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Groups > linux.kernel > #1695487
| From | Michael Wang <yun.wang@profitbricks.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [ Linux 4.4 stable ] missing 'printk: set may_schedule for some of console_trylock() callers' |
| Date | 2017-07-25 10:30 +0200 |
| Message-ID | <u73o6-oR-19@gated-at.bofh.it> (permalink) |
| Organization | linux.* mail to news gateway |
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
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[ Linux 4.4 stable ] missing 'printk: set may_schedule for some of console_trylock() callers' Michael Wang <yun.wang@profitbricks.com> - 2017-07-25 10:30 +0200
Re: [ Linux 4.4 stable ] missing 'printk: set may_schedule for some of console_trylock() callers' Greg KH <gregkh@linuxfoundation.org> - 2017-07-25 16:00 +0200
Re: [ Linux 4.4 stable ] missing 'printk: set may_schedule for some of console_trylock() callers' Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-07-25 18:40 +0200
Re: [ Linux 4.4 stable ] missing 'printk: set may_schedule for some of console_trylock() callers' Petr Mladek <pmladek@suse.com> - 2017-07-26 10:50 +0200
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