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

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Message-ID: <20171101113647.243eecf8@gandalf.local.home>
Date:   Wed, 1 Nov 2017 11:36:47 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Vlastimil Babka <vbabka@...e.cz>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Cong Wang <xiyou.wangcong@...il.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Mel Gorman <mgorman@...e.de>, Michal Hocko <mhocko@...nel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        "yuwang.yuwang" <yuwang.yuwang@...baba-inc.com>
Subject: Re: [PATCH] mm: don't warn about allocations which stall for too
 long

On Wed, 1 Nov 2017 14:38:45 +0100
Petr Mladek <pmladek@...e.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