Re: printk feature for syzbot?

2018-05-15 Thread Steven Rostedt
On Tue, 15 May 2018 14:20:42 +0900 Sergey Senozhatsky wrote: > > And no, NMI handlers do not nest. Yes, we deal with nested NMIs, but in > > those cases, we just set a bit as a latch, and return, and when the > > first NMI is complete, it checks that bit and if

Re: printk feature for syzbot?

2018-05-14 Thread Sergey Senozhatsky
Hello, On (05/11/18 09:37), Steven Rostedt wrote: > > On (05/11/18 11:17), Dmitry Vyukov wrote: > > > > > > From what I see, it seems that interrupts can be nested: > > > > Hm, I thought that in general IRQ handlers run with local IRQs > > disabled on CPU. So, generally, IRQs don't nest. Was

Re: printk feature for syzbot?

2018-05-11 Thread Steven Rostedt
On Fri, 11 May 2018 18:50:04 +0900 Sergey Senozhatsky wrote: > On (05/11/18 11:17), Dmitry Vyukov wrote: > > > > From what I see, it seems that interrupts can be nested: > > Hm, I thought that in general IRQ handlers run with local IRQs > disabled on CPU.

Re: printk feature for syzbot?

2018-05-11 Thread Sergey Senozhatsky
On (05/11/18 11:17), Dmitry Vyukov wrote: > > From what I see, it seems that interrupts can be nested: Hm, I thought that in general IRQ handlers run with local IRQs disabled on CPU. So, generally, IRQs don't nest. Was I wrong? NMIs can nest, that's true; but I thought that at least IRQs don't.

Re: printk feature for syzbot?

2018-05-11 Thread Dmitry Vyukov
On Fri, May 11, 2018 at 8:21 AM, Sergey Senozhatsky wrote: > On (05/11/18 11:38), Tetsuo Handa wrote: >> > >> > So you basically want to have one more con_msg_format_flags? Do >> > you want to track a context which prints out a messages or the >> > context which

Re: printk feature for syzbot?

2018-05-11 Thread Sergey Senozhatsky
On (05/11/18 11:38), Tetsuo Handa wrote: > > > > So you basically want to have one more con_msg_format_flags? Do > > you want to track a context which prints out a messages or the > > context which "generated" the message? A CPU/task that stores > > a logbuf entry - vprintk_emit() - is not always

Re: printk feature for syzbot?

2018-05-10 Thread Sergey Senozhatsky
On (05/10/18 23:50), Tetsuo Handa wrote: > What I meant is nothing but something like below (i.e. inject context ID > before > string to print) > > -sprintf(printk_buf + offset, "[ %s] %s", stamp, string_to_print); > +cpu = smp_processor_id() > +if (in_nmi()) > + sprintf(printk_buf +

Re: printk feature for syzbot?

2018-05-10 Thread Tetsuo Handa
Sergey Senozhatsky wrote: > On (04/26/18 12:06), Petr Mladek wrote: > > > > > Petr, Steven, Fengguang, what do you think? Do you have any objections? > > > Ideas? > > > > I wonder if we could create some mechanism that would help to extend > > struct printk_log easier in the future. > > Hm,

Re: printk feature for syzbot?

2018-05-10 Thread Steven Rostedt
On Thu, 10 May 2018 21:11:22 +0900 Sergey Senozhatsky wrote: > > The patchset was rejected by Linus because it would broke some > > userspace tool, e.g. systemd, that depend on the format and semantic > > provided by /dev/kmsg[2]. > > Right, but I think I

Re: printk feature for syzbot?

2018-05-10 Thread Sergey Senozhatsky
On (05/10/18 13:30), Petr Mladek wrote: [..] > I guess that you are talking about the patchset adding possibility > to use different time-stamps[1]. It changed the semantic of the > timestamp. All the tools needed an update to show the timestamp > correctly. > > The patchset was rejected by Linus

Re: printk feature for syzbot?

2018-05-10 Thread Petr Mladek
On Thu 2018-05-10 13:22:06, Sergey Senozhatsky wrote: > On (04/26/18 12:06), Petr Mladek wrote: > > > > > Petr, Steven, Fengguang, what do you think? Do you have any objections? > > > Ideas? > > > > I wonder if we could create some mechanism that would help to extend > > struct printk_log easier

Re: printk feature for syzbot?

2018-05-09 Thread Sergey Senozhatsky
On (04/26/18 12:06), Petr Mladek wrote: > > > Petr, Steven, Fengguang, what do you think? Do you have any objections? > > Ideas? > > I wonder if we could create some mechanism that would help to extend > struct printk_log easier in the future. Hm, interesting idea. > I know only about crash

Re: printk feature for syzbot?

2018-04-26 Thread Petr Mladek
On Tue 2018-04-24 10:33:36, Sergey Senozhatsky wrote: > Yes, Tetsuo, we use a bunch of "printk prefix" extensions at Samsung. > For instance, we prefix printk messages with the CPU number: messages > sometimes mix up, we also see partial pr_cont flushes, and so on. > Grep-ping serial logs by CPU

Re: printk feature for syzbot?

2018-04-24 Thread Steven Rostedt
On Tue, 24 Apr 2018 10:33:36 +0900 Sergey Senozhatsky wrote: > Petr, Steven, Fengguang, what do you think? Do you have any objections? > Ideas? If it can be turned off by a config option, I'm fine with it. -- Steve

Re: printk feature for syzbot?

2018-04-23 Thread Sergey Senozhatsky
Let me Cc Petr, Steven and Fengguang on this On (04/23/18 15:40), Dmitry Vyukov wrote: > On Mon, Apr 23, 2018 at 3:33 PM, Tetsuo Handa > wrote: > > Hello, Sergey. > > > > Recently I'm fixing bugs reported by syzbot ( > > https://syzkaller.appspot.com/ ). > >