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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Fri, 25 Aug 2017 17:31:52 -0700
Message-ID: <CA+55aFzy981a8Ab+89APi6Qnb9U9xap=0A6XNc+wZsAWngWPzA@mail.gmail.com>
Subject: Re: [PATCH 2/2 v2] sched/wait: Introduce lock breaker in wake_up_page_bit
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To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>, Andi Kleen <ak@linux.intel.com>, Kan Liang <kan.liang@intel.com>, Andrew Morton <akpm@linux-foundation.org>, Johannes Weiner <hannes@cmpxchg.org>, Jan Kara <jack@suse.cz>, Christopher Lameter <cl@linux.com>, "Eric W . Biederman" <ebiederm@xmission.com>, Davidlohr Bueso <dave@stgolabs.net>, linux-mm <linux-mm@kvack.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>

On Fri, Aug 25, 2017 at 4:03 PM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> Let this be a lesson in just *how* little tested, and *how* crap that
> patch probably still is.

I haven't had time to look at it any more (trying to merge the pull
requests that came in today instead), but the more I think about it,
the more I think it was a mistake to do that page_wait_struct
allocation on the stack.

It made it way more fragile and complicated, having to rewrite things
so carefully. A simple slab cache would likely be a lot cleaner and
simpler.

So even if that thing can be made to work, it's probably not worth the pain.

               Linus

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