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Groups > linux.kernel > #1620011
| From | Sergey Senozhatsky <sergey.senozhatsky@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage |
| Date | 2017-04-10 17:10 +0200 |
| Message-ID | <tuJ74-2kr-35@gated-at.bofh.it> (permalink) |
| References | (5 earlier) <ttBuW-78a-13@gated-at.bofh.it> <ttDQ6-rS-29@gated-at.bofh.it> <tui6T-1tb-21@gated-at.bofh.it> <tuzAJ-4sI-3@gated-at.bofh.it> <tuG9b-av-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On (04/10/17 13:54), Petr Mladek wrote: [..] > > > that works with my proposal, but not with yours. Seen it happen many > > > times before. > > > > I see your point, sure. > > I can't completely agree on "that works with my proposal, but not with yours." > > > > on SMP system this would be true only if no other CPU holds the console_sem > > at the time we call printk(). (skipping irrelevant cases when we have suspended > > console or !online CPU and !CON_ANYTIME console). and there is nothing that > > makes "no other CPU holds the console_sem" always true on SMP system at any > > given point in time. so no, "A always works, B never works" is not accurate. > > > > but, once again, I see your point. > > A compromise might be to move the offloading from vprintk_emit() to > console_unlock(). By other words, the printk could always try to > flush some messages to the console. The console might trigger > the offload (wakeup kthread) after few lines yep, that's the proposal. hm, this also should align with one more thing. we briefly discussed it before, and it was on my list, that wake_up(printk_kthread) _eventually_ better be moved to console_unlock() [1] (I also had it in the slides at KS, but I believe we didn't have much time back then). vprintk_emit() is not the only console_lock() caller. user space does console_lock() and console_unlock() calls, and in some cases a user space process can stuck in system call printing kernel messages to a potentially slow console [2]. it can be unpleasant, but far less dramatic than doing console_unlock() from IRQ, or under spin_lock. so it was moved down the list. seems we have one more reason to reshuffle the list and do offloading from console_unlock() from the beginning. will take a look. /* in our "in-house" kernels we do 'async' console_unlock(). not exactly the way it's shown in [1], but quite similar. */ [1] https://marc.info/?l=linux-kernel&m=145750373530161 [2] https://marc.info/?l=linux-kernel&m=145762735308470 -ss
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[RFC][PATCHv2 0/8] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:30 +0200
[RFC][PATCHv2 2/8] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:30 +0200
Re: [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Petr Mladek <pmladek@suse.com> - 2017-04-04 11:10 +0200
Re: [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-04 11:40 +0200
Re: [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Pavel Machek <pavel@ucw.cz> - 2017-04-06 19:20 +0200
Re: [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-07 07:20 +0200
Re: [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Pavel Machek <pavel@ucw.cz> - 2017-04-07 09:30 +0200
Re: [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-07 10:20 +0200
Re: [RFC][PATCHv2 2/8] printk: introduce printing kernel thread Pavel Machek <pavel@ucw.cz> - 2017-04-07 14:10 +0200
[RFC][PATCHv2 5/8] sysrq: switch to printk.emergency mode in unsafe places Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:30 +0200
Re: [RFC][PATCHv2 5/8] sysrq: switch to printk.emergency mode in unsafe places Petr Mladek <pmladek@suse.com> - 2017-03-31 17:40 +0200
Re: [RFC][PATCHv2 5/8] sysrq: switch to printk.emergency mode in unsafe places Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-04-01 02:10 +0200
[RFC][PATCHv2 1/8] printk: move printk_pending out of per-cpu Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:40 +0200
Re: [RFC][PATCHv2 1/8] printk: move printk_pending out of per-cpu Petr Mladek <pmladek@suse.com> - 2017-03-31 15:20 +0200
Re: [RFC][PATCHv2 1/8] printk: move printk_pending out of per-cpu Peter Zijlstra <peterz@infradead.org> - 2017-03-31 15:40 +0200
Re: [RFC][PATCHv2 1/8] printk: move printk_pending out of per-cpu Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-03 13:30 +0200
Re: [RFC][PATCHv2 1/8] printk: move printk_pending out of per-cpu Petr Mladek <pmladek@suse.com> - 2017-04-03 14:50 +0200
[RFC][PATCHv2 6/8] kexec: switch to printk.emergency mode in unsafe places Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:40 +0200
Re: [RFC][PATCHv2 6/8] kexec: switch to printk.emergency mode in unsafe places Petr Mladek <pmladek@suse.com> - 2017-03-31 17:40 +0200
