Re: [PATCH v12 1/1] md: generate CHANGE uevents for md device

[Yu Kuai <yukuai1@xxxxxxxxxxxxxxx>]

Hi,

在 2024/08/26 22:28, Kinga Stefaniuk 写道:
> In mdadm commit 49b69533e8 ("mdmonitor: check if udev has finished
> events processing") mdmonitor has been learnt to wait for udev to finish
> processing, and later in commit 9935cf0f64f3 ("Mdmonitor: Improve udev
> event handling") pooling for MD events on /proc/mdstat file has been
> deprecated because relying on udev events is more reliable and less bug
> prone (we are not competing with udev).
>
> After those changes we are still observing missing mdmonitor events in
> some scenarios, especially SpareEvent is likely to be missed. With this
> patch MD will be able to generate more change uevents and wakeup
> mdmonitor more frequently to give it possibility to notice events.
> MD has md_new_events() functionality to trigger events and with this
> patch this function is extended to generate udev CHANGE uevents. It
> cannot be done directly because this function is called on interrupts
> context, so appropriate workqueue is created. Uevents are less time
> critical, it is safe to use workqueue. It is limited to CHANGE event as
> there is no need to generate other uevents for now.
> With this change, mdmonitor events are less likely to be missed. Our
> internal tests suite confirms that, mdmonitor reliability is (again)
> improved.
> Start using irq methods on all_mddevs_lock, because it can be reached
> by interrupt context.
>
> Signed-off-by: Mateusz Grzonka <mateusz.grzonka@xxxxxxxxx>
> Signed-off-by: Kinga Stefaniuk <kinga.stefaniuk@xxxxxxxxx>
>
> ---
> v12: change lock spin_lock/unlock methods on all_mddevs_lock
> v11: use irq methods to lock/unlock all_mddevs_lock
> v10: move mddev_get into md_new_event
> v9: add using md_wq and fix if (sync) condition
> v8: fix possible conflict with del_work by adding spin_lock,
>      change default sync value to true, now false only on md_error
> v7: add new work struct for these events, use md_misc_wq workqueue,
>      fix work cancellation
> v6: use another workqueue and only on md_error, make configurable
>      if kobject_uevent is run immediately on event or queued
> v5: fix flush_work missing and commit message fixes
> v4: add more detailed commit message
> v3: fix problems with calling function from interrupt context,
>      add work_queue and queue events notification
> v2: resolve merge conflicts with applying the patch
>
> Signed-off-by: Kinga Stefaniuk <kinga.stefaniuk@xxxxxxxxx>
> ---
>   drivers/md/md.c     | 144 ++++++++++++++++++++++++++------------------
>   drivers/md/md.h     |   3 +-
>   drivers/md/raid10.c |   2 +-
>   drivers/md/raid5.c  |   2 +-
>   4 files changed, 91 insertions(+), 60 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index d3a837506a36..530ac80be7ba 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -107,6 +107,7 @@ static int remove_and_add_spares(struct mddev *mddev,
>   static void mddev_detach(struct mddev *mddev);
>   static void export_rdev(struct md_rdev *rdev, struct mddev *mddev);
>   static void md_wakeup_thread_directly(struct md_thread __rcu *thread);
> +static inline struct mddev *mddev_get(struct mddev *mddev);
>   
>   /*
>    * Default number of read corrections we'll attempt on an rdev
> @@ -323,6 +324,24 @@ static int start_readonly;
>    */
>   static bool create_on_open = true;
>   
> +/*
> + * Enables to iterate over all existing md arrays
> + * all_mddevs_lock protects this list.
> + */
> +static LIST_HEAD(all_mddevs);
> +static DEFINE_SPINLOCK(all_mddevs_lock);
> +
> +/*
> + * Send every new event to the userspace.
