Date:   Thu, 18 Nov 2021 09:17:04 -0800
From:   Kees Cook <keescook@chromium.org>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Holger =?iso-8859-1?Q?Hoffst=E4tte?= 
        <holger@applied-asynchrony.com>,
        Qi Zheng <zhengqi.arch@bytedance.com>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Justin Forbes <jmforbes@linuxtx.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Shuah Khan <shuah@kernel.org>, patches@kernelci.org,
        lkft-triage@lists.linaro.org, Pavel Machek <pavel@denx.de>,
        Jon Hunter <jonathanh@nvidia.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        stable <stable@vger.kernel.org>,
        Wang Yugui <wangyugui@e16-tech.com>,
        =?iso-8859-1?Q?Fran=E7ois?= Guerraz <kubrick@fgv6.net>,
        Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [PATCH 5.15 000/923] 5.15.3-rc3 review
Message-ID: <202111180912.356B342@keescook>
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On Thu, Nov 18, 2021 at 09:12:59AM +0100, Greg Kroah-Hartman wrote:
> On Wed, Nov 17, 2021 at 04:16:51PM -0800, Kees Cook wrote:
> > On Wed, Nov 17, 2021 at 03:50:17PM -0800, Linus Torvalds wrote:
> > > Sorry for top-posting and quoting this all, but the actual people
> > > involved with the wchan changes don't seem to be on the participant
> > > list.
> > 
> > Adding more folks from a private report and
> > https://bugzilla.kernel.org/show_bug.cgi?id=215031
> > 
> > and for the new people, here's a lore link for this thread:
> > https://lore.kernel.org/stable/YZV02RCRVHIa144u@fedora64.linuxtx.org/
> > 
> > 
> > FWIW, earlier bisection pointed to the stable backport of
> > 5d1ceb3969b6b2e47e2df6d17790a7c5a20fcbb4 being the primary culprit.
> > At first glance it seems to me that the problem with -stable is that an
> > unvetted subset of the wchan refactoring series landed in -stable.
> 
> What would be the vetted subset?  :)

The ones with "Cc: stable" ;)

> Anyway, I have now dropped the following patches that were in the
> 5.15.3-rc tree:
> 	bc9bbb81730e ("x86: Fix get_wchan() to support the ORC unwinder")
> 	42a20f86dc19 ("sched: Add wrapper for get_wchan() to keep task blocked")
> 	5d1ceb3969b6 ("x86: Fix __get_wchan() for !STACKTRACE")
> 
> And will push out another -rc release to let people test.
> 
> If there are any other commits I should have also dropped, please let me
> know.

That looks right to me. These three were part of Peter's much larger
wchan refactoring (of which 42a20f86dc19 was a core part).

Thanks!

-- 
Kees Cook