On 7/20/20 7:26 AM, NeilBrown wrote:

On Sun, Jul 19 2020, Zhao Heming wrote:

quoted

update_array_info misses calling module_put when removing cluster bitmap.

steps to reproduce:

node1 # mdadm -C /dev/md0 -b clustered -e 1.2 -n 2 -l mirror /dev/sda
/dev/sdb
mdadm: array /dev/md0 started.
node1 # lsmod | egrep "dlm|md_|raid1"
md_cluster             28672  1
dlm                   212992  14 md_cluster
configfs               57344  2 dlm
raid1                  53248  1
md_mod                176128  2 raid1,md_cluster
node1 # mdadm -G /dev/md0 -b none
node1 # lsmod | egrep "dlm|md_|raid1"
md_cluster             28672  1 <== should be zero
dlm                   212992  9 md_cluster
configfs               57344  2 dlm
raid1                  53248  1
md_mod                176128  2 raid1,md_cluster
node1 # mdadm -G /dev/md0 -b clustered
node1 # lsmod | egrep "dlm|md_|raid1"
md_cluster             28672  2 <== increase
dlm                   212992  14 md_cluster
configfs               57344  2 dlm
raid1                  53248  1
md_mod                176128  2 raid1,md_cluster
node1 # mdadm -G /dev/md0 -b none
node1 # mdadm -G /dev/md0 -b clustered
node1 # lsmod | egrep "dlm|md_|raid1"
md_cluster             28672  3 <== increase
dlm                   212992  14 md_cluster
configfs               57344  2 dlm
raid1                  53248  1
md_mod                176128  2 raid1,md_cluster

Signed-off-by: Zhao Heming <redacted>
---
  drivers/md/md.c | 1 +
  1 file changed, 1 insertion(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index e20f1d5a5261..ca791387e54d 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c

@@ -7363,6 +7363,7 @@ static int update_array_info(struct mddev *mddev, mdu_array_info_t *info)
  
  				mddev->bitmap_info.nodes = 0;
  				md_cluster_ops->leave(mddev);
+				module_put(md_cluster_mod);
  				mddev->safemode_delay = DEFAULT_SAFEMODE_DELAY;

I would make this a call to "md_cluster_stop()", and move the reset of
->safemode_delay" in there, but either way this is correct and needed.

   Reviewed-by: NeilBrown [off-list ref]

Thanks,
NeilBrown

Thank you for your review.
If put module_put() in md_cluster_stop(), "mddev->bitmap_info.nodes = 0" also needs to put in md_cluster_stop().
the "bitmap_info.nodes = 0" makes mddev_is_clustered() false and will close the door to call md_cluster_stop().

quoted

  			}
  			mddev_suspend(mddev);
-- 
2.25.0