Re: [RFC][PATCH] printk: do not flush printk_safe from irq_work

2018-02-02 Thread Petr Mladek
On Fri 2018-02-02 13:17:08, Petr Mladek wrote: > On Thu 2018-02-01 11:46:47, Sergey Senozhatsky wrote: > > On (01/30/18 13:23), Petr Mladek wrote: > > [..] > > > > If the system is in "big troubles" then what makes irq_work more > > > > possible? Local IRQs can stay disabled, just like preemption.

Re: [RFC][PATCH] printk: do not flush printk_safe from irq_work

2018-02-02 Thread Petr Mladek
On Thu 2018-02-01 11:46:47, Sergey Senozhatsky wrote: > On (01/30/18 13:23), Petr Mladek wrote: > [..] > > > If the system is in "big troubles" then what makes irq_work more > > > possible? Local IRQs can stay disabled, just like preemption. I > > > guess when the troubles are really big our strate

Re: [RFC][PATCH] printk: do not flush printk_safe from irq_work

2018-02-02 Thread Petr Mladek
On Fri 2018-02-02 10:07:20, Sergey Senozhatsky wrote: > On (02/01/18 13:00), Steven Rostedt wrote: > > On Mon, 29 Jan 2018 11:29:18 +0900 > > Sergey Senozhatsky wrote: > [..] > > > If the system is in "big troubles" then what makes irq_work more > > > possible? Local IRQs can stay disabled, just l

Re: [RFC][PATCH] printk: do not flush printk_safe from irq_work

2018-02-01 Thread Sergey Senozhatsky
On (02/01/18 13:00), Steven Rostedt wrote: > On Mon, 29 Jan 2018 11:29:18 +0900 > Sergey Senozhatsky wrote: [..] > > If the system is in "big troubles" then what makes irq_work more > > possible? Local IRQs can stay disabled, just like preemption. I > > guess when the troubles are really big our s

Re: [RFC][PATCH] printk: do not flush printk_safe from irq_work

2018-02-01 Thread Steven Rostedt
On Mon, 29 Jan 2018 11:29:18 +0900 Sergey Senozhatsky wrote: > On (01/26/18 16:26), Petr Mladek wrote: > [..] > > First, this delays showing eventually valuable information until > > the preemption is enabled. It might never happen if the system > > is in big troubles. In each case, it might be m

Re: [RFC][PATCH] printk: do not flush printk_safe from irq_work

2018-01-31 Thread Sergey Senozhatsky
On (01/30/18 13:23), Petr Mladek wrote: [..] > > If the system is in "big troubles" then what makes irq_work more > > possible? Local IRQs can stay disabled, just like preemption. I > > guess when the troubles are really big our strategy is the same > > for both wq and irq_work solutions - we keep

Re: [RFC][PATCH] printk: do not flush printk_safe from irq_work

2018-01-30 Thread Petr Mladek
On Mon 2018-01-29 11:29:18, Sergey Senozhatsky wrote: > On (01/26/18 16:26), Petr Mladek wrote: > [..] > > First, this delays showing eventually valuable information until > > the preemption is enabled. It might never happen if the system > > is in big troubles. In each case, it might be much longe

Re: [RFC][PATCH] printk: do not flush printk_safe from irq_work

2018-01-28 Thread Sergey Senozhatsky
On (01/26/18 16:26), Petr Mladek wrote: [..] > First, this delays showing eventually valuable information until > the preemption is enabled. It might never happen if the system > is in big troubles. In each case, it might be much longer delay > than it was before. If the system is in "big troubles

Re: [RFC][PATCH] printk: do not flush printk_safe from irq_work

2018-01-27 Thread Petr Mladek
On Wed 2018-01-24 18:37:23, Sergey Senozhatsky wrote: > Tejun Heo reported that net_console can cause recursive printk()-s > from call_console_drivers() (under OOM/etc.) and this can lockup that > CPU, because CPU calls call_console_drivers() to print pending logbufs, > but recursive printk() issue

[RFC][PATCH] printk: do not flush printk_safe from irq_work

2018-01-24 Thread Sergey Senozhatsky
Tejun Heo reported that net_console can cause recursive printk()-s from call_console_drivers() (under OOM/etc.) and this can lockup that CPU, because CPU calls call_console_drivers() to print pending logbufs, but recursive printk() issued by one of console drivers adds several new messages to the l