[RFC][PATCHv2 8/8] printk: enable printk offloading Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:40 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-03-31 04:40 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-03-31 06:10 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Ye Xiaolong <xiaolong.ye@intel.com> - 2017-03-31 08:50 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-31 16:50 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage ebiederm@xmission.com (Eric W. Biederman) - 2017-03-31 17:40 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Jan Kara <jack@suse.cz> - 2017-04-03 11:40 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Petr Mladek <pmladek@suse.com> - 2017-04-03 12:10 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Pavel Machek <pavel@ucw.cz> - 2017-04-06 19:40 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-07 06:50 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Pavel Machek <pavel@ucw.cz> - 2017-04-07 09:20 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-07 09:50 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Pavel Machek <pavel@ucw.cz> - 2017-04-07 10:20 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-07 14:20 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Pavel Machek <pavel@ucw.cz> - 2017-04-07 14:50 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Steven Rostedt <rostedt@goodmis.org> - 2017-04-07 16:50 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-04-07 17:20 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Peter Zijlstra <peterz@infradead.org> - 2017-04-07 17:30 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-04-07 17:50 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage ebiederm@xmission.com (Eric W. Biederman) - 2017-04-09 20:30 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-10 06:50 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Pavel Machek <pavel@ucw.cz> - 2017-04-09 12:20 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-10 07:00 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Petr Mladek <pmladek@suse.com> - 2017-04-10 14:00 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-04-10 17:10 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Pavel Machek <pavel@ucw.cz> - 2017-04-10 20:50 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-11 03:50 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-04-11 18:30 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Pavel Machek <pavel@ucw.cz> - 2017-04-12 20:50 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-13 06:40 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-13 08:00 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-13 10:30 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Petr Mladek <pmladek@suse.com> - 2017-04-13 16:10 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-14 06:50 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Steven Rostedt <rostedt@goodmis.org> - 2017-04-07 16:40 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Pavel Machek <pavel@ucw.cz> - 2017-04-09 12:00 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-03 13:00 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Ye Xiaolong <xiaolong.ye@intel.com> - 2017-04-05 09:40 +0200
Re: [printk] fbc14616f4: BUG:kernel_reboot-without-warning_in_test_stage Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-05 10:50 +0200
Re: [RFC][PATCHv2 8/8] printk: enable printk offloading Petr Mladek <pmladek@suse.com> - 2017-04-03 17:50 +0200
Re: [RFC][PATCHv2 8/8] printk: enable printk offloading Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-04-04 14:30 +0200
[RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe places Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:40 +0200
Re: [RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe places Petr Mladek <pmladek@suse.com> - 2017-03-31 17:10 +0200
Re: [RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe places Pavel Machek <pavel@ucw.cz> - 2017-04-06 19:30 +0200
Re: [RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe places Andreas Mohr <andi@lisas.de> - 2017-04-09 13:00 +0200
Re: [RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe places Petr Mladek <pmladek@suse.com> - 2017-04-10 14:30 +0200
Re: [RFC][PATCHv2 4/8] pm: switch to printk.emergency mode in unsafe places Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-04-10 16:40 +0200
[RFC][PATCHv2 7/8] printk: add printk emergency_mode parameter Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-03-29 11:40 +0200
Re: [RFC][PATCHv2 7/8] printk: add printk emergency_mode parameter Petr Mladek <pmladek@suse.com> - 2017-04-03 17:30 +0200
Re: [RFC][PATCHv2 7/8] printk: add printk emergency_mode parameter Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-04-04 10:30 +0200
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