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Message-Id: <20200714231026.67443-1-junxiao.bi@oracle.com>
Date: Tue, 14 Jul 2020 16:10:26 -0700
From: Junxiao Bi <junxiao.bi@...cle.com>
To: linux-raid@...r.kernel.org
Cc: song@...nel.org, linux-kernel@...r.kernel.org
Subject: [PATCH V2] md: fix deadlock causing by sysfs_notify
The following deadlock was captured. The first process is holding 'kernfs_mutex'
and hung by io. The io was staging in 'r1conf.pending_bio_list' of raid1 device,
this pending bio list would be flushed by second process 'md127_raid1', but
it was hung by 'kernfs_mutex'. Using sysfs_notify_dirent_safe() to replace
sysfs_notify() can fix it. There were other sysfs_notify() invoked from io
path, removed all of them.
PID: 40430 TASK: ffff8ee9c8c65c40 CPU: 29 COMMAND: "probe_file"
#0 [ffffb87c4df37260] __schedule at ffffffff9a8678ec
#1 [ffffb87c4df372f8] schedule at ffffffff9a867f06
#2 [ffffb87c4df37310] io_schedule at ffffffff9a0c73e6
#3 [ffffb87c4df37328] __dta___xfs_iunpin_wait_3443 at ffffffffc03a4057 [xfs]
#4 [ffffb87c4df373a0] xfs_iunpin_wait at ffffffffc03a6c79 [xfs]
#5 [ffffb87c4df373b0] __dta_xfs_reclaim_inode_3357 at ffffffffc039a46c [xfs]
#6 [ffffb87c4df37400] xfs_reclaim_inodes_ag at ffffffffc039a8b6 [xfs]
#7 [ffffb87c4df37590] xfs_reclaim_inodes_nr at ffffffffc039bb33 [xfs]
#8 [ffffb87c4df375b0] xfs_fs_free_cached_objects at ffffffffc03af0e9 [xfs]
#9 [ffffb87c4df375c0] super_cache_scan at ffffffff9a287ec7
#10 [ffffb87c4df37618] shrink_slab at ffffffff9a1efd93
#11 [ffffb87c4df37700] shrink_node at ffffffff9a1f5968
#12 [ffffb87c4df37788] do_try_to_free_pages at ffffffff9a1f5ea2
#13 [ffffb87c4df377f0] try_to_free_mem_cgroup_pages at ffffffff9a1f6445
#14 [ffffb87c4df37880] try_charge at ffffffff9a26cc5f
#15 [ffffb87c4df37920] memcg_kmem_charge_memcg at ffffffff9a270f6a
#16 [ffffb87c4df37958] new_slab at ffffffff9a251430
#17 [ffffb87c4df379c0] ___slab_alloc at ffffffff9a251c85
#18 [ffffb87c4df37a80] __slab_alloc at ffffffff9a25635d
#19 [ffffb87c4df37ac0] kmem_cache_alloc at ffffffff9a251f89
#20 [ffffb87c4df37b00] alloc_inode at ffffffff9a2a2b10
#21 [ffffb87c4df37b20] iget_locked at ffffffff9a2a4854
#22 [ffffb87c4df37b60] kernfs_get_inode at ffffffff9a311377
#23 [ffffb87c4df37b80] kernfs_iop_lookup at ffffffff9a311e2b
#24 [ffffb87c4df37ba8] lookup_slow at ffffffff9a290118
#25 [ffffb87c4df37c10] walk_component at ffffffff9a291e83
#26 [ffffb87c4df37c78] path_lookupat at ffffffff9a293619
#27 [ffffb87c4df37cd8] filename_lookup at ffffffff9a2953af
#28 [ffffb87c4df37de8] user_path_at_empty at ffffffff9a295566
#29 [ffffb87c4df37e10] vfs_statx at ffffffff9a289787
#30 [ffffb87c4df37e70] SYSC_newlstat at ffffffff9a289d5d
#31 [ffffb87c4df37f18] sys_newlstat at ffffffff9a28a60e
#32 [ffffb87c4df37f28] do_syscall_64 at ffffffff9a003949
#33 [ffffb87c4df37f50] entry_SYSCALL_64_after_hwframe at ffffffff9aa001ad
RIP: 00007f617a5f2905 RSP: 00007f607334f838 RFLAGS: 00000246
RAX: ffffffffffffffda RBX: 00007f6064044b20 RCX: 00007f617a5f2905
RDX: 00007f6064044b20 RSI: 00007f6064044b20 RDI: 00007f6064005890
RBP: 00007f6064044aa0 R8: 0000000000000030 R9: 000000000000011c
R10: 0000000000000013 R11: 0000000000000246 R12: 00007f606417e6d0
R13: 00007f6064044aa0 R14: 00007f6064044b10 R15: 00000000ffffffff
ORIG_RAX: 0000000000000006 CS: 0033 SS: 002b
PID: 927 TASK: ffff8f15ac5dbd80 CPU: 42 COMMAND: "md127_raid1"
