* Re: [PATCH] blk-mq: add missing call to srcu_barrier() in blk_mq_free_tag_set()
2026-08-12 6:05 ` [PATCH] blk-mq: add missing call to srcu_barrier() in blk_mq_free_tag_set() Marek Szyprowski
@ 2026-08-12 14:07 ` Paul E. McKenney
2026-08-15 1:34 ` Zqiang
1 sibling, 0 replies; 3+ messages in thread
From: Paul E. McKenney @ 2026-08-12 14:07 UTC (permalink / raw)
To: Marek Szyprowski; +Cc: linux-block, linux-kernel, Jens Axboe, Zqiang
On Wed, Aug 12, 2026 at 08:05:08AM +0200, Marek Szyprowski wrote:
> Commit 05c3e88488ed ("srcu: Queue sdp->work when the delay timer is
> successfully deleted") added a check in cleanup_srcu_struct() if the
> call to srcu_barrier() has been made before calling it, which
> revealed a missing call to srcu_barrier() before calling
> cleanup_srcu_struct(set->srcu). Fix this.
>
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
> ---
> This fixes the following issue observed recently in linux-next:
> ------------[ cut here ]------------
> WARNING: kernel/rcu/srcutree.c:706 at cleanup_srcu_struct+0x194/0x3d4, CPU#1: kworker/1:2/156
> Modules linked in: s5p_mfc exynos_gsc s5p_jpeg videobuf2_dma_contig v4l2_mem2mem videobuf2_memops videobuf2_v4l2 videobuf2_common videodev mc
> CPU: 1 UID: 0 PID: 156 Comm: kworker/1:2 Not tainted 7.2.0-rc3-00006-g05c3e88488ed-dirty #13430 PREEMPT
> Hardware name: Samsung Exynos (Flattened Device Tree)
> Workqueue: usb_hub_wq hub_event
> Call trace:
> unwind_backtrace from show_stack+0x10/0x14
> show_stack from dump_stack_lvl+0x6c/0x8c
> dump_stack_lvl from __warn+0x90/0x204
> __warn from warn_slowpath_fmt+0x1b4/0x1bc
> warn_slowpath_fmt from cleanup_srcu_struct+0x194/0x3d4
> cleanup_srcu_struct from blk_mq_free_tag_set+0x138/0x158
> blk_mq_free_tag_set from scsi_mq_free_tags+0x10/0x1c
> scsi_mq_free_tags from scsi_remove_host+0x14c/0x170
> scsi_remove_host from uas_disconnect+0x70/0x84
> uas_disconnect from usb_unbind_interface+0x78/0x2b4
> usb_unbind_interface from device_release_driver_internal+0x194/0x208
> device_release_driver_internal from bus_remove_device+0xf8/0x1c8
> bus_remove_device from device_del+0x138/0x3b0
> device_del from usb_disable_device+0xec/0x22c
> usb_disable_device from usb_disconnect+0xf8/0x2bc
> usb_disconnect from hub_event+0x9a8/0x1c3c
> hub_event from process_one_work+0x258/0x798
> process_one_work from worker_thread+0x1bc/0x3cc
> worker_thread from kthread+0x138/0x16c
> kthread from ret_from_fork+0x14/0x28
> Exception stack(0xf0dfdfb0 to 0xf0dfdff8)
> dfa0: 00000000 00000000 00000000 00000000
> dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
> irq event stamp: 23097
> hardirqs last enabled at (23109): [<c0100bf8>] __irq_svc+0xb8/0xd0
> hardirqs last disabled at (23118): [<c0100b94>] __irq_svc+0x54/0xd0
> softirqs last enabled at (23094): [<c013ef54>] handle_softirqs+0x32c/0x58c
> softirqs last disabled at (23065): [<c013f360>] __irq_exit_rcu+0x144/0x1f0
> ---[ end trace 0000000000000000 ]---
> ---
> block/blk-mq.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 2c850330a32b..a26a11c73ee3 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -4975,6 +4975,7 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
> srcu_barrier(&set->tags_srcu);
> cleanup_srcu_struct(&set->tags_srcu);
> if (set->flags & BLK_MQ_F_BLOCKING) {
> + srcu_barrier(set->srcu);
> cleanup_srcu_struct(set->srcu);
> kfree(set->srcu);
> }
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] blk-mq: add missing call to srcu_barrier() in blk_mq_free_tag_set()
2026-08-12 6:05 ` [PATCH] blk-mq: add missing call to srcu_barrier() in blk_mq_free_tag_set() Marek Szyprowski
2026-08-12 14:07 ` Paul E. McKenney
@ 2026-08-15 1:34 ` Zqiang
1 sibling, 0 replies; 3+ messages in thread
From: Zqiang @ 2026-08-15 1:34 UTC (permalink / raw)
To: Marek Szyprowski, linux-block, linux-kernel
Cc: Marek Szyprowski, Jens Axboe, Paul E . McKenney
>
> Commit 05c3e88488ed ("srcu: Queue sdp->work when the delay timer is
> successfully deleted") added a check in cleanup_srcu_struct() if the
> call to srcu_barrier() has been made before calling it, which
> revealed a missing call to srcu_barrier() before calling
> cleanup_srcu_struct(set->srcu). Fix this.