> + */
> +static void md_kobject_uevent_fn(struct work_struct *work)
> +{
> +	struct mddev *mddev = container_of(work, struct mddev, uevent_work);
> +
> +	kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
> +	mddev_put(mddev);
> +}
> +
>   /*
>    * We have a system wide 'event count' that is incremented
>    * on any 'interesting' event, and readers of /proc/mdstat
> @@ -335,20 +354,30 @@ static bool create_on_open = true;
>    */
>   static DECLARE_WAIT_QUEUE_HEAD(md_event_waiters);
>   static atomic_t md_event_count;
> -void md_new_event(void)
> +
> +void md_new_event(struct mddev *mddev, bool sync)
>   {
>   	atomic_inc(&md_event_count);
>   	wake_up(&md_event_waiters);
> +
> +	if (mddev_is_dm(mddev))
> +		return;
> +
> +	if (!sync) {
> +		unsigned long flags;
> +
> +		spin_lock_irqsave(&mddev->lock, flags);

The lock is wrong, mddev_get() should be protected by all_mddev_lock.
> +		mddev = mddev_get(mddev);
> +		spin_unlock_irqrestore(&mddev->lock, flags);
> +		if (mddev == NULL)
> +			return;
> +		queue_work(md_wq, &mddev->uevent_work);
> +		return;
> +	}
> +	kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
>   }
>   EXPORT_SYMBOL_GPL(md_new_event);
>   
> -/*
> - * Enables to iterate over all existing md arrays
> - * all_mddevs_lock protects this list.
> - */
> -static LIST_HEAD(all_mddevs);
> -static DEFINE_SPINLOCK(all_mddevs_lock);
> -
>   static bool is_md_suspended(struct mddev *mddev)
>   {
>   	return percpu_ref_is_dying(&mddev->active_io);
> @@ -720,7 +749,7 @@ void mddev_put(struct mddev *mddev)
>   		return;

As I said in the last version, atomic_dec_and_lock() must switch to
irq version as well.

atomic_dec_and_lock_irqsave()
...
spin_unlock_riqrestore()

Thanks,
Kuai

>   
>   	__mddev_put(mddev);
> -	spin_unlock(&all_mddevs_lock);
> +	spin_unlock_irq(&all_mddevs_lock);
>   }
>   
>   static void md_safemode_timeout(struct timer_list *t);
> @@ -773,6 +802,7 @@ int mddev_init(struct mddev *mddev)
>   	mddev->resync_max = MaxSector;
>   	mddev->level = LEVEL_NONE;
>   
> +	INIT_WORK(&mddev->uevent_work, md_kobject_uevent_fn);
>   	INIT_WORK(&mddev->sync_work, md_start_sync);
>   	INIT_WORK(&mddev->del_work, mddev_delayed_delete);
>   
> @@ -835,7 +865,7 @@ static struct mddev *mddev_alloc(dev_t unit)
>   	if (error)
>   		goto out_free_new;
>   
> -	spin_lock(&all_mddevs_lock);
> +	spin_lock_irq(&all_mddevs_lock);
>   	if (unit) {
>   		error = -EEXIST;
>   		if (mddev_find_locked(unit))
> @@ -856,11 +886,11 @@ static struct mddev *mddev_alloc(dev_t unit)
>   	}
>   
>   	list_add(&new->all_mddevs, &all_mddevs);
> -	spin_unlock(&all_mddevs_lock);
> +	spin_unlock_irq(&all_mddevs_lock);
>   	return new;
>   
>   out_destroy_new:
> -	spin_unlock(&all_mddevs_lock);
> +	spin_unlock_irq(&all_mddevs_lock);
>   	mddev_destroy(new);
>   out_free_new:
>   	kfree(new);
> @@ -869,9 +899,9 @@ static struct mddev *mddev_alloc(dev_t unit)
>   
>   static void mddev_free(struct mddev *mddev)
>   {
> -	spin_lock(&all_mddevs_lock);
> +	spin_lock_irq(&all_mddevs_lock);
>   	list_del(&mddev->all_mddevs);
> -	spin_unlock(&all_mddevs_lock);
