Bug 1429977

Summary: workqueue: use rcu_readlock() in put_pwq_unlocked()
Product: Red Hat Enterprise Linux 7 Reporter: John Kacur <jkacur>
Component: kernel-rtAssignee: John Kacur <jkacur>
kernel-rt sub component: Other QA Contact: Jiri Kastner <jkastner>
Status: CLOSED ERRATA Docs Contact:
Severity: medium    
Priority: medium CC: bhu, jkacur, jshortt, lgoncalv, williams
Version: 7.4   
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Unspecified   
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Clone Of: Environment:
Last Closed: 2017-08-01 19:02:59 UTC Type: Bug
Regression: --- Mount Type: ---
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Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1353018, 1410158    
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Description Flags
workqueue-use-rcu_readlock-in-put_pwq_unlocked none

Description John Kacur 2017-03-07 15:33:12 UTC 
The RCU sched protection was changed to RCU only and so all IRQ-off and
preempt-off disabled region were changed to the relevant rcu-read-lock
primitives. One was missed and triggered:
|[ BUG: bad unlock balance detected! ]
|4.4.30-rt41 #51 Tainted: G        W
|btattach/345 is trying to release lock (
|Unable to handle kernel paging request at virtual address 6b6b6bbb
|Backtrace:
|[<c016b5a0>] (lock_release) from [<c0804844>] (rt_spin_unlock+0x20/0x30)
|[<c0804824>] (rt_spin_unlock) from [<c0138954>] (put_pwq_unlocked+0xa4/0x118)
|[<c01388b0>] (put_pwq_unlocked) from [<c0138b2c>] (destroy_workqueue+0x164/0x1b0)
|[<c01389c8>] (destroy_workqueue) from [<c078e1ac>] (hci_unregister_dev+0x120/0x21c)
|[<c078e08c>] (hci_unregister_dev) from [<c054f658>] (hci_uart_tty_close+0x90/0xbc)
|[<c054f5c8>] (hci_uart_tty_close) from [<c03a2be8>] (tty_ldisc_close+0x50/0x58)
|[<c03a2b98>] (tty_ldisc_close) from [<c03a2cb4>] (tty_ldisc_kill+0x18/0x78)
|[<c03a2c9c>] (tty_ldisc_kill) from [<c03a3528>] (tty_ldisc_release+0x100/0x134)
|[<c03a3428>] (tty_ldisc_release) from [<c039cd68>] (tty_release+0x3bc/0x460)
|[<c039c9ac>] (tty_release) from [<c020cc08>] (__fput+0xe0/0x1b4)
|[<c020cb28>] (__fput) from [<c020cd3c>] (____fput+0x10/0x14)
|[<c020cd2c>] (____fput) from [<c013e0d4>] (task_work_run+0xa4/0xb8)
|[<c013e030>] (task_work_run) from [<c0121754>] (do_exit+0x40c/0x8b0)
|[<c0121348>] (do_exit) from [<c0122ff8>] (do_group_exit+0x54/0xc4)
Comment 2 John Kacur 2017-03-07 15:39:34 UTC 
Created attachment 1260854 [details]
workqueue-use-rcu_readlock-in-put_pwq_unlocked
Comment 7 Jiri Kastner 2017-05-16 09:48:14 UTC 
no reproducer available setting sanityonly
Comment 9 errata-xmlrpc 2017-08-01 19:02:59 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2017:2077
Comment 10 errata-xmlrpc 2017-08-02 00:25:36 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2017:2077