4.19-stable review patch. If anyone has any objections, please let me know.
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From: Yu Kuai yukuai3@huawei.com
[ 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@redhat.com Closes: https://lore.kernel.org/all/71ba5272-ab07-43ba-8232-d2da642acb4e@redhat.com/ Signed-off-by: Yu Kuai yukuai3@huawei.com Link: https://lore.kernel.org/r/20240422065824.2516-1-yukuai1@huaweicloud.com Signed-off-by: Song Liu song@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/md-bitmap.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c index 7ca81e917aef4..6cbf4a069652c 100644 --- a/drivers/md/md-bitmap.c +++ b/drivers/md/md-bitmap.c @@ -1358,7 +1358,7 @@ __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) { @@ -1367,6 +1367,7 @@ __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); @@ -1375,8 +1376,7 @@ __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)