> +	spin_unlock_irq(&all_mddevs_lock);
>   
>   	mddev_destroy(mddev);
>   	kfree(mddev);
> @@ -2898,7 +2928,7 @@ static int add_bound_rdev(struct md_rdev *rdev)
>   	if (mddev->degraded)
>   		set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
>   	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
> -	md_new_event();
> +	md_new_event(mddev, true);
>   	return 0;
>   }
>   
> @@ -3015,7 +3045,7 @@ state_store(struct md_rdev *rdev, const char *buf, size_t len)
>   				md_kick_rdev_from_array(rdev);
>   				if (mddev->pers)
>   					set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
> -				md_new_event();
> +				md_new_event(mddev, true);
>   			}
>   		}
>   	} else if (cmd_match(buf, "writemostly")) {
> @@ -3366,19 +3396,19 @@ static bool md_rdev_overlaps(struct md_rdev *rdev)
>   	struct mddev *mddev;
>   	struct md_rdev *rdev2;
>   
> -	spin_lock(&all_mddevs_lock);
> +	spin_lock_irq(&all_mddevs_lock);
>   	list_for_each_entry(mddev, &all_mddevs, all_mddevs) {
>   		if (test_bit(MD_DELETED, &mddev->flags))
>   			continue;
>   		rdev_for_each(rdev2, mddev) {
>   			if (rdev != rdev2 && rdev->bdev == rdev2->bdev &&
>   			    md_rdevs_overlap(rdev, rdev2)) {
> -				spin_unlock(&all_mddevs_lock);
> +				spin_unlock_irq(&all_mddevs_lock);
>   				return true;
>   			}
>   		}
>   	}
> -	spin_unlock(&all_mddevs_lock);
> +	spin_unlock_irq(&all_mddevs_lock);
>   	return false;
>   }
>   
> @@ -4131,7 +4161,7 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
>   	if (!mddev->thread)
>   		md_update_sb(mddev, 1);
>   	sysfs_notify_dirent_safe(mddev->sysfs_level);
> -	md_new_event();
> +	md_new_event(mddev, true);
>   	rv = len;
>   out_unlock:
>   	mddev_unlock_and_resume(mddev);
> @@ -4658,7 +4688,7 @@ new_dev_store(struct mddev *mddev, const char *buf, size_t len)
>   		export_rdev(rdev, mddev);
>   	mddev_unlock_and_resume(mddev);
>   	if (!err)
> -		md_new_event();
> +		md_new_event(mddev, true);
>   	return err ? err : len;
>   }
>   
> @@ -5727,12 +5757,12 @@ md_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
>   
>   	if (!entry->show)
>   		return -EIO;
> -	spin_lock(&all_mddevs_lock);
> +	spin_lock_irq(&all_mddevs_lock);
>   	if (!mddev_get(mddev)) {
> -		spin_unlock(&all_mddevs_lock);
> +		spin_unlock_irq(&all_mddevs_lock);
>   		return -EBUSY;
>   	}
> -	spin_unlock(&all_mddevs_lock);
> +	spin_unlock_irq(&all_mddevs_lock);
>   
>   	rv = entry->show(mddev, page);
>   	mddev_put(mddev);
> @@ -5751,12 +5781,12 @@ md_attr_store(struct kobject *kobj, struct attribute *attr,
>   		return -EIO;
>   	if (!capable(CAP_SYS_ADMIN))
>   		return -EACCES;
> -	spin_lock(&all_mddevs_lock);
> +	spin_lock_irq(&all_mddevs_lock);
>   	if (!mddev_get(mddev)) {
> -		spin_unlock(&all_mddevs_lock);
> +		spin_unlock_irq(&all_mddevs_lock);
>   		return -EBUSY;
>   	}
> -	spin_unlock(&all_mddevs_lock);
> +	spin_unlock_irq(&all_mddevs_lock);
>   	rv = entry->store(mddev, page, length);
>   	mddev_put(mddev);
>   	return rv;
> @@ -5901,16 +5931,16 @@ struct mddev *md_alloc(dev_t dev, char *name)
>   		/* Need to ensure that 'name' is not a duplicate.