#0 [ffffb87c4df07b28] __schedule at ffffffff9a8678ec
#1 [ffffb87c4df07bc0] schedule at ffffffff9a867f06
#2 [ffffb87c4df07bd8] schedule_preempt_disabled at ffffffff9a86825e
#3 [ffffb87c4df07be8] __mutex_lock at ffffffff9a869bcc
#4 [ffffb87c4df07ca0] __mutex_lock_slowpath at ffffffff9a86a013
#5 [ffffb87c4df07cb0] mutex_lock at ffffffff9a86a04f
#6 [ffffb87c4df07cc8] kernfs_find_and_get_ns at ffffffff9a311d83
#7 [ffffb87c4df07cf0] sysfs_notify at ffffffff9a314b3a
#8 [ffffb87c4df07d18] md_update_sb at ffffffff9a688696
#9 [ffffb87c4df07d98] md_update_sb at ffffffff9a6886d5
#10 [ffffb87c4df07da8] md_check_recovery at ffffffff9a68ad9c
#11 [ffffb87c4df07dd0] raid1d at ffffffffc01f0375 [raid1]
#12 [ffffb87c4df07ea0] md_thread at ffffffff9a680348
#13 [ffffb87c4df07f08] kthread at ffffffff9a0b8005
#14 [ffffb87c4df07f50] ret_from_fork at ffffffff9aa00344
Signed-off-by: Junxiao Bi <junxiao.bi@...cle.com>
---
v2 <- v1
- fix sysfs_notify for sysfs file 'level' to align styles with others.
---
drivers/md/md-bitmap.c | 2 +-
drivers/md/md.c | 44 ++++++++++++++++++++++++++++--------------
drivers/md/md.h | 8 +++++++-
drivers/md/raid10.c | 2 +-
drivers/md/raid5.c | 6 +++---
5 files changed, 42 insertions(+), 20 deletions(-)
diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index 95a5f3757fa3..d61b524ae440 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -1631,7 +1631,7 @@ void md_bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector, bool force)
s += blocks;
}
bitmap->last_end_sync = jiffies;
- sysfs_notify(&bitmap->mddev->kobj, NULL, "sync_completed");
+ sysfs_notify_dirent_safe(bitmap->mddev->sysfs_completed);
}
EXPORT_SYMBOL(md_bitmap_cond_end_sync);
diff --git a/drivers/md/md.c b/drivers/md/md.c
index f567f536b529..fee8943ead7b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2444,6 +2444,10 @@ static int bind_rdev_to_array(struct md_rdev *rdev, struct mddev *mddev)
if (sysfs_create_link(&rdev->kobj, ko, "block"))
/* failure here is OK */;
rdev->sysfs_state = sysfs_get_dirent_safe(rdev->kobj.sd, "state");
+ rdev->sysfs_unack_badblocks =
+ sysfs_get_dirent_safe(rdev->kobj.sd, "unacknowledged_bad_blocks");
+ rdev->sysfs_badblocks =
+ sysfs_get_dirent_safe(rdev->kobj.sd, "bad_blocks");
list_add_rcu(&rdev->same_set, &mddev->disks);
bd_link_disk_holder(rdev->bdev, mddev->gendisk);
@@ -2477,7 +2481,11 @@ static void unbind_rdev_from_array(struct md_rdev *rdev)
rdev->mddev = NULL;
sysfs_remove_link(&rdev->kobj, "block");
sysfs_put(rdev->sysfs_state);
+ sysfs_put(rdev->sysfs_unack_badblocks);
+ sysfs_put(rdev->sysfs_badblocks);
rdev->sysfs_state = NULL;
+ rdev->sysfs_unack_badblocks = NULL;
+ rdev->sysfs_badblocks = NULL;
rdev->badblocks.count = 0;
/* We need to delay this, otherwise we can deadlock when
* writing to 'remove' to "dev/state". We also need
@@ -2822,7 +2830,7 @@ void md_update_sb(struct mddev *mddev, int force_change)
goto repeat;
wake_up(&mddev->sb_wait);
if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
- sysfs_notify(&mddev->kobj, NULL, "sync_completed");
+ sysfs_notify_dirent_safe(mddev->sysfs_completed);
rdev_for_each(rdev, mddev) {
if (test_and_clear_bit(FaultRecorded, &rdev->flags))
@@ -4075,7 +4083,7 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
mddev_resume(mddev);
if (!mddev->thread)
md_update_sb(mddev, 1);
- sysfs_notify(&mddev->kobj, NULL, "level");
