Hi, 在 2024/01/18 2:17, Mikulas Patocka 写道:
The commit fa2bbff7b0b4 breaks the LVM2 test shell/integrity-caching.sh, so let's revert it. sysrq: Show Blocked State task:lvm state:D stack:0 pid:8275 tgid:8275 ppid:1373 flags:0x00000002 Call Trace: <TASK> __schedule+0x228/0x570 ? __percpu_ref_switch_mode+0xb7/0x1b0 schedule+0x29/0xa0 mddev_suspend+0xec/0x1a0 [md_mod]
We really need more information about the root cause here. If mddev_suspend() is waiting for this flush IO to be done, then why the flush IO can't finish? Thanks, Kuai
? housekeeping_test_cpu+0x30/0x30 dm_table_postsuspend_targets+0x34/0x50 [dm_mod] __dm_destroy+0x1c5/0x1e0 [dm_mod] ? table_clear+0xa0/0xa0 [dm_mod] dev_remove+0xd4/0x110 [dm_mod] ctl_ioctl+0x2e1/0x570 [dm_mod] dm_ctl_ioctl+0x5/0x10 [dm_mod] __x64_sys_ioctl+0x85/0xa0 do_syscall_64+0x5d/0x1a0 entry_SYSCALL_64_after_hwframe+0x46/0x4e Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> Fixes: fa2bbff7b0b4 ("md: synchronize flush io with array reconfiguration") --- drivers/md/md.c | 21 ++++++--------------- 1 file changed, 6 insertions(+), 15 deletions(-) Index: linux-2.6/drivers/md/md.c =================================================================== --- linux-2.6.orig/drivers/md/md.c +++ linux-2.6/drivers/md/md.c @@ -543,9 +543,6 @@ static void md_end_flush(struct bio *bio rdev_dec_pending(rdev, mddev);if (atomic_dec_and_test(&mddev->flush_pending)) {- /* The pair is percpu_ref_get() from md_flush_request() */ - percpu_ref_put(&mddev->active_io); - /* The pre-request flush has finished */ queue_work(md_wq, &mddev->flush_work); } @@ -565,7 +562,12 @@ static void submit_flushes(struct work_s rdev_for_each_rcu(rdev, mddev) if (rdev->raid_disk >= 0 && !test_bit(Faulty, &rdev->flags)) { + /* Take two references, one is dropped + * when request finishes, one after + * we reclaim rcu_read_lock + */ struct bio *bi; + atomic_inc(&rdev->nr_pending);atomic_inc(&rdev->nr_pending);rcu_read_unlock(); @@ -577,6 +579,7 @@ static void submit_flushes(struct work_s atomic_inc(&mddev->flush_pending); submit_bio(bi); rcu_read_lock(); + rdev_dec_pending(rdev, mddev); } rcu_read_unlock(); if (atomic_dec_and_test(&mddev->flush_pending)) @@ -629,18 +632,6 @@ bool md_flush_request(struct mddev *mdde /* new request after previous flush is completed */ if (ktime_after(req_start, mddev->prev_flush_start)) { WARN_ON(mddev->flush_bio); - /* - * Grab a reference to make sure mddev_suspend() will wait for - * this flush to be done. - * - * md_flush_reqeust() is called under md_handle_request() and - * 'active_io' is already grabbed, hence percpu_ref_is_zero() - * won't pass, percpu_ref_tryget_live() can't be used because - * percpu_ref_kill() can be called by mddev_suspend() - * concurrently. - */ - WARN_ON(percpu_ref_is_zero(&mddev->active_io)); - percpu_ref_get(&mddev->active_io); mddev->flush_bio = bio; bio = NULL; } .