>   		 */
>   		struct mddev *mddev2;
> -		spin_lock(&all_mddevs_lock);
> +		spin_lock_irq(&all_mddevs_lock);
>   
>   		list_for_each_entry(mddev2, &all_mddevs, all_mddevs)
>   			if (mddev2->gendisk &&
>   			    strcmp(mddev2->gendisk->disk_name, name) == 0) {
> -				spin_unlock(&all_mddevs_lock);
> +				spin_unlock_irq(&all_mddevs_lock);
>   				error = -EEXIST;
>   				goto out_free_mddev;
>   			}
> -		spin_unlock(&all_mddevs_lock);
> +		spin_unlock_irq(&all_mddevs_lock);
>   	}
>   	if (name && dev)
>   		/*
> @@ -6276,7 +6306,7 @@ int md_run(struct mddev *mddev)
>   	if (mddev->sb_flags)
>   		md_update_sb(mddev, 0);
>   
> -	md_new_event();
> +	md_new_event(mddev, true);
>   	return 0;
>   
>   bitmap_abort:
> @@ -6635,7 +6665,7 @@ static int do_md_stop(struct mddev *mddev, int mode)
>   		if (mddev->hold_active == UNTIL_STOP)
>   			mddev->hold_active = 0;
>   	}
> -	md_new_event();
> +	md_new_event(mddev, true);
>   	sysfs_notify_dirent_safe(mddev->sysfs_state);
>   	return 0;
>   }
> @@ -7131,7 +7161,7 @@ static int hot_remove_disk(struct mddev *mddev, dev_t dev)
>   	set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
>   	if (!mddev->thread)
>   		md_update_sb(mddev, 1);
> -	md_new_event();
> +	md_new_event(mddev, true);
>   
>   	return 0;
>   busy:
> @@ -7202,7 +7232,7 @@ static int hot_add_disk(struct mddev *mddev, dev_t dev)
>   	 * array immediately.
>   	 */
>   	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
> -	md_new_event();
> +	md_new_event(mddev, true);
>   	return 0;
>   
>   abort_export:
> @@ -7971,9 +8001,9 @@ static int md_open(struct gendisk *disk, blk_mode_t mode)
>   	struct mddev *mddev;
>   	int err;
>   
> -	spin_lock(&all_mddevs_lock);
> +	spin_lock_irq(&all_mddevs_lock);
>   	mddev = mddev_get(disk->private_data);
> -	spin_unlock(&all_mddevs_lock);
> +	spin_unlock_irq(&all_mddevs_lock);
>   	if (!mddev)
>   		return -ENODEV;
>   
> @@ -8176,7 +8206,7 @@ void md_error(struct mddev *mddev, struct md_rdev *rdev)
>   	}
>   	if (mddev->event_work.func)
>   		queue_work(md_misc_wq, &mddev->event_work);
> -	md_new_event();
> +	md_new_event(mddev, false);
>   }
>   EXPORT_SYMBOL(md_error);
>   
> @@ -8354,7 +8384,7 @@ static void *md_seq_start(struct seq_file *seq, loff_t *pos)
>   	__acquires(&all_mddevs_lock)
>   {
>   	seq->poll_event = atomic_read(&md_event_count);
> -	spin_lock(&all_mddevs_lock);
> +	spin_lock_irq(&all_mddevs_lock);
>   
>   	return seq_list_start_head(&all_mddevs, *pos);
>   }
> @@ -8367,7 +8397,7 @@ static void *md_seq_next(struct seq_file *seq, void *v, loff_t *pos)
>   static void md_seq_stop(struct seq_file *seq, void *v)
>   	__releases(&all_mddevs_lock)
>   {
> -	spin_unlock(&all_mddevs_lock);
> +	spin_unlock_irq(&all_mddevs_lock);
>   }
>   
>   static int md_seq_show(struct seq_file *seq, void *v)
> @@ -8387,7 +8417,7 @@ static int md_seq_show(struct seq_file *seq, void *v)
>   	if (!mddev_get(mddev))
>   		return 0;
>   
> -	spin_unlock(&all_mddevs_lock);
> +	spin_unlock_irq(&all_mddevs_lock);
>   	spin_lock(&mddev->lock);
>   	if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) {
>   		seq_printf(seq, "%s : %sactive", mdname(mddev),
> @@ -8458,7 +8488,7 @@ static int md_seq_show(struct seq_file *seq, void *v)
>   		seq_printf(seq, "\n");
>   	}
>   	spin_unlock(&mddev->lock);
> -	spin_lock(&all_mddevs_lock);
> +	spin_lock_irq(&all_mddevs_lock);
>   
>   	if (mddev == list_last_entry(&all_mddevs, struct mddev, all_mddevs))
>   		status_unused(seq);
> @@ -8987,7 +9017,7 @@ void md_do_sync(struct md_thread *thread)
>   	try_again:
>   		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
>   			goto skip;
> -		spin_lock(&all_mddevs_lock);
> +		spin_lock_irq(&all_mddevs_lock);
>   		list_for_each_entry(mddev2, &all_mddevs, all_mddevs) {
>   			if (test_bit(MD_DELETED, &mddev2->flags))
>   				continue;
> @@ -9022,7 +9052,7 @@ void md_do_sync(struct md_thread *thread)
>   							desc, mdname(mddev),
>   							mdname(mddev2));
>   					}
> -					spin_unlock(&all_mddevs_lock);
> +					spin_unlock_irq(&all_mddevs_lock);
>   
>   					if (signal_pending(current))
>   						flush_signals(current);
> @@ -9033,7 +9063,7 @@ void md_do_sync(struct md_thread *thread)
>   				finish_wait(&resync_wait, &wq);
>   			}
>   		}
> -		spin_unlock(&all_mddevs_lock);
> +		spin_unlock_irq(&all_mddevs_lock);
>   	} while (mddev->curr_resync < MD_RESYNC_DELAYED);
>   
>   	max_sectors = md_sync_max_sectors(mddev, action);
> @@ -9073,7 +9103,7 @@ void md_do_sync(struct md_thread *thread)
>   		mddev->curr_resync = MD_RESYNC_ACTIVE; /* no longer delayed */
>   	mddev->curr_resync_completed = j;
>   	sysfs_notify_dirent_safe(mddev->sysfs_completed);
> -	md_new_event();
> +	md_new_event(mddev, true);
>   	update_time = jiffies;
>   
>   	blk_start_plug(&plug);
> @@ -9145,7 +9175,7 @@ void md_do_sync(struct md_thread *thread)
>   			/* this is the earliest that rebuild will be
>   			 * visible in /proc/mdstat
>   			 */
> -			md_new_event();
> +			md_new_event(mddev, true);
>   
>   		if (last_check + window > io_sectors || j == max_sectors)
>   			continue;
> @@ -9411,7 +9441,7 @@ static int remove_and_add_spares(struct mddev *mddev,
>   			sysfs_link_rdev(mddev, rdev);
>   			if (!test_bit(Journal, &rdev->flags))
>   				spares++;
> -			md_new_event();
> +			md_new_event(mddev, true);
>   			set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
>   		}
>   	}
> @@ -9530,7 +9560,7 @@ static void md_start_sync(struct work_struct *ws)
>   		__mddev_resume(mddev, false);
>   	md_wakeup_thread(mddev->sync_thread);
>   	sysfs_notify_dirent_safe(mddev->sysfs_action);
> -	md_new_event();
> +	md_new_event(mddev, true);
>   	return;
>   
>   not_running:
> @@ -9782,7 +9812,7 @@ void md_reap_sync_thread(struct mddev *mddev)
>   	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
>   	sysfs_notify_dirent_safe(mddev->sysfs_completed);
>   	sysfs_notify_dirent_safe(mddev->sysfs_action);
> -	md_new_event();
> +	md_new_event(mddev, true);
>   	if (mddev->event_work.func)
>   		queue_work(md_misc_wq, &mddev->event_work);
>   	wake_up(&resync_wait);
> @@ -9863,11 +9893,11 @@ static int md_notify_reboot(struct notifier_block *this,
>   	struct mddev *mddev, *n;
>   	int need_delay = 0;
>   
> -	spin_lock(&all_mddevs_lock);
> +	spin_lock_irq(&all_mddevs_lock);
>   	list_for_each_entry_safe(mddev, n, &all_mddevs, all_mddevs) {
>   		if (!mddev_get(mddev))
>   			continue;
> -		spin_unlock(&all_mddevs_lock);
> +		spin_unlock_irq(&all_mddevs_lock);
>   		if (mddev_trylock(mddev)) {
>   			if (mddev->pers)
>   				__md_stop_writes(mddev);
> @@ -9877,9 +9907,9 @@ static int md_notify_reboot(struct notifier_block *this,
>   		}
>   		need_delay = 1;
>   		mddev_put(mddev);
> -		spin_lock(&all_mddevs_lock);
> +		spin_lock_irq(&all_mddevs_lock);
>   	}
> -	spin_unlock(&all_mddevs_lock);
> +	spin_unlock_irq(&all_mddevs_lock);
>   
>   	/*
>   	 * certain more exotic SCSI devices are known to be
> @@ -10230,11 +10260,11 @@ static __exit void md_exit(void)
>   	}
>   	remove_proc_entry("mdstat", NULL);
>   
> -	spin_lock(&all_mddevs_lock);
> +	spin_lock_irq(&all_mddevs_lock);
>   	list_for_each_entry_safe(mddev, n, &all_mddevs, all_mddevs) {
>   		if (!mddev_get(mddev))
>   			continue;
> -		spin_unlock(&all_mddevs_lock);
> +		spin_unlock_irq(&all_mddevs_lock);
>   		export_array(mddev);
>   		mddev->ctime = 0;
>   		mddev->hold_active = 0;
> @@ -10244,9 +10274,9 @@ static __exit void md_exit(void)
>   		 * destroy_workqueue() below will wait for that to complete.
>   		 */
>   		mddev_put(mddev);
> -		spin_lock(&all_mddevs_lock);
> +		spin_lock_irq(&all_mddevs_lock);
>   	}
> -	spin_unlock(&all_mddevs_lock);
> +	spin_unlock_irq(&all_mddevs_lock);
>   
>   	destroy_workqueue(md_misc_wq);
>   	destroy_workqueue(md_bitmap_wq);
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index a0d6827dced9..ab340618828c 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -582,6 +582,7 @@ struct mddev {
>   						*/
>   	struct work_struct flush_work;
>   	struct work_struct event_work;	/* used by dm to report failure event */
> +	struct work_struct uevent_work;
>   	mempool_t *serial_info_pool;
>   	void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
>   	struct md_cluster_info		*cluster_info;
> @@ -883,7 +884,7 @@ extern int md_super_wait(struct mddev *mddev);
>   extern int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
>   		struct page *page, blk_opf_t opf, bool metadata_op);
>   extern void md_do_sync(struct md_thread *thread);
> -extern void md_new_event(void);
> +extern void md_new_event(struct mddev *mddev, bool sync);
>   extern void md_allow_write(struct mddev *mddev);
>   extern void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev);
>   extern void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors);
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index 2a9c4ee982e0..f76571079845 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -4542,7 +4542,7 @@ static int raid10_start_reshape(struct mddev *mddev)
>   	set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
>   	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
>   	conf->reshape_checkpoint = jiffies;
> -	md_new_event();
> +	md_new_event(mddev, true);
>   	return 0;
>   
>   abort:
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index c14cf2410365..9da091b000d7 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -8525,7 +8525,7 @@ static int raid5_start_reshape(struct mddev *mddev)
>   	set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
>   	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
>   	conf->reshape_checkpoint = jiffies;
> -	md_new_event();
> +	md_new_event(mddev, true);
>   	return 0;
>   }
>