+ sysfs_notify_dirent_safe(mddev->sysfs_level);
md_new_event(mddev);
rv = len;
out_unlock:
@@ -4828,7 +4836,7 @@ action_store(struct mddev *mddev, const char *page, size_t len)
}
if (err)
return err;
- sysfs_notify(&mddev->kobj, NULL, "degraded");
+ sysfs_notify_dirent_safe(mddev->sysfs_degraded);
} else {
if (cmd_match(page, "check"))
set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
@@ -5534,6 +5542,13 @@ static void md_free(struct kobject *ko)
if (mddev->sysfs_state)
sysfs_put(mddev->sysfs_state);
+ if (mddev->sysfs_completed)
+ sysfs_put(mddev->sysfs_completed);
+ if (mddev->sysfs_degraded)
+ sysfs_put(mddev->sysfs_degraded);
+ if (mddev->sysfs_level)
+ sysfs_put(mddev->sysfs_level);
+
if (mddev->gendisk)
del_gendisk(mddev->gendisk);
@@ -5695,6 +5710,9 @@ static int md_alloc(dev_t dev, char *name)
if (!error && mddev->kobj.sd) {
kobject_uevent(&mddev->kobj, KOBJ_ADD);
mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state");
+ mddev->sysfs_completed = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_completed");
+ mddev->sysfs_degraded = sysfs_get_dirent_safe(mddev->kobj.sd, "degraded");
+ mddev->sysfs_level = sysfs_get_dirent_safe(mddev->kobj.sd, "level");
}
mddev_put(mddev);
return error;
@@ -6049,7 +6067,7 @@ static int do_md_run(struct mddev *mddev)
kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
sysfs_notify_dirent_safe(mddev->sysfs_state);
sysfs_notify_dirent_safe(mddev->sysfs_action);
- sysfs_notify(&mddev->kobj, NULL, "degraded");
+ sysfs_notify_dirent_safe(mddev->sysfs_degraded);
out:
clear_bit(MD_NOT_READY, &mddev->flags);
return err;
@@ -8767,7 +8785,7 @@ void md_do_sync(struct md_thread *thread)
} else
mddev->curr_resync = 3; /* no longer delayed */
mddev->curr_resync_completed = j;
- sysfs_notify(&mddev->kobj, NULL, "sync_completed");
+ sysfs_notify_dirent_safe(mddev->sysfs_completed);
md_new_event(mddev);
update_time = jiffies;
@@ -8795,7 +8813,7 @@ void md_do_sync(struct md_thread *thread)
mddev->recovery_cp = j;
update_time = jiffies;
set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
- sysfs_notify(&mddev->kobj, NULL, "sync_completed");
+ sysfs_notify_dirent_safe(mddev->sysfs_completed);
}
while (j >= mddev->resync_max &&
@@ -8902,7 +8920,7 @@ void md_do_sync(struct md_thread *thread)
!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
mddev->curr_resync > 3) {
mddev->curr_resync_completed = mddev->curr_resync;
- sysfs_notify(&mddev->kobj, NULL, "sync_completed");
+ sysfs_notify_dirent_safe(mddev->sysfs_completed);
}
mddev->pers->sync_request(mddev, max_sectors, &skipped);
@@ -9032,7 +9050,7 @@ static int remove_and_add_spares(struct mddev *mddev,
}
if (removed && mddev->kobj.sd)
- sysfs_notify(&mddev->kobj, NULL, "degraded");
+ sysfs_notify_dirent_safe(mddev->sysfs_degraded);
if (this && removed)
goto no_add;
@@ -9315,8 +9333,7 @@ void md_reap_sync_thread(struct mddev *mddev)
/* success...*/
/* activate any spares */
if (mddev->pers->spare_active(mddev)) {
- sysfs_notify(&mddev->kobj, NULL,
- "degraded");
+ sysfs_notify_dirent_safe(mddev->sysfs_degraded);
set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
}
}
@@ -9406,8 +9423,7 @@ int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
if (rv == 0) {
/* Make sure they get written out promptly */
if (test_bit(ExternalBbl, &rdev->flags))
- sysfs_notify(&rdev->kobj, NULL,
- "unacknowledged_bad_blocks");
