linux-kernel - Re: [PATCH] kthread: finer-grained lockdep/cross-release completion

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Message-ID: <20171218071159.GW26573@phenom.ffwll.local>
Date:   Mon, 18 Dec 2017 08:11:59 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Daniel Vetter <daniel.vetter@...ll.ch>,
        LKML <linux-kernel@...r.kernel.org>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Intel Graphics Development <intel-gfx@...ts.freedesktop.org>,
        Tvrtko Ursulin <tvrtko.ursulin@...el.com>,
        Marta Lofstedt <marta.lofstedt@...el.com>,
        Byungchul Park <byungchul.park@....com>,
        Ingo Molnar <mingo@...nel.org>, Tejun Heo <tj@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Thomas Gleixner <tglx@...utronix.de>, Shaohua Li <shli@...com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jens Axboe <axboe@...nel.dk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jonathan Corbet <corbet@....net>,
        Oleg Nesterov <oleg@...hat.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] kthread: finer-grained lockdep/cross-release completion

On Mon, Dec 11, 2017 at 10:19:28AM +0100, Daniel Vetter wrote:
> On Fri, Dec 08, 2017 at 11:54:19AM +0100, Peter Zijlstra wrote:
> > On Thu, Dec 07, 2017 at 11:08:49AM +0100, Daniel Vetter wrote:
> > > Since -rc1 we're hitting a bunch of lockdep splats using the new
> > > cross-release stuff around the 2 kthread completions. In all cases
> > > they are because totally independent uses of kthread are mixed up by
> > > lockdep into the same locking class, creating artificial deadlocks.
> > > 
> > > Fix this by converting kthread code in the same way as e.g.
> > > alloc_workqueue already works: Use macros for the public api so we can
> > > have a callsite specific lockdep key, then pass that through the
> > > entire callchain. Due to the many entry points this is slightly
> > > tedious.
> > > 
> > > Cc: Tvrtko Ursulin <tvrtko.ursulin@...el.com>
> > > Cc: Marta Lofstedt <marta.lofstedt@...el.com>
> > > Cc: Byungchul Park <byungchul.park@....com>
> > > Cc: Ingo Molnar <mingo@...nel.org>
> > > Cc: Peter Zijlstra <peterz@...radead.org>
> > > Cc: Tejun Heo <tj@...nel.org>
> > > Cc: Kees Cook <keescook@...omium.org>
> > > Cc: Thomas Gleixner <tglx@...utronix.de>
> > > Cc: Shaohua Li <shli@...com>
> > > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > > Cc: Jens Axboe <axboe@...nel.dk>
> > > Cc: Daniel Vetter <daniel.vetter@...ll.ch>
> > > Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> > > Cc: Jonathan Corbet <corbet@....net>
> > > Cc: Oleg Nesterov <oleg@...hat.com>
> > > References: https://bugs.freedesktop.org/show_bug.cgi?id=103950
> > > Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
> > 
> > Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> 
> Who's going to pick this up? Ingo, Andrew?

This didn't seem to have made it into -rc4. Anything needed to get it
going?

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch