linux-kernel - Re: [PATCH] mm/page_alloc: Wait for oom

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Date:   Fri, 13 Jan 2017 12:15:29 +0100
From:   Petr Mladek <pmladek@...e.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        mhocko@...e.com, linux-mm@...ck.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.cz>, linux-fbdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/page_alloc: Wait for oom_lock before retrying.

On Fri 2017-01-13 12:53:07, Sergey Senozhatsky wrote:
> On (01/13/17 11:52), Sergey Senozhatsky wrote:
> [..]
> > and we really don't want to cond_resched() when we are in panic.
> > that's why console_flush_on_panic() sets it to zero explicitly.
> > 
> > console_trylock() checks oops_in_progress, so re-taking the semaphore
> > when we are in
> > 
> > 	panic()
> > 	 console_flush_on_panic()
> >           console_unlock()
> >            console_trylock()
> > 
> > should be OK. as well as doing get_console_conditional_schedule() somewhere
> > in console driver code.
> 
> d'oh... no, this is false. console_flush_on_panic() is called after we
> bust_spinlocks(0), BUT with local IRQs disabled. so console_trylock()
> would still set console_may_schedule to 0.

Ah, you found it yourself.

Best Regards,
Petr