..ee67da44641b5 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -1427,7 +1427,7 @@ __acquires(bitmap->lock)
sector_t chunk = offset >> bitmap->chunkshift;
unsigned long page = chunk >> PAGE_COUNTER_SHIFT;
unsigned long pageoff = (chunk & PAGE_COUNTER_MASK) << COUNTER_BYTE_SHIFT;
- sector_t csize;
+ sector_t csize = ((sector_t)1) << bitmap->chunkshift;
int err;
if (page >= bitmap->pages) {
@@ -1436,6 +1436,7 @@ __acquires(bitmap->lock)
* End-of-device while looking for a whole page or
* user set a huge number to sysfs bitmap_set_bits.
*/
+ *blocks = csize - (offset & (csize - 1));
return NULL;
}
err = md_bitmap_checkpage(bitmap, page, create, 0);
@@ -1444,8 +1445,7 @@ __acquires(bitmap->lock)
bitmap->bp[page].map == NULL)
csize = ((sector_t)1) << (bitmap->chunkshift +
PAGE_COUNTER_SHIFT);
- else
- csize = ((sector_t)1) << bitmap->chunkshift;
+
*blocks = csize - (offset & (csize - 1));
if (err < 0)
