From: David Sloan <david.sloan@xxxxxxxxxxxxx> commit 5e8daf906f890560df430d30617c692a794acb73 upstream. A race condition still exists when removing and re-creating md devices in test cases. However, it is only seen on some setups. The race condition was tracked down to a reference still being held to the kobject by the rdev in the md_rdev_misc_wq which will be released in rdev_delayed_delete(). md_alloc() waits for previous deletions by waiting on the md_misc_wq, but the md_rdev_misc_wq may still be holding a reference to a recently removed device. To fix this, also flush the md_rdev_misc_wq in md_alloc(). Signed-off-by: David Sloan <david.sloan@xxxxxxxxxxxxx> [logang@xxxxxxxxxxxx: rewrote commit message] Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx> Signed-off-by: Song Liu <song@xxxxxxxxxx> Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx> --- Hi Greg, We found the problem also exists on v5.10, so could you please pick it up for v5.10 ? Thanks. drivers/md/md.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/md/md.c b/drivers/md/md.c index 3038e7ecb7e1..c0b34637bd66 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -5683,6 +5683,7 @@ static int md_alloc(dev_t dev, char *name) * completely removed (mddev_delayed_delete). */ flush_workqueue(md_misc_wq); + flush_workqueue(md_rdev_misc_wq); mutex_lock(&disks_mutex); error = -EEXIST; -- 2.29.2
