[PATCH AUTOSEL 5.6 58/68] md: check arrays is suspended in mddev_detach before call quiesce operations

Sasha Levin
2020-04-10T03:47:48Z

From: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>

[ Upstream commit 6b40bec3b13278d21fa6c1ae7a0bdf2e550eed5f ]

Don't call quiesce(1) and quiesce(0) if array is already suspended,
otherwise in level_store, the array is writable after mddev_detach
in below part though the intention is to make array writable after
resume.

mddev_suspend(mddev);
mddev_detach(mddev);
...
mddev_resume(mddev);

And it also causes calltrace as follows in [1].

[48005.653834] WARNING: CPU: 1 PID: 45380 at kernel/kthread.c:510 kthread_park+0x77/0x90
[...]
[48005.653976] CPU: 1 PID: 45380 Comm: mdadm Tainted: G OE 5.4.10-arch1-1 #1
[48005.653979] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./J4105-ITX, BIOS P1.40 08/06/2018
[48005.653984] RIP: 0010:kthread_park+0x77/0x90
[48005.654015] Call Trace:
[48005.654039] r5l_quiesce+0x3c/0x70 [raid456]
[48005.654052] raid5_quiesce+0x228/0x2e0 [raid456]
[48005.654073] mddev_detach+0x30/0x70 [md_mod]
[48005.654090] level_store+0x202/0x670 [md_mod]
[48005.654099] ? security_capable+0x40/0x60
[48005.654114] md_attr_store+0x7b/0xc0 [md_mod]
[48005.654123] kernfs_fop_write+0xce/0x1b0
[48005.654132] vfs_write+0xb6/0x1a0
[48005.654138] ksys_write+0x67/0xe0
[48005.654146] do_syscall_64+0x4e/0x140
[48005.654155] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[48005.654161] RIP: 0033:0x7fa0c8737497

[1]: https://bugzilla.kernel.org/show_bug.cgi?id=206161

Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/md.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 469f551863bea..0b30ada971c14 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -6184,7 +6184,7 @@ EXPORT_SYMBOL_GPL(md_stop_writes);
static void mddev_detach(struct mddev *mddev)
{
md_bitmap_wait_behind_writes(mddev);
- if (mddev->pers && mddev->pers->quiesce) {
+ if (mddev->pers && mddev->pers->quiesce && !mddev->suspended) {
mddev->pers->quiesce(mddev, 1);
mddev->pers->quiesce(mddev, 0);
}
--
2.20.1