This warnings should be fix in cleanup_srcu_struct().
https://lore.kernel.org/oe-lkp/202608060833.bce92909-lkp@intel.com/
and the set->srcu only be used by synchronize_srcu(), there are no
call_srcu(), so the srcu_barrier() should not be invoke before cleanup
Thanks
Zqiang
>
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
> This fixes the following issue observed recently in linux-next:
> ------------[ cut here ]------------
> WARNING: kernel/rcu/srcutree.c:706 at cleanup_srcu_struct+0x194/0x3d4, CPU#1: kworker/1:2/156
> Modules linked in: s5p_mfc exynos_gsc s5p_jpeg videobuf2_dma_contig v4l2_mem2mem videobuf2_memops videobuf2_v4l2 videobuf2_common videodev mc
> CPU: 1 UID: 0 PID: 156 Comm: kworker/1:2 Not tainted 7.2.0-rc3-00006-g05c3e88488ed-dirty #13430 PREEMPT
> Hardware name: Samsung Exynos (Flattened Device Tree)
> Workqueue: usb_hub_wq hub_event
> Call trace:
> unwind_backtrace from show_stack+0x10/0x14
> show_stack from dump_stack_lvl+0x6c/0x8c
> dump_stack_lvl from __warn+0x90/0x204
> __warn from warn_slowpath_fmt+0x1b4/0x1bc
> warn_slowpath_fmt from cleanup_srcu_struct+0x194/0x3d4
> cleanup_srcu_struct from blk_mq_free_tag_set+0x138/0x158
> blk_mq_free_tag_set from scsi_mq_free_tags+0x10/0x1c
> scsi_mq_free_tags from scsi_remove_host+0x14c/0x170
> scsi_remove_host from uas_disconnect+0x70/0x84
> uas_disconnect from usb_unbind_interface+0x78/0x2b4
> usb_unbind_interface from device_release_driver_internal+0x194/0x208
> device_release_driver_internal from bus_remove_device+0xf8/0x1c8
> bus_remove_device from device_del+0x138/0x3b0
> device_del from usb_disable_device+0xec/0x22c
> usb_disable_device from usb_disconnect+0xf8/0x2bc
> usb_disconnect from hub_event+0x9a8/0x1c3c
> hub_event from process_one_work+0x258/0x798
> process_one_work from worker_thread+0x1bc/0x3cc
> worker_thread from kthread+0x138/0x16c
> kthread from ret_from_fork+0x14/0x28
> Exception stack(0xf0dfdfb0 to 0xf0dfdff8)
> dfa0: 00000000 00000000 00000000 00000000
> dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
> irq event stamp: 23097
> hardirqs last enabled at (23109): [<c0100bf8>] __irq_svc+0xb8/0xd0
> hardirqs last disabled at (23118): [<c0100b94>] __irq_svc+0x54/0xd0
> softirqs last enabled at (23094): [<c013ef54>] handle_softirqs+0x32c/0x58c
> softirqs last disabled at (23065): [<c013f360>] __irq_exit_rcu+0x144/0x1f0
> ---[ end trace 0000000000000000 ]---
> ---
> block/blk-mq.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 2c850330a32b..a26a11c73ee3 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -4975,6 +4975,7 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
> srcu_barrier(&set->tags_srcu);
> cleanup_srcu_struct(&set->tags_srcu);
> if (set->flags & BLK_MQ_F_BLOCKING) {
> + srcu_barrier(set->srcu);
> cleanup_srcu_struct(set->srcu);
> kfree(set->srcu);
> }
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 3+ messages in thread