| Message ID | 20180430195649.17445-1-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Daniel, On Mon, Apr 30, 2018 at 09:56:49PM +0200, Daniel Vetter wrote: > At least trackpoint_disconnect wants to remove some sysfs files, and > we can't remove sysfs files while holding psmouse_mutex: > > ====================================================== > WARNING: possible circular locking dependency detected > 4.16.0-rc5-g613eb885b69e-drmtip_1+ #1 Tainted: G U > ------------------------------------------------------ > kworker/0:3/102 is trying to acquire lock: > (kn->count#130){++++}, at: [<000000009679748b>] kernfs_remove_by_name_ns+0x3b/0x80 > > but task is already holding lock: > (psmouse_mutex){+.+.}, at: [<0000000014f44bcc>] psmouse_disconnect+0x62/0x160 > > which lock already depends on the new lock. > > the existing dependency chain (in reverse order) is: > > -> #1 (psmouse_mutex){+.+.}: > psmouse_attr_set_helper+0x28/0x140 > kernfs_fop_write+0xfe/0x180 > __vfs_write+0x1e/0x130 > vfs_write+0xbd/0x1b0 > SyS_write+0x40/0xa0 > do_syscall_64+0x65/0x1a0 > entry_SYSCALL_64_after_hwframe+0x42/0xb7 > > -> #0 (kn->count#130){++++}: > __kernfs_remove+0x243/0x2b0 > kernfs_remove_by_name_ns+0x3b/0x80 > remove_files.isra.0+0x2b/0x60 > sysfs_remove_group+0x38/0x80 > sysfs_remove_groups+0x24/0x40 > trackpoint_disconnect+0x2c/0x50 > psmouse_disconnect+0x8f/0x160 > serio_disconnect_driver+0x28/0x40 > serio_driver_remove+0xc/0x10 > device_release_driver_internal+0x15b/0x230 > serio_handle_event+0x1c8/0x260 > process_one_work+0x215/0x620 > worker_thread+0x48/0x3a0 > kthread+0xfb/0x130 > ret_from_fork+0x3a/0x50 > > other info that might help us debug this: > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(psmouse_mutex); > lock(kn->count#130); > lock(psmouse_mutex); > lock(kn->count#130); > > *** DEADLOCK *** > > 6 locks held by kworker/0:3/102: > #0: ((wq_completion)"events_long"){+.+.}, at: [<000000002e408bfa>] process_one_work+0x191/0x620 > #1: (serio_event_work){+.+.}, at: [<000000002e408bfa>] process_one_work+0x191/0x620 > #2: (serio_mutex){+.+.}, at: [<00000000c8a49847>] serio_handle_event+0x23/0x260 > #3: (&dev->mutex){....}, at: [<00000000b55eee75>] device_release_driver_internal+0x2f/0x230 > #4: (&serio->drv_mutex){+.+.}, at: [<000000009719f997>] serio_disconnect_driver+0x16/0x40 > #5: (psmouse_mutex){+.+.}, at: [<0000000014f44bcc>] psmouse_disconnect+0x62/0x160 > > stack backtrace: > CPU: 0 PID: 102 Comm: kworker/0:3 Tainted: G U 4.16.0-rc5-g613eb885b69e-drmtip_1+ #1 > Hardware name: LENOVO 74591P0/74591P0, BIOS 6DET28WW (1.05 ) 07/30/2008 > Workqueue: events_long serio_handle_event > Call Trace: > dump_stack+0x5f/0x86 > print_circular_bug.isra.18+0x1d0/0x2c0 > __lock_acquire+0x14ae/0x1b60 > ? kernfs_remove_by_name_ns+0x20/0x80 > ? lock_acquire+0xaf/0x200 > lock_acquire+0xaf/0x200 > ? kernfs_remove_by_name_ns+0x3b/0x80 > __kernfs_remove+0x243/0x2b0 > ? kernfs_remove_by_name_ns+0x3b/0x80 > ? kernfs_name_hash+0xd/0x70 > ? kernfs_find_ns+0x7e/0x100 > kernfs_remove_by_name_ns+0x3b/0x80 > remove_files.isra.0+0x2b/0x60 > sysfs_remove_group+0x38/0x80 > sysfs_remove_groups+0x24/0x40 > trackpoint_disconnect+0x2c/0x50 > psmouse_disconnect+0x8f/0x160 > serio_disconnect_driver+0x28/0x40 > serio_driver_remove+0xc/0x10 > device_release_driver_internal+0x15b/0x230 > serio_handle_event+0x1c8/0x260 > process_one_work+0x215/0x620 > worker_thread+0x48/0x3a0 > ? _raw_spin_unlock_irqrestore+0x4c/0x60 > kthread+0xfb/0x130 > ? process_one_work+0x620/0x620 > ? _kthread_create_on_node+0x30/0x30 > ret_from_fork+0x3a/0x50 > > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> > Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com> > Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > Cc: Arvind Yadav <arvind.yadav.cs@gmail.com> > Cc: Stephen Lyons <slysven@virginmedia.com> > Cc: linux-input@vger.kernel.org > --- > drivers/input/mouse/psmouse-base.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c > index 8900c3166ebf..06ccd8e22f3c 100644 > --- a/drivers/input/mouse/psmouse-base.c > +++ b/drivers/input/mouse/psmouse-base.c > @@ -1484,8 +1484,10 @@ static void psmouse_disconnect(struct serio *serio) > psmouse_deactivate(parent); > } > > + mutex_unlock(&psmouse_mutex); > if (psmouse->disconnect) > psmouse->disconnect(psmouse); > + mutex_lock(&psmouse_mutex); Why do you think it is proper to drop this mutex? It is introduced for a reason. I think the trace you are seeing is due to: commit 988cd7afb3f37598891ca70b4c6eb914c338c46a Author: Tejun Heo <tj@kernel.org> Date: Mon Feb 3 14:02:58 2014 -0500 kernfs: remove kernfs_addrm_cxt where we started taking kernfs_mutex when adding/removing sysfs files. Ultimately I think we may have to change switching protocol to a work item to be done asynchronously from writing to sysfs attribute. Thanks.
On Mon, Apr 30, 2018 at 11:17 PM, Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote: > Hi Daniel, > > On Mon, Apr 30, 2018 at 09:56:49PM +0200, Daniel Vetter wrote: >> At least trackpoint_disconnect wants to remove some sysfs files, and >> we can't remove sysfs files while holding psmouse_mutex: >> >> ====================================================== >> WARNING: possible circular locking dependency detected >> 4.16.0-rc5-g613eb885b69e-drmtip_1+ #1 Tainted: G U >> ------------------------------------------------------ >> kworker/0:3/102 is trying to acquire lock: >> (kn->count#130){++++}, at: [<000000009679748b>] kernfs_remove_by_name_ns+0x3b/0x80 >> >> but task is already holding lock: >> (psmouse_mutex){+.+.}, at: [<0000000014f44bcc>] psmouse_disconnect+0x62/0x160 >> >> which lock already depends on the new lock. >> >> the existing dependency chain (in reverse order) is: >> >> -> #1 (psmouse_mutex){+.+.}: >> psmouse_attr_set_helper+0x28/0x140 >> kernfs_fop_write+0xfe/0x180 >> __vfs_write+0x1e/0x130 >> vfs_write+0xbd/0x1b0 >> SyS_write+0x40/0xa0 >> do_syscall_64+0x65/0x1a0 >> entry_SYSCALL_64_after_hwframe+0x42/0xb7 >> >> -> #0 (kn->count#130){++++}: >> __kernfs_remove+0x243/0x2b0 >> kernfs_remove_by_name_ns+0x3b/0x80 >> remove_files.isra.0+0x2b/0x60 >> sysfs_remove_group+0x38/0x80 >> sysfs_remove_groups+0x24/0x40 >> trackpoint_disconnect+0x2c/0x50 >> psmouse_disconnect+0x8f/0x160 >> serio_disconnect_driver+0x28/0x40 >> serio_driver_remove+0xc/0x10 >> device_release_driver_internal+0x15b/0x230 >> serio_handle_event+0x1c8/0x260 >> process_one_work+0x215/0x620 >> worker_thread+0x48/0x3a0 >> kthread+0xfb/0x130 >> ret_from_fork+0x3a/0x50 >> >> other info that might help us debug this: >> >> Possible unsafe locking scenario: >> >> CPU0 CPU1 >> ---- ---- >> lock(psmouse_mutex); >> lock(kn->count#130); >> lock(psmouse_mutex); >> lock(kn->count#130); >> >> *** DEADLOCK *** >> >> 6 locks held by kworker/0:3/102: >> #0: ((wq_completion)"events_long"){+.+.}, at: [<000000002e408bfa>] process_one_work+0x191/0x620 >> #1: (serio_event_work){+.+.}, at: [<000000002e408bfa>] process_one_work+0x191/0x620 >> #2: (serio_mutex){+.+.}, at: [<00000000c8a49847>] serio_handle_event+0x23/0x260 >> #3: (&dev->mutex){....}, at: [<00000000b55eee75>] device_release_driver_internal+0x2f/0x230 >> #4: (&serio->drv_mutex){+.+.}, at: [<000000009719f997>] serio_disconnect_driver+0x16/0x40 >> #5: (psmouse_mutex){+.+.}, at: [<0000000014f44bcc>] psmouse_disconnect+0x62/0x160 >> >> stack backtrace: >> CPU: 0 PID: 102 Comm: kworker/0:3 Tainted: G U 4.16.0-rc5-g613eb885b69e-drmtip_1+ #1 >> Hardware name: LENOVO 74591P0/74591P0, BIOS 6DET28WW (1.05 ) 07/30/2008 >> Workqueue: events_long serio_handle_event >> Call Trace: >> dump_stack+0x5f/0x86 >> print_circular_bug.isra.18+0x1d0/0x2c0 >> __lock_acquire+0x14ae/0x1b60 >> ? kernfs_remove_by_name_ns+0x20/0x80 >> ? lock_acquire+0xaf/0x200 >> lock_acquire+0xaf/0x200 >> ? kernfs_remove_by_name_ns+0x3b/0x80 >> __kernfs_remove+0x243/0x2b0 >> ? kernfs_remove_by_name_ns+0x3b/0x80 >> ? kernfs_name_hash+0xd/0x70 >> ? kernfs_find_ns+0x7e/0x100 >> kernfs_remove_by_name_ns+0x3b/0x80 >> remove_files.isra.0+0x2b/0x60 >> sysfs_remove_group+0x38/0x80 >> sysfs_remove_groups+0x24/0x40 >> trackpoint_disconnect+0x2c/0x50 >> psmouse_disconnect+0x8f/0x160 >> serio_disconnect_driver+0x28/0x40 >> serio_driver_remove+0xc/0x10 >> device_release_driver_internal+0x15b/0x230 >> serio_handle_event+0x1c8/0x260 >> process_one_work+0x215/0x620 >> worker_thread+0x48/0x3a0 >> ? _raw_spin_unlock_irqrestore+0x4c/0x60 >> kthread+0xfb/0x130 >> ? process_one_work+0x620/0x620 >> ? _kthread_create_on_node+0x30/0x30 >> ret_from_fork+0x3a/0x50 >> >> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> >> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com> >> Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com> >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> >> Cc: Arvind Yadav <arvind.yadav.cs@gmail.com> >> Cc: Stephen Lyons <slysven@virginmedia.com> >> Cc: linux-input@vger.kernel.org >> --- >> drivers/input/mouse/psmouse-base.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c >> index 8900c3166ebf..06ccd8e22f3c 100644 >> --- a/drivers/input/mouse/psmouse-base.c >> +++ b/drivers/input/mouse/psmouse-base.c >> @@ -1484,8 +1484,10 @@ static void psmouse_disconnect(struct serio *serio) >> psmouse_deactivate(parent); >> } >> >> + mutex_unlock(&psmouse_mutex); >> if (psmouse->disconnect) >> psmouse->disconnect(psmouse); >> + mutex_lock(&psmouse_mutex); > > Why do you think it is proper to drop this mutex? It is introduced for a > reason. > > I think the trace you are seeing is due to: > > commit 988cd7afb3f37598891ca70b4c6eb914c338c46a > Author: Tejun Heo <tj@kernel.org> > Date: Mon Feb 3 14:02:58 2014 -0500 > > kernfs: remove kernfs_addrm_cxt > > where we started taking kernfs_mutex when adding/removing sysfs files. > Ultimately I think we may have to change switching protocol to a work > item to be done asynchronously from writing to sysfs attribute. Well "holding a lock while adding/removing sysfs files and holding the same lock from sysfs read/write callbacks" is a classic deadlock. I've made lockdep shut up about it, I have no idea how to fix it properly. kernfs switching it's locking doesn't change anything here. Generally the fix is to untangle the locking: You need 1 set of locks to protect the datastructures exposed through sysfs, and another thing (maybe that's provided by serio already, I have no idea) to make sure you're ordering connect/disconnect handling correct and there's not concurrent calls to this hooks. Assuming serio does give that guarantee then there's no need to hold the lock while unregistering the sysfs files (we could perhaps push the lock dropping down into trackpoint_disconnect, but that's less maintainable imo since it's not obvious in psmouse_disconnect what's going on), and my patch is correct. But I didn't do a full locking audit of what exactly serio guarantees, and what exactly psmouse_mutex needs to protect (and where psmouse_mutex is only held because it's convenient). -Daniel
On Wed, May 2, 2018 at 11:06 AM Daniel Vetter <daniel.vetter@ffwll.ch> wrote: > > On Mon, Apr 30, 2018 at 11:17 PM, Dmitry Torokhov > <dmitry.torokhov@gmail.com> wrote: > > Hi Daniel, > > > > On Mon, Apr 30, 2018 at 09:56:49PM +0200, Daniel Vetter wrote: > >> At least trackpoint_disconnect wants to remove some sysfs files, and > >> we can't remove sysfs files while holding psmouse_mutex: > >> > >> ====================================================== > >> WARNING: possible circular locking dependency detected > >> 4.16.0-rc5-g613eb885b69e-drmtip_1+ #1 Tainted: G U > >> ------------------------------------------------------ > >> kworker/0:3/102 is trying to acquire lock: > >> (kn->count#130){++++}, at: [<000000009679748b>] kernfs_remove_by_name_ns+0x3b/0x80 > >> > >> but task is already holding lock: > >> (psmouse_mutex){+.+.}, at: [<0000000014f44bcc>] psmouse_disconnect+0x62/0x160 > >> > >> which lock already depends on the new lock. > >> > >> the existing dependency chain (in reverse order) is: > >> > >> -> #1 (psmouse_mutex){+.+.