From: Michael Wang <yun.wang@profitbricks.com>
To: gregkh@linuxfoundation.org
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: [ Linux 4.4 stable ] missing 'printk: set may_schedule for some of console_trylock() callers'
Date: Tue, 25 Jul 2017 10:28:16 +0200 [thread overview]
Message-ID: <8cfee169-00eb-4b08-3440-ccf654a056aa@profitbricks.com> (raw)
Hi, greg k-h
During our testing with 4.4.73 we got soft lockup like:
NMI watchdog: BUG: soft lockup - CPU#2 stuck for 23s! [systemd-udevd:856]
...
Call Trace:
[<ffffffff8109d139>] vprintk_emit+0x319/0x4a0
[<ffffffff8112182d>] printk_emit+0x33/0x3b
[<ffffffff812f9e9c>] ? simple_strtoull+0x2c/0x50
[<ffffffff8109d39a>] devkmsg_write+0xaa/0x100
[<ffffffff8109d2f0>] ? vprintk+0x30/0x30
[<ffffffff811915f2>] do_readv_writev+0x1c2/0x270
[<ffffffff8117899d>] ? kmem_cache_free+0x7d/0x1a0
[<ffffffff81191729>] vfs_writev+0x39/0x50
[<ffffffff8119240a>] SyS_writev+0x4a/0xd0
[<ffffffff8158bc97>] entry_SYSCALL_64_fastpath+0x12/0x6a
Currently in 4.4 the console_unlock() called by vprintk_emit() is with
preemption disabled, so the cond_resched is not working, and soft lockup
appear if it take too much time on writing data into every console.
We found the upstream patch:
commit 6b97a20d3a79 printk: set may_schedule for some of console_trylock() callers
which should have addressed this issue, but not included in the latest 4.4.78 stable
yet, is there any plan on backport it in future?
Regards,
Michael Wang
next reply other threads:[~2017-07-25 8:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-25 8:28 Michael Wang [this message]
2017-07-25 13:57 ` Greg KH
2017-07-25 16:33 ` Sergey Senozhatsky
2017-07-26 8:44 ` Petr Mladek
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