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From: Johannes Berg <johannes@sipsolutions.net>
To: paulmck@linux.vnet.ibm.com, Nicolai Stange <nicstange@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 9/9] debugfs: free debugfs_fsdata instances
Date: Tue, 18 Apr 2017 11:39:27 +0200	[thread overview]
Message-ID: <1492508367.2472.9.camel@sipsolutions.net> (raw)
In-Reply-To: <20170417160121.GP3956@linux.vnet.ibm.com>

On Mon, 2017-04-17 at 09:01 -0700, Paul E. McKenney wrote:

> If you have not already done so, please run this with debug enabled,
> especially CONFIG_PROVE_LOCKING=y (which implies CONFIG_PROVE_RCU=y).
> This is important because there are configurations for which the
> deadlocks you saw with SRCU turn into silent failure, including
> memory corruption.
> CONFIG_PROVE_RCU=y will catch many of those situations.

Can you elaborate on that? I think we may have had CONFIG_PROVE_RCU
enabled in the builds where we saw the problem, but I'm not sure.

Can you say which configurations you're thinking of? And perhaps what
kind of corruption you're thinking of also? I'm having a hard time
imagining any corruption that should happen?

Nicolai probably never even ran into this problem, though it should be
easy to reproduce.

johannes

  reply	other threads:[~2017-04-18  9:39 UTC|newest]

Thread overview: 46+ 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
2017-04-18  2:23                     ` kernel test robot
2017-04-23 18:37                     ` Nicolai Stange
2017-04-23 18:37                       ` Nicolai Stange
2017-04-24  6:36                       ` Ye Xiaolong
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 [this message]
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 ` deadlock in synchronize_srcu() in debugfs? Paul E. McKenney
2017-03-23 15:46   ` Johannes Berg

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