From: Boqun Feng <boqun.feng@gmail.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Zhouyi Zhou <zhouzhouyi@gmail.com>,
paulmck@kernel.org,
Oleksandr Natalenko <oleksandr@natalenko.name>,
linux-kernel <linux-kernel@vger.kernel.org>,
stable@vger.kernel.org, Chris Clayton <chris2553@googlemail.com>,
Chris Rankin <rankincj@gmail.com>,
Josh Triplett <josh@joshtriplett.org>,
Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Joel Fernandes <joel@joelfernandes.org>,
rcu <rcu@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>, Miaohe Lin <linmiaohe@huawei.com>,
"Huang, Ying" <ying.huang@intel.com>
Subject: Re: linux-5.13.2: warning from kernel/rcu/tree_plugin.h:359
Date: Mon, 19 Jul 2021 18:14:21 +0800 [thread overview]
Message-ID: <YPVQfaamqwu1PRrK@boqun-archlinux> (raw)
In-Reply-To: <YPTmtNMJpykEpzx6@casper.infradead.org>
On Mon, Jul 19, 2021 at 03:43:00AM +0100, Matthew Wilcox wrote:
> On Mon, Jul 19, 2021 at 10:24:18AM +0800, Zhouyi Zhou wrote:
> > Meanwhile, I examined the 5.12.17 by naked eye, and found a suspicious place
> > that could possibly trigger that problem:
> >
> > struct swap_info_struct *get_swap_device(swp_entry_t entry)
> > {
> > struct swap_info_struct *si;
> > unsigned long offset;
> >
> > if (!entry.val)
> > goto out;
> > si = swp_swap_info(entry);
> > if (!si)
> > goto bad_nofile;
> >
> > rcu_read_lock();
> > if (data_race(!(si->flags & SWP_VALID)))
> > goto unlock_out;
> > offset = swp_offset(entry);
> > if (offset >= si->max)
> > goto unlock_out;
> >
> > return si;
> > bad_nofile:
> > pr_err("%s: %s%08lx\n", __func__, Bad_file, entry.val);
> > out:
> > return NULL;
> > unlock_out:
> > rcu_read_unlock();
> > return NULL;
> > }
> > I guess the function "return si" without a rcu_read_unlock.
>
> Yes, but the caller is supposed to call put_swap_device() which
> calls rcu_read_unlock(). See commit eb085574a752.
Right, but we need to make sure there is no sleepable function called
before put_swap_device() called, and the call trace showed the following
happened:
do_swap_page():
si = get_swap_device():
rcu_read_lock();
lock_page_or_retry():
might_sleep(); // call a sleepable function inside RCU read-side c.s.
__lock_page_or_retry():
wait_on_page_bit_common():
schedule():
rcu_note_context_switch();
// Warn here
put_swap_device();
rcu_read_unlock();
, which introduced by commit 2799e77529c2a
[Copy the author]
Regards,
Boqun
next prev parent reply other threads:[~2021-07-19 10:16 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <c9fd1311-662c-f993-c8ef-54af036f2f78@googlemail.com>
2021-07-18 21:01 ` linux-5.13.2: warning from kernel/rcu/tree_plugin.h:359 Oleksandr Natalenko
2021-07-18 21:03 ` Oleksandr Natalenko
2021-07-18 21:22 ` Matthew Wilcox
2021-07-18 21:36 ` Chris Clayton
2021-07-18 21:59 ` Paul E. McKenney
2021-07-18 22:51 ` Matthew Wilcox
2021-07-19 1:53 ` Paul E. McKenney
2021-07-19 2:24 ` Zhouyi Zhou
2021-07-19 2:27 ` Zhouyi Zhou
2021-07-19 2:43 ` Matthew Wilcox
2021-07-19 2:59 ` Zhouyi Zhou
2021-07-19 10:14 ` Boqun Feng [this message]
2021-07-19 11:12 ` Miaohe Lin
2021-07-19 11:17 ` Oleksandr Natalenko
2021-07-19 11:22 ` Matthew Wilcox
2021-07-19 11:50 ` Miaohe Lin
2021-07-19 11:59 ` Oleksandr Natalenko
2021-07-19 12:08 ` Miaohe Lin
2021-07-19 12:12 ` Oleksandr Natalenko
2021-07-19 12:16 ` Matthew Wilcox
2021-07-19 12:23 ` Oleksandr Natalenko
2021-07-19 16:47 ` Zhouyi Zhou
2021-07-19 16:56 ` Zhouyi Zhou
2021-07-22 7:30 ` Chris Clayton
2021-07-22 8:57 ` Zhouyi Zhou
2021-07-22 12:36 ` Matthew Wilcox
2021-07-22 13:26 ` Greg KH
2021-07-22 14:00 ` Greg KH
2021-07-23 1:51 ` Miaohe Lin
2021-07-23 7:02 ` Greg KH
2021-07-23 7:13 ` Miaohe Lin
2021-07-22 17:44 ` Zhouyi Zhou
2021-07-22 14:05 ` Paul E. McKenney
2021-07-19 12:17 ` Miaohe Lin
2021-07-19 7:32 ` Chris Clayton
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