From: Peter Zijlstra <peterz@infradead.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Byungchul Park <byungchul.park@lge.com>,
Dmitry Vyukov <dvyukov@google.com>,
syzbot
<bot+e7353c7141ff7cbb718e4c888a14fa92de41ebaa@syzkaller.appspotmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Dan Williams <dan.j.williams@intel.com>,
Johannes Weiner <hannes@cmpxchg.org>, Jan Kara <jack@suse.cz>,
jglisse@redhat.com, LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, shli@fb.com, syzkaller-bugs@googlegroups.com,
Thomas Gleixner <tglx@linutronix.de>,
Vlastimil Babka <vbabka@suse.cz>,
ying.huang@intel.com, kernel-team@lge.com
Subject: Re: possible deadlock in lru_add_drain_all
Date: Tue, 31 Oct 2017 14:51:05 +0100 [thread overview]
Message-ID: <20171031135104.rnlytzawi2xzuih3@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20171031131333.pr2ophwd2bsvxc3l@dhcp22.suse.cz>
On Tue, Oct 31, 2017 at 02:13:33PM +0100, Michal Hocko wrote:
> On Mon 30-10-17 16:10:09, Peter Zijlstra wrote:
> > However, that splat translates like:
> >
> > __cpuhp_setup_state()
> > #0 cpus_read_lock()
> > __cpuhp_setup_state_cpuslocked()
> > #1 mutex_lock(&cpuhp_state_mutex)
> >
> >
> >
> > __cpuhp_state_add_instance()
> > #2 mutex_lock(&cpuhp_state_mutex)
>
> this should be #1 right?
Yes
> > cpuhp_issue_call()
> > cpuhp_invoke_ap_callback()
> > #3 wait_for_completion()
> >
> > msr_device_create()
> > ...
> > #4 filename_create()
> > #3 complete()
> >
> >
> >
> > do_splice()
> > #4 file_start_write()
> > do_splice_from()
> > iter_file_splice_write()
> > #5 pipe_lock()
> > vfs_iter_write()
> > ...
> > #6 inode_lock()
> >
> >
> >
> > sys_fcntl()
> > do_fcntl()
> > shmem_fcntl()
> > #5 inode_lock()
And that #6
> > shmem_wait_for_pins()
> > if (!scan)
> > lru_add_drain_all()
> > #0 cpus_read_lock()
> >
> >
> >
> > Which is an actual real deadlock, there is no mixing of up and down.
>
> thanks a lot, this made it more clear to me. It took a while to
> actually see 0 -> 1 -> 3 -> 4 -> 5 -> 0 cycle. I have only focused
> on lru_add_drain_all while it was holding the cpus lock.
Yeah, these things are a pain to read, which is why I always construct
something like the above first.
next prev parent reply other threads:[~2017-10-31 13:51 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <089e0825eec8955c1f055c83d476@google.com>
2017-10-27 9:34 ` possible deadlock in lru_add_drain_all Michal Hocko
2017-10-27 9:44 ` Dmitry Vyukov
2017-10-27 9:47 ` Dmitry Vyukov
2017-10-27 13:42 ` Michal Hocko
2017-10-30 8:22 ` Michal Hocko
2017-10-30 10:09 ` Byungchul Park
2017-10-30 15:10 ` Peter Zijlstra
2017-10-30 15:22 ` Peter Zijlstra
2017-10-31 13:13 ` Michal Hocko
2017-10-31 13:51 ` Peter Zijlstra [this message]
2017-10-31 13:55 ` Dmitry Vyukov
2017-10-31 14:52 ` Peter Zijlstra
2017-10-31 14:58 ` Michal Hocko
2017-10-31 15:10 ` Peter Zijlstra
2017-11-01 8:59 ` Byungchul Park
2017-11-01 12:01 ` Peter Zijlstra
2017-11-01 23:54 ` Byungchul Park
2018-02-14 14:01 ` Dmitry Vyukov
2018-02-14 15:44 ` Michal Hocko
2018-02-14 15:57 ` Dmitry Vyukov
2017-10-31 15:25 ` Peter Zijlstra
2017-10-31 15:45 ` Michal Hocko
2017-10-31 16:30 ` Peter Zijlstra
2017-11-01 8:31 ` Byungchul Park
2017-10-30 10:26 ` Byungchul Park
2017-10-30 11:48 ` Michal Hocko
2017-10-27 11:27 ` Vlastimil Babka
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