Re: [PATCH] mm: don't warn about allocations which stall for too long

From: Steven Rostedt <rostedt@goodmis.org>
To: Petr Mladek <pmladek@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	akpm@linux-foundation.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Mel Gorman <mgorman@suse.de>, Michal Hocko <mhocko@kernel.org>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	"yuwang.yuwang" <yuwang.yuwang@alibaba-inc.com>
Subject: Re: [PATCH] mm: don't warn about allocations which stall for too long
Date: Wed, 1 Nov 2017 11:36:47 -0400	[thread overview]
Message-ID: <20171101113647.243eecf8@gandalf.local.home> (raw)
In-Reply-To: <20171101133845.GF20040@pathway.suse.cz>

On Wed, 1 Nov 2017 14:38:45 +0100
Petr Mladek <pmladek@suse.com> wrote:

> This was my fear as well. Steven argued that this was theoretical.
> And I do not have a real-life bullets against this argument at
> the moment.

And my argument is still if such a situation happens, the system is so
fscked up that it should just crash.

> 
> My current main worry with Steven's approach is a risk of deadlocks
> that Jan Kara saw when he played with similar solution.

And if there exists such a deadlock, then the deadlock exists today.

> 
> Also I am afraid that it would add yet another twist to the console
> locking operations. It is already quite hard to follow the logic,
> see the games with:
> 
> 	+ console_locked
> 	+ console_suspended
> 	+ can_use_console()
> 	+ exclusive_console
> 
> And Steven is going to add:
> 
> 	+ console_owner
> 	+ waiter

Agreed. Console_lock is just ugly. And this may just make it uglier :-/

> 
> But let's wait for the patch. It might look and work nicely
> in the end.

Oh, I need to write a patch? Bah, I guess I should. Where's all those
developers dying to do kernel programing where I can pass this off to?

-- Steve