From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Nicolai Stange <nicstange@gmail.com>,
gregkh <gregkh@linuxfoundation.org>
Subject: Re: deadlock in synchronize_srcu() in debugfs?
Date: Thu, 23 Mar 2017 08:37:58 -0700 [thread overview]
Message-ID: <20170323153758.GE3637@linux.vnet.ibm.com> (raw)
In-Reply-To: <1490280886.2766.4.camel@sipsolutions.net>
On Thu, Mar 23, 2017 at 03:54:46PM +0100, Johannes Berg wrote:
> Hi,
>
> Before I go hunting - has anyone seen a deadlock in synchronize_srcu()
> in debugfs_remove() before? We're observing that with our (backported,
> but very recent) driver against 4.9 (and 4.10, I think), but there are
> no backports of any debugfs things so the backport itself doesn't seem
> like a likely problem.
>
> sysrq-w shows a lot of tasks blocked on various locks (e.g. RTNL), but
> the ultimate problem is the wireless stack getting blocked on
> debugfs_remove_recursive(), in __synchronize_srcu(), in
> wait_for_completion() (while holding lots of locks, hence the other
> tasks getting stuck).
I have not seen this, but my usual question for __synchronize_srcu()
is if some other task is blocked holding srcu_read_lock() for that
same srcu_struct.
Thanx, Paul
next prev parent reply other threads:[~2017-03-23 15:38 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-23 14:54 deadlock in synchronize_srcu() in debugfs? Johannes Berg
2017-03-23 15:29 ` Johannes Berg
2017-03-24 8:56 ` Johannes Berg
2017-03-24 9:24 ` Johannes Berg
2017-03-24 17:45 ` Paul E. McKenney
2017-03-24 18:51 ` Johannes Berg
2017-03-24 19:33 ` Paul E. McKenney
2017-03-24 20:20 ` Paul E. McKenney
2017-03-27 11:18 ` Johannes Berg
2017-03-23 15:36 ` Nicolai Stange
2017-03-23 15:47 ` Johannes Berg
2017-03-27 11:36 ` Johannes Berg
2017-03-30 7:32 ` Nicolai Stange
2017-03-30 7:55 ` Johannes Berg
2017-03-30 10:27 ` Nicolai Stange
2017-03-30 11:11 ` Johannes Berg
2017-03-31 9:03 ` Nicolai Stange
2017-03-31 9:44 ` Johannes Berg
2017-04-16 9:51 ` [RFC PATCH 0/9] debugfs: per-file removal protection Nicolai Stange
2017-04-16 9:51 ` [RFC PATCH 1/9] debugfs: add support for more elaborate ->d_fsdata Nicolai Stange
2017-04-16 9:51 ` [RFC PATCH 2/9] debugfs: implement per-file removal protection Nicolai Stange
2017-04-18 2:23 ` [lkp-robot] [debugfs] f3e7155d08: BUG:unable_to_handle_kernel kernel test robot
2017-04-23 18:37 ` Nicolai Stange
2017-04-24 6:36 ` Ye Xiaolong
2017-04-16 9:51 ` [RFC PATCH 3/9] debugfs: debugfs_real_fops(): drop __must_hold sparse annotation Nicolai Stange
2017-04-16 9:51 ` [RFC PATCH 4/9] debugfs: convert to debugfs_file_get() and -put() Nicolai Stange
2017-04-16 9:51 ` [RFC PATCH 5/9] IB/hfi1: " Nicolai Stange
2017-04-16 9:51 ` [RFC PATCH 6/9] debugfs: purge obsolete SRCU based removal protection Nicolai Stange
2017-04-16 9:51 ` [RFC PATCH 7/9] debugfs: call debugfs_real_fops() only after debugfs_file_get() Nicolai Stange
2017-04-16 9:51 ` [RFC PATCH 8/9] debugfs: defer debugfs_fsdata allocation to first usage Nicolai Stange
2017-04-18 9:36 ` Johannes Berg
2017-05-02 20:05 ` Nicolai Stange
2017-05-03 5:43 ` Johannes Berg
2017-04-16 9:51 ` [RFC PATCH 9/9] debugfs: free debugfs_fsdata instances Nicolai Stange
2017-04-17 16:01 ` Paul E. McKenney
2017-04-18 9:39 ` Johannes Berg
2017-04-18 13:31 ` Paul E. McKenney
2017-04-18 13:40 ` Johannes Berg
2017-04-18 15:17 ` Paul E. McKenney
2017-04-18 15:20 ` Johannes Berg
2017-04-18 17:19 ` Paul E. McKenney
2017-03-23 15:37 ` Paul E. McKenney [this message]
2017-03-23 15:46 ` deadlock in synchronize_srcu() in debugfs? Johannes Berg
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