Re: [PATCH] mm/page_alloc: Wait for oom_lock before retrying.

From	Petr Mladek <pmladek@suse.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] mm/page_alloc: Wait for oom_lock before retrying.
Date	2017-01-13 13:20 +0100
Message-ID	<sZ8ZR-L2-39@gated-at.bofh.it> (permalink)
References	(5 earlier) <sSBNf-4du-9@gated-at.bofh.it> <sYOop-4Za-19@gated-at.bofh.it> <sYZMR-3st-9@gated-at.bofh.it> <sZ7U6-7f-21@gated-at.bofh.it> <sZ8Gu-ol-13@gated-at.bofh.it>
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On Fri 2017-01-13 20:50:24, Sergey Senozhatsky wrote:
> On (01/13/17 12:03), Petr Mladek wrote:
> [..]
> > > why can't we?
> > 
> > Because it would newer call cond_resched() in non-preemptive kernel
> > with CONFIG_PREEMPT_COUNT disabled. IMHO, we want to call it,
> > for example, when we scroll the entire screen from tty_operations.
> > 
> > Or do I miss anything?
> 
> so... basically. it has never called cond_resched() there. right?
> why is this suddenly a problem now?

But it called cond_resched() when the very same code was called
from tty operations under console_lock() that forced
console_may_schedule = 1;

It will never call cond_resched() from the tty operations
when CONFIG_PREEMPT_COUNT is disabled and we try to detect
the preemption automatically.

Best Regards,
Petr

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Re: [PATCH] mm/page_alloc: Wait for oom_lock before retrying. Petr Mladek <pmladek@suse.com> - 2017-01-12 15:20 +0100
  Re: [PATCH] mm/page_alloc: Wait for oom_lock before retrying. Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-01-13 03:30 +0100
    Re: [PATCH] mm/page_alloc: Wait for oom_lock before retrying. Petr Mladek <pmladek@suse.com> - 2017-01-13 12:10 +0100
      Re: [PATCH] mm/page_alloc: Wait for oom_lock before retrying. Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-01-13 13:00 +0100
        Re: [PATCH] mm/page_alloc: Wait for oom_lock before retrying. Petr Mladek <pmladek@suse.com> - 2017-01-13 13:20 +0100

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