}: > >> psmouse_attr_set_helper+0x28/0x140 > >> kernfs_fop_write+0xfe/0x180 > >> __vfs_write+0x1e/0x130 > >> vfs_write+0xbd/0x1b0 > >> SyS_write+0x40/0xa0 > >> do_syscall_64+0x65/0x1a0 > >> entry_SYSCALL_64_after_hwframe+0x42/0xb7 > >> > >> -> #0 (kn->count#130){++++}: > >> __kernfs_remove+0x243/0x2b0 > >> kernfs_remove_by_name_ns+0x3b/0x80 > >> remove_files.isra.0+0x2b/0x60 > >> sysfs_remove_group+0x38/0x80 > >> sysfs_remove_groups+0x24/0x40 > >> trackpoint_disconnect+0x2c/0x50 > >> psmouse_disconnect+0x8f/0x160 > >> serio_disconnect_driver+0x28/0x40 > >> serio_driver_remove+0xc/0x10 > >> device_release_driver_internal+0x15b/0x230 > >> serio_handle_event+0x1c8/0x260 > >> process_one_work+0x215/0x620 > >> worker_thread+0x48/0x3a0 > >> kthread+0xfb/0x130 > >> ret_from_fork+0x3a/0x50 > >> > >> other info that might help us debug this: > >> > >> Possible unsafe locking scenario: > >> > >> CPU0 CPU1 > >> ---- ---- > >> lock(psmouse_mutex); > >> lock(kn->count#130); > >> lock(psmouse_mutex); > >> lock(kn->count#130); > >> > >> *** DEADLOCK *** > >> > >> 6 locks held by kworker/0:3/102: > >> #0: ((wq_completion)"events_long"){+.+.}, at: [<000000002e408bfa>] process_one_work+0x191/0x620 > >> #1: (serio_event_work){+.+.}, at: [<000000002e408bfa>] process_one_work+0x191/0x620 > >> #2: (serio_mutex){+.+.}, at: [<00000000c8a49847>] serio_handle_event+0x23/0x260 > >> #3: (&dev->mutex){....}, at: [<00000000b55eee75>] device_release_driver_internal+0x2f/0x230 > >> #4: (&serio->drv_mutex){+.+.}, at: [<000000009719f997>] serio_disconnect_driver+0x16/0x40 > >> #5: (psmouse_mutex){+.+.}, at: [<0000000014f44bcc>] psmouse_disconnect+0x62/0x160 > >> > >> stack backtrace: > >> CPU: 0 PID: 102 Comm: kworker/0:3 Tainted: G U 4.16.0-rc5-g613eb885b69e-drmtip_1+ #1 > >> Hardware name: LENOVO 74591P0/74591P0, BIOS 6DET28WW (1.05 ) 07/30/2008 > >> Workqueue: events_long serio_handle_event > >> Call Trace: > >> dump_stack+0x5f/0x86 > >> print_circular_bug.isra.18+0x1d0/0x2c0 > >> __lock_acquire+0x14ae/0x1b60 > >> ? kernfs_remove_by_name_ns+0x20/0x80 > >> ? lock_acquire+0xaf/0x200 > >> lock_acquire+0xaf/0x200 > >> ? kernfs_remove_by_name_ns+0x3b/0x80 > >> __kernfs_remove+0x243/0x2b0 > >> ? kernfs_remove_by_name_ns+0x3b/0x80 > >> ? kernfs_name_hash+0xd/0x70 > >> ? kernfs_find_ns+0x7e/0x100 > >> kernfs_remove_by_name_ns+0x3b/0x80 > >> remove_files.isra.0+0x2b/0x60 > >> sysfs_remove_group+0x38/0x80 > >> sysfs_remove_groups+0x24/0x40 > >> trackpoint_disconnect+0x2c/0x50 > >> psmouse_disconnect+0x8f/0x160 > >> serio_disconnect_driver+0x28/0x40 > >> serio_driver_remove+0xc/0x10 > >> device_release_driver_internal+0x15b/0x230 > >> serio_handle_event+0x1c8/0x260 > >> process_one_work+0x215/0x620 > >> worker_thread+0x48/0x3a0 > >> ? _raw_spin_unlock_irqrestore+0x4c/0x60 > >> kthread+0xfb/0x130 > >> ? process_one_work+0x620/0x620 > >> ? _kthread_create_on_node+0x30/0x30 > >> ret_from_fork+0x3a/0x50 > >> > >> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> > >> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com> > >> Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com> > >> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > >> Cc: Arvind Yadav <arvind.yadav.cs@gmail.com> > >> Cc: Stephen Lyons <slysven@virginmedia.com> > >> Cc: linux-input@vger.kernel.org > >> --- > >> drivers/input/mouse/psmouse-base.c | 2 ++ > >> 1 file changed, 2 insertions(+) > >> > >> diff --git a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c > >> index 8900c3166ebf..06ccd8e22f3c 100644 > >> --- a/drivers/input/mouse/psmouse-base.c > >> +++ b/drivers/input/mouse/psmouse-base.c > >> @@ -1484,8 +1484,10 @@ static void psmouse_disconnect(struct serio *serio) > >> psmouse_deactivate(parent); > >> } > >> > >> + mutex_unlock(&psmouse_mutex); > >> if (psmouse->disconnect) > >> psmouse->disconnect(psmouse); > >> + mutex_lock(&psmouse_mutex); > > > > Why do you think it is proper to drop this mutex? It is introduced for a > > reason. > > > > I think the trace you are seeing is due to: > > > > commit 988cd7afb3f37598891ca70b4c6eb914c338c46a > > Author: Tejun Heo <tj@kernel.org> > > Date: Mon Feb 3 14:02:58 2014 -0500 > > > > kernfs: remove kernfs_addrm_cxt > > > > where we started taking kernfs_mutex when adding/removing sysfs files. > > Ultimately I think we may have to change switching protocol to a work > > item to be done asynchronously from writing to sysfs attribute. > > Well "holding a lock while adding/removing sysfs files and holding the > same lock from sysfs read/write callbacks" is a classic deadlock. I've > made lockdep shut up about it, I have no idea how to fix it properly. > kernfs switching it's locking doesn't change anything here. > > Generally the fix is to untangle the locking: You need 1 set of locks > to protect the datastructures exposed through sysfs, and another thing > (maybe that's provided by serio already, I have no idea) to make sure > you're ordering connect/disconnect handling correct and there's not > concurrent calls to this hooks. Assuming serio does give that > guarantee then there's no need to hold the lock while unregistering > the sysfs files (we could perhaps push the lock dropping down into > trackpoint_disconnect, but that's less maintainable imo since it's not > obvious in psmouse_disconnect what's going on), and my patch is > correct. > > But I didn't do a full locking audit of what exactly serio guarantees, > and what exactly psmouse_mutex needs to protect (and where > psmouse_mutex is only held because it's convenient). Ping? Just noticed that I still have this bugfix hanging around. bugfix as in "make lockdep more useful", not necessarily fixing the locking here properly. I guess I could respin to add a FIXME comment, but not sure how useful that would be. -Daniel
====================================================== WARNING: possible circular locking dependency detected 4.16.0-rc5-g613eb885b69e-drmtip_1+ #1 Tainted: G U ------------------------------------------------------ kworker/0:3/102 is trying to acquire lock: (kn->count#130){++++}, at: [<000000009679748b>] kernfs_remove_by_name_ns+0x3b/0x80 but task is already holding lock: (psmouse_mutex){+.+.}, at: [<0000000014f44bcc>] psmouse_disconnect+0x62/0x160 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (psmouse_mutex){+.+.