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Groups > linux.kernel > #1714378
| From | Steven Rostedt <rostedt@goodmis.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops |
| Date | 2017-08-17 23:00 +0200 |
| Message-ID | <ufA3w-1Eh-29@gated-at.bofh.it> (permalink) |
| References | <ufdqh-3mR-1@gated-at.bofh.it> <uftbH-5uW-3@gated-at.bofh.it> <ufvQd-7mK-5@gated-at.bofh.it> <ufzKa-1uX-11@gated-at.bofh.it> <ufzTQ-1Ak-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Thu, 17 Aug 2017 20:41:10 +0000
Bart Van Assche <Bart.VanAssche@wdc.com> wrote:
> On Thu, 2017-08-17 at 16:30 -0400, Steven Rostedt wrote:
> > On Thu, 17 Aug 2017 12:24:39 -0400
> > Waiman Long <longman@redhat.com> wrote:
> >
> > > On 08/17/2017 09:34 AM, Steven Rostedt wrote:
> > > > On Wed, 16 Aug 2017 16:40:40 -0400
> > > > Waiman Long <longman@redhat.com> wrote:
> > > >
> > > > > The lockdep code had reported the following unsafe locking scenario:
> > > > >
> > > > > CPU0 CPU1
> > > > > ---- ----
> > > > > lock(s_active#228);
> > > > > lock(&bdev->bd_mutex/1);
> > > > > lock(s_active#228);
> > > > > lock(&bdev->bd_mutex);
> > > >
> > > > Can you show the exact locations of these locks. I have no idea where
> > > > this "s_active" is.
> > >
> > > The s_active isn't an actual lock. It is a reference count (kn->count)
> > > on the sysfs (kernfs) file. Removal of a sysfs file, however, require
> > > a wait until all the references are gone. The reference count is
> > > treated like a rwsem using lockdep instrumentation code.
> >
> > Which kernel is this? I don't see any lockdep annotation around
> > kn->count (doing a git grep, I find it referenced in fs/kernfs/dir.c)
>
> As far as I know the s_active lockdep annotations were introduced in 2007
> through commit 0ab66088c855 ("sysfs: implement sysfs_dirent active reference
> and immediate disconnect"). Today these annotations exist in kernfs:
> $ git grep -nHw dep_map fs/kernfs
> fs/kernfs/dir.c:421: rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_);
> fs/kernfs/dir.c:441: rwsem_release(&kn->dep_map, 1, _RET_IP_);
> fs/kernfs/dir.c:468: rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
> fs/kernfs/dir.c:470: lock_contended(&kn->dep_map, _RET_IP_);
> fs/kernfs/dir.c:478: lock_acquired(&kn->dep_map, _RET_IP_);
> fs/kernfs/dir.c:479: rwsem_release(&kn->dep_map, 1, _RET_IP_);
> fs/kernfs/dir.c:1385: rwsem_acquire(&kn->dep_map, 0, 1, _RET_IP_);
> fs/kernfs/file.c:1000: lockdep_init_map(&kn->dep_map, "s_active", key, 0);
>
Ah thanks. I was searching for the wrong thing. :-/
-- Steve
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[PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Waiman Long <longman@redhat.com> - 2017-08-16 22:50 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Steven Rostedt <rostedt@goodmis.org> - 2017-08-17 15:40 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Waiman Long <longman@redhat.com> - 2017-08-17 18:30 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Steven Rostedt <rostedt@goodmis.org> - 2017-08-17 22:40 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Bart Van Assche <Bart.VanAssche@wdc.com> - 2017-08-17 22:50 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Steven Rostedt <rostedt@goodmis.org> - 2017-08-17 23:00 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Steven Rostedt <rostedt@goodmis.org> - 2017-08-17 23:20 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Waiman Long <longman@redhat.com> - 2017-08-17 23:30 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Steven Rostedt <rostedt@goodmis.org> - 2017-08-18 00:20 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Steven Rostedt <rostedt@goodmis.org> - 2017-08-18 01:30 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Waiman Long <longman@redhat.com> - 2017-08-18 15:50 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Steven Rostedt <rostedt@goodmis.org> - 2017-08-18 00:20 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Steven Rostedt <rostedt@goodmis.org> - 2017-08-17 23:40 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Waiman Long <longman@redhat.com> - 2017-08-18 16:00 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Bart Van Assche <Bart.VanAssche@wdc.com> - 2017-08-18 18:30 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Waiman Long <longman@redhat.com> - 2017-08-18 19:30 +0200
Re: [PATCH v2] blktrace: Fix potentail deadlock between delete & sysfs ops Steven Rostedt <rostedt@goodmis.org> - 2017-08-18 19:30 +0200
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