+ sysfs_notify_dirent_safe(rdev->sysfs_unack_badblocks);
sysfs_notify_dirent_safe(rdev->sysfs_state);
set_mask_bits(&mddev->sb_flags, 0,
BIT(MD_SB_CHANGE_CLEAN) | BIT(MD_SB_CHANGE_PENDING));
@@ -9428,7 +9444,7 @@ int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
s += rdev->data_offset;
rv = badblocks_clear(&rdev->badblocks, s, sectors);
if ((rv == 0) && test_bit(ExternalBbl, &rdev->flags))
- sysfs_notify(&rdev->kobj, NULL, "bad_blocks");
+ sysfs_notify_dirent_safe(rdev->sysfs_badblocks);
return rv;
}
EXPORT_SYMBOL_GPL(rdev_clear_badblocks);
@@ -9658,7 +9674,7 @@ static int read_rdev(struct mddev *mddev, struct md_rdev *rdev)
if (rdev->recovery_offset == MaxSector &&
!test_bit(In_sync, &rdev->flags) &&
mddev->pers->spare_active(mddev))
- sysfs_notify(&mddev->kobj, NULL, "degraded");
+ sysfs_notify_dirent_safe(mddev->sysfs_degraded);
put_page(swapout);
return 0;
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 612814d07d35..1f6b89483bcf 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -126,7 +126,10 @@ struct md_rdev {
struct kernfs_node *sysfs_state; /* handle for 'state'
* sysfs entry */
-
+ /* handle for 'unacknowledged_bad_blocks' sysfs dentry */
+ struct kernfs_node *sysfs_unack_badblocks;
+ /* handle for 'bad_blocks' sysfs dentry */
+ struct kernfs_node *sysfs_badblocks;
struct badblocks badblocks;
struct {
@@ -420,6 +423,9 @@ struct mddev {
* file in sysfs.
*/
struct kernfs_node *sysfs_action; /* handle for 'sync_action' */
+ struct kernfs_node *sysfs_completed; /*handle for 'sync_completed' */
+ struct kernfs_node *sysfs_degraded; /*handle for 'degraded' */
+ struct kernfs_node *sysfs_level; /*handle for 'level' */
struct work_struct del_work; /* used for delayed sysfs removal */
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index ec136e44aef7..b2de47eac238 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -4454,7 +4454,7 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
sector_nr = conf->reshape_progress;
if (sector_nr) {
mddev->curr_resync_completed = sector_nr;
- sysfs_notify(&mddev->kobj, NULL, "sync_completed");
+ sysfs_notify_dirent_safe(mddev->sysfs_completed);
*skipped = 1;
return sector_nr;
}
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index ab8067f9ce8c..09f59611dd9b 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5799,7 +5799,7 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
sector_div(sector_nr, new_data_disks);
if (sector_nr) {
mddev->curr_resync_completed = sector_nr;
- sysfs_notify(&mddev->kobj, NULL, "sync_completed");
+ sysfs_notify_dirent_safe(mddev->sysfs_completed);
*skipped = 1;
retn = sector_nr;
goto finish;
@@ -5913,7 +5913,7 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
conf->reshape_safe = mddev->reshape_position;
spin_unlock_irq(&conf->device_lock);
wake_up(&conf->wait_for_overlap);
- sysfs_notify(&mddev->kobj, NULL, "sync_completed");
+ sysfs_notify_dirent_safe(mddev->sysfs_completed);
}
INIT_LIST_HEAD(&stripes);
@@ -6020,7 +6020,7 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
conf->reshape_safe = mddev->reshape_position;
spin_unlock_irq(&conf->device_lock);
wake_up(&conf->wait_for_overlap);
- sysfs_notify(&mddev->kobj, NULL, "sync_completed");
+ sysfs_notify_dirent_safe(mddev->sysfs_completed);
}
ret:
return retn;
--
2.20.1 (Apple Git-117)
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