All of lore.kernel.org
 help / color / mirror / Atom feed
From: Kees Cook <keescook@chromium.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Shuah Khan <shuah@kernel.org>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	linux-kselftest@vger.kernel.org,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Alexey Gladkov <gladkov.alexey@gmail.com>,
	Jann Horn <jannh@google.com>, Vito Caputo <vcaputo@pengaru.com>,
	Ingo Molnar <mingo@redhat.com>,
	juri.lelli@redhat.com, vincent.guittot@linaro.org,
	dietmar.eggemann@arm.com, Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>,
	mgorman@suse.de, bristot@redhat.com,
	Christian Brauner <christian.brauner@ubuntu.com>,
	amistry@google.com, Kenta.Tada@sony.com, legion@kernel.org,
	michael.weiss@aisec.fraunhofer.de, Michal Hocko <mhocko@suse.com>,
	deller@gmx.de, Qi Zheng <zhengqi.arch@bytedance.com>,
	me@tobin.cc, tycho@tycho.pizza,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
	Jens Axboe <axboe@kernel.dk>,
	metze@samba.org, Lai Jiangshan <laijs@linux.alibaba.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	ohoono.kwon@samsung.com, kaleshsingh@google.com,
	yifeifz2@illinois.edu, linux-arch@vger.kernel.org,
	vgupta@kernel.org,
	"Russell King (Oracle)" <linux@armlinux.org.uk>,
	Will Deacon <will@kernel.org>,
	guoren@kernel.org, bcain@codeaurora.org, monstr@monstr.eu,
	tsbogend@alpha.franken.de, nickhu@andestech.com,
	jonas@southpole.se, Michael Ellerman <mpe@ellerman.id.au>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	hca@linux.ibm.com, ysato@users.sourceforge.jp,
	davem@davemloft.net, chris@zankel.net,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] selftests: proc: Make sure wchan works when it exists
Date: Thu, 21 Oct 2021 20:35:07 -0700	[thread overview]
Message-ID: <202110212033.D533BAF@keescook> (raw)
In-Reply-To: <08669c29-a19e-44a8-a53e-acfa773d4680@www.fastmail.com>

On Thu, Oct 21, 2021 at 05:39:38PM -0700, Andy Lutomirski wrote:
> 
> 
> On Thu, Oct 21, 2021, at 1:12 PM, Kees Cook wrote:
> > On Thu, Oct 21, 2021 at 01:03:33PM -0700, Andy Lutomirski wrote:
> >> 
> >> 
> >> On Fri, Oct 8, 2021, at 4:55 PM, Kees Cook wrote:
> >> > This makes sure that wchan contains a sensible symbol when a process is
> >> > blocked. Specifically this calls the sleep() syscall, and expects the
> >> > architecture to have called schedule() from a function that has "sleep"
> >> > somewhere in its name. For example, on the architectures I tested
> >> > (x86_64, arm64, arm, mips, and powerpc) this is "hrtimer_nanosleep":
> >> 
> >> Is this really better than admitting that the whole mechanism is nonsense and disabling it?
> >> 
> >> We could have a fixed string for each task state and call it a day.
> >
> > I consider this to be "future work". In earlier discussions it came up,
> > but there wasn't an obvious clean cost-free way to do this, so instead
> > we're just fixing the broken corner and keeping the mostly working rest
> > of it while cleaning up the weird edges. :)
> 
> True, but we have the caveat that wchan is currently broken, so in some sense we have an easier time killing it now as compared to later.  But if we don't have a fully-fleshed-out idea for how to kill it, then I'm fine with waiting.

It's not actually that broken. Only ORC was fully broken, so all the
other architectures (and non-ORC x86) have been fine. But given the
method of fixing ORC vs wchan, it turns out we could further clean up
the other architectures. But yes, no real plan to remