Kernel hang in blkg_destroy_all() when total blkg greater than
BLKG_DESTROY_BATCH_SIZE, because of not removing destroyed blkg in
blkg_list. So the size of blkg_list is same after destroying a
batch of blkg, and the infinite 'restart' occurs.
Since blkg should stay on the queue list until blkg_free_workfn(),
skip destroyed blkg when restart a new round, which will solve this
kernel hang issue and satisfy the previous will to restart.
Reported-by: Xiangfei Ma <[email protected]>
Tested-by: Xiangfei Ma <[email protected]>
Tested-by: Farrah Chen <[email protected]>
Signed-off-by: Yu Kuai <[email protected]>
Signed-off-by: Tao Su <[email protected]>
---
v2:
- change 'directly remove destroyed blkg' to 'skip destroyed blkg'
v1:
- https://lore.kernel.org/all/[email protected]/
block/blk-cgroup.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index bd50b55bdb61..75bad5d60c9f 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -528,6 +528,9 @@ static void blkg_destroy_all(struct gendisk *disk)
list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
struct blkcg *blkcg = blkg->blkcg;
+ if (hlist_unhashed(&blkg->blkcg_node))
+ continue;
+
spin_lock(&blkcg->lock);
blkg_destroy(blkg);
spin_unlock(&blkcg->lock);
--
2.34.1
Hi,
?? 2023/04/28 12:51, Tao Su д??:
> Kernel hang in blkg_destroy_all() when total blkg greater than
> BLKG_DESTROY_BATCH_SIZE, because of not removing destroyed blkg in
> blkg_list. So the size of blkg_list is same after destroying a
> batch of blkg, and the infinite 'restart' occurs.
>
> Since blkg should stay on the queue list until blkg_free_workfn(),
> skip destroyed blkg when restart a new round, which will solve this
> kernel hang issue and satisfy the previous will to restart.
Please add a fix tag:
Fixes: f1c006f1c685 ("blk-cgroup: synchronize pd_free_fn() from
blkg_free_workfn() and blkcg_deactivate_policy()")
>
> Reported-by: Xiangfei Ma <[email protected]>
> Tested-by: Xiangfei Ma <[email protected]>
> Tested-by: Farrah Chen <[email protected]>
> Signed-off-by: Yu Kuai <[email protected]>
You can remove this tag, and feel free to add:
Suggested-and-reviewed-by: Yu Kuai <[email protected]>
Thanks,
Kuai
> Signed-off-by: Tao Su <[email protected]>
> ---
> v2:
> - change 'directly remove destroyed blkg' to 'skip destroyed blkg'
>
> v1:
> - https://lore.kernel.org/all/[email protected]/
>
> block/blk-cgroup.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
> index bd50b55bdb61..75bad5d60c9f 100644
> --- a/block/blk-cgroup.c
> +++ b/block/blk-cgroup.c
> @@ -528,6 +528,9 @@ static void blkg_destroy_all(struct gendisk *disk)
> list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
> struct blkcg *blkcg = blkg->blkcg;
>
> + if (hlist_unhashed(&blkg->blkcg_node))
> + continue;
> +
> spin_lock(&blkcg->lock);
> blkg_destroy(blkg);
> spin_unlock(&blkcg->lock);
>
On Fri, Apr 28, 2023 at 02:12:06PM +0800, Yu Kuai wrote:
> Hi,
>
> 在 2023/04/28 12:51, Tao Su 写道:
> > Kernel hang in blkg_destroy_all() when total blkg greater than
> > BLKG_DESTROY_BATCH_SIZE, because of not removing destroyed blkg in
> > blkg_list. So the size of blkg_list is same after destroying a
> > batch of blkg, and the infinite 'restart' occurs.
> >
> > Since blkg should stay on the queue list until blkg_free_workfn(),
> > skip destroyed blkg when restart a new round, which will solve this
> > kernel hang issue and satisfy the previous will to restart.
>
> Please add a fix tag:
>
> Fixes: f1c006f1c685 ("blk-cgroup: synchronize pd_free_fn() from
> blkg_free_workfn() and blkcg_deactivate_policy()")
> >
> > Reported-by: Xiangfei Ma <[email protected]>
> > Tested-by: Xiangfei Ma <[email protected]>
> > Tested-by: Farrah Chen <[email protected]>
> > Signed-off-by: Yu Kuai <[email protected]>
>
> You can remove this tag, and feel free to add:
>
> Suggested-and-reviewed-by: Yu Kuai <[email protected]>
Got it, thanks!
Tao
>
> Thanks,
> Kuai
> > Signed-off-by: Tao Su <[email protected]>
> > ---
> > v2:
> > - change 'directly remove destroyed blkg' to 'skip destroyed blkg'
> >
> > v1:
> > - https://lore.kernel.org/all/[email protected]/
> >
> > block/blk-cgroup.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
> > index bd50b55bdb61..75bad5d60c9f 100644
> > --- a/block/blk-cgroup.c
> > +++ b/block/blk-cgroup.c
> > @@ -528,6 +528,9 @@ static void blkg_destroy_all(struct gendisk *disk)
> > list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
> > struct blkcg *blkcg = blkg->blkcg;
> > + if (hlist_unhashed(&blkg->blkcg_node))
> > + continue;
> > +
> > spin_lock(&blkcg->lock);
> > blkg_destroy(blkg);
> > spin_unlock(&blkcg->lock);
> >
>
On Fri, 28 Apr 2023 12:51:49 +0800, Tao Su wrote:
> Kernel hang in blkg_destroy_all() when total blkg greater than
> BLKG_DESTROY_BATCH_SIZE, because of not removing destroyed blkg in
> blkg_list. So the size of blkg_list is same after destroying a
> batch of blkg, and the infinite 'restart' occurs.
>
> Since blkg should stay on the queue list until blkg_free_workfn(),
> skip destroyed blkg when restart a new round, which will solve this
> kernel hang issue and satisfy the previous will to restart.
>
> [...]
Applied, thanks!
[1/1] block: Skip destroyed blkg when restart in blkg_destroy_all()
commit: 8176080d59e6d4ff9fc97ae534063073b4f7a715
Best regards,
--
Jens Axboe
On Fri, Apr 28, 2023 at 11:24:20AM -0600, Jens Axboe wrote:
>
> On Fri, 28 Apr 2023 12:51:49 +0800, Tao Su wrote:
> > Kernel hang in blkg_destroy_all() when total blkg greater than
> > BLKG_DESTROY_BATCH_SIZE, because of not removing destroyed blkg in
> > blkg_list. So the size of blkg_list is same after destroying a
> > batch of blkg, and the infinite 'restart' occurs.
> >
> > Since blkg should stay on the queue list until blkg_free_workfn(),
> > skip destroyed blkg when restart a new round, which will solve this
> > kernel hang issue and satisfy the previous will to restart.
> >
> > [...]
>
> Applied, thanks!
Axboe, thanks!
Tao
>
> [1/1] block: Skip destroyed blkg when restart in blkg_destroy_all()
> commit: 8176080d59e6d4ff9fc97ae534063073b4f7a715
>
> Best regards,
> --
> Jens Axboe
>
>
>