}: psmouse_attr_set_helper+0x28/0x140 kernfs_fop_write+0xfe/0x180 __vfs_write+0x1e/0x130 vfs_write+0xbd/0x1b0 SyS_write+0x40/0xa0 do_syscall_64+0x65/0x1a0 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (kn->count#130){++++}: __kernfs_remove+0x243/0x2b0 kernfs_remove_by_name_ns+0x3b/0x80 remove_files.isra.0+0x2b/0x60 sysfs_remove_group+0x38/0x80 sysfs_remove_groups+0x24/0x40 trackpoint_disconnect+0x2c/0x50 psmouse_disconnect+0x8f/0x160 serio_disconnect_driver+0x28/0x40 serio_driver_remove+0xc/0x10 device_release_driver_internal+0x15b/0x230 serio_handle_event+0x1c8/0x260 process_one_work+0x215/0x620 worker_thread+0x48/0x3a0 kthread+0xfb/0x130 ret_from_fork+0x3a/0x50 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(psmouse_mutex); lock(kn->count#130); lock(psmouse_mutex); lock(kn->count#130); *** DEADLOCK *** 6 locks held by kworker/0:3/102: #0: ((wq_completion)"events_long"){+.+.}, at: [<000000002e408bfa>] process_one_work+0x191/0x620 #1: (serio_event_work){+.+.}, at: [<000000002e408bfa>] process_one_work+0x191/0x620 #2: (serio_mutex){+.+.}, at: [<00000000c8a49847>] serio_handle_event+0x23/0x260 #3: (&dev->mutex){....}, at: [<00000000b55eee75>] device_release_driver_internal+0x2f/0x230 #4: (&serio->drv_mutex){+.+.}, at: [<000000009719f997>] serio_disconnect_driver+0x16/0x40 #5: (psmouse_mutex){+.+.}, at: [<0000000014f44bcc>] psmouse_disconnect+0x62/0x160 stack backtrace: CPU: 0 PID: 102 Comm: kworker/0:3 Tainted: G U 4.16.0-rc5-g613eb885b69e-drmtip_1+ #1 Hardware name: LENOVO 74591P0/74591P0, BIOS 6DET28WW (1.05 ) 07/30/2008 Workqueue: events_long serio_handle_event Call Trace: dump_stack+0x5f/0x86 print_circular_bug.isra.18+0x1d0/0x2c0 __lock_acquire+0x14ae/0x1b60 ? kernfs_remove_by_name_ns+0x20/0x80 ? lock_acquire+0xaf/0x200 lock_acquire+0xaf/0x200 ? kernfs_remove_by_name_ns+0x3b/0x80 __kernfs_remove+0x243/0x2b0 ? kernfs_remove_by_name_ns+0x3b/0x80 ? kernfs_name_hash+0xd/0x70 ? kernfs_find_ns+0x7e/0x100 kernfs_remove_by_name_ns+0x3b/0x80 remove_files.isra.0+0x2b/0x60 sysfs_remove_group+0x38/0x80 sysfs_remove_groups+0x24/0x40 trackpoint_disconnect+0x2c/0x50 psmouse_disconnect+0x8f/0x160 serio_disconnect_driver+0x28/0x40 serio_driver_remove+0xc/0x10 device_release_driver_internal+0x15b/0x230 serio_handle_event+0x1c8/0x260 process_one_work+0x215/0x620 worker_thread+0x48/0x3a0 ? _raw_spin_unlock_irqrestore+0x4c/0x60 kthread+0xfb/0x130 ? process_one_work+0x620/0x620 ? _kthread_create_on_node+0x30/0x30 ret_from_fork+0x3a/0x50 Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com> Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Arvind Yadav <arvind.yadav.cs@gmail.com> Cc: Stephen Lyons <slysven@virginmedia.com> Cc: linux-input@vger.kernel.org --- drivers/input/mouse/psmouse-base.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c index 8900c3166ebf..06ccd8e22f3c 100644 --- a/drivers/input/mouse/psmouse-base.c +++ b/drivers/input/mouse/psmouse-base.c @@ -1484,8 +1484,10 @@ static void psmouse_disconnect(struct serio *serio) psmouse_deactivate(parent); } + mutex_unlock(&psmouse_mutex); if (psmouse->disconnect) psmouse->disconnect(psmouse); + mutex_lock(&psmouse_mutex); if (parent && parent->pt_deactivate) parent->pt_deactivate(parent);