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authorDan Williams <dan.j.williams@intel.com>2009-03-04 00:57:25 -0700
committerDan Williams <dan.j.williams@intel.com>2009-03-04 00:57:25 -0700
commit5fd3a17ed456637a224cf4ca82b9ad9d005bc8d4 (patch)
tree24906c956159349cddecc43b3479d2a9add364df /drivers/md
parentfec6c6fec3e20637bee5d276fb61dd8b49a3f9cc (diff)
md: fix deadlock when stopping arrays
Resolve a deadlock when stopping redundant arrays, i.e. ones that require a call to sysfs_remove_group when shutdown. The deadlock is summarized below: Thread1 Thread2 ------- ------- read sysfs attribute stop array take mddev lock sysfs_remove_group sysfs_get_active wait for mddev lock wait for active Sysrq-w: -------- mdmon S 00000017 2212 4163 1 f1982ea8 00000046 2dcf6b85 00000017 c0b23100 f2f83ed0 c0b23100 f2f8413c c0b23100 c0b23100 c0b1fb98 f2f8413c 00000000 f2f8413c c0b23100 f2291ecc 00000002 c0b23100 00000000 00000017 f2f83ed0 f1982eac 00000046 c044d9dd Call Trace: [<c044d9dd>] ? debug_mutex_add_waiter+0x1d/0x58 [<c06ef451>] __mutex_lock_common+0x1d9/0x338 [<c06ef451>] ? __mutex_lock_common+0x1d9/0x338 [<c06ef5e3>] mutex_lock_interruptible_nested+0x33/0x3a [<c0634553>] ? mddev_lock+0x14/0x16 [<c0634553>] mddev_lock+0x14/0x16 [<c0634eda>] md_attr_show+0x2a/0x49 [<c04e9997>] sysfs_read_file+0x93/0xf9 mdadm D 00000017 2812 4177 1 f0401d78 00000046 430456f8 00000017 f0401d58 f0401d20 c0b23100 f2da2c4c c0b23100 c0b23100 c0b1fb98 f2da2c4c 0a10fc36 00000000 c0b23100 f0401d70 00000003 c0b23100 00000000 00000017 f2da29e0 00000001 00000002 00000000 Call Trace: [<c06eed1b>] schedule_timeout+0x1b/0x95 [<c06eed1b>] ? schedule_timeout+0x1b/0x95 [<c06eeb97>] ? wait_for_common+0x34/0xdc [<c044fa8a>] ? trace_hardirqs_on_caller+0x18/0x145 [<c044fbc2>] ? trace_hardirqs_on+0xb/0xd [<c06eec03>] wait_for_common+0xa0/0xdc [<c0428c7c>] ? default_wake_function+0x0/0x12 [<c06eeccc>] wait_for_completion+0x17/0x19 [<c04ea620>] sysfs_addrm_finish+0x19f/0x1d1 [<c04e920e>] sysfs_hash_and_remove+0x42/0x55 [<c04eb4db>] sysfs_remove_group+0x57/0x86 [<c0638086>] do_md_stop+0x13a/0x499 This has been there for a while, but is easier to trigger now that mdmon is closely watching sysfs. Cc: <stable@kernel.org> Reported-by: Jacek Danecki <jacek.danecki@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/md.c30
1 files changed, 18 insertions, 12 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 03b4cd0a634..a307f87eb90 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -214,12 +214,7 @@ static inline mddev_t *mddev_get(mddev_t *mddev)
return mddev;
}
-static void mddev_delayed_delete(struct work_struct *ws)
-{
- mddev_t *mddev = container_of(ws, mddev_t, del_work);
- kobject_del(&mddev->kobj);
- kobject_put(&mddev->kobj);
-}
+static void mddev_delayed_delete(struct work_struct *ws);
static void mddev_put(mddev_t *mddev)
{
@@ -3542,6 +3537,21 @@ static struct kobj_type md_ktype = {
int mdp_major = 0;
+static void mddev_delayed_delete(struct work_struct *ws)
+{
+ mddev_t *mddev = container_of(ws, mddev_t, del_work);
+
+ if (mddev->private == &md_redundancy_group) {
+ sysfs_remove_group(&mddev->kobj, &md_redundancy_group);
+ if (mddev->sysfs_action)
+ sysfs_put(mddev->sysfs_action);
+ mddev->sysfs_action = NULL;
+ mddev->private = NULL;
+ }
+ kobject_del(&mddev->kobj);
+ kobject_put(&mddev->kobj);
+}
+
static int md_alloc(dev_t dev, char *name)
{
static DEFINE_MUTEX(disks_mutex);
@@ -4033,13 +4043,9 @@ static int do_md_stop(mddev_t * mddev, int mode, int is_open)
mddev->queue->merge_bvec_fn = NULL;
mddev->queue->unplug_fn = NULL;
mddev->queue->backing_dev_info.congested_fn = NULL;
- if (mddev->pers->sync_request) {
- sysfs_remove_group(&mddev->kobj, &md_redundancy_group);
- if (mddev->sysfs_action)
- sysfs_put(mddev->sysfs_action);
- mddev->sysfs_action = NULL;
- }
module_put(mddev->pers->owner);
+ if (mddev->pers->sync_request)
+ mddev->private = &md_redundancy_group;
mddev->pers = NULL;
/* tell userspace to handle 'inactive' */
sysfs_notify_dirent(mddev->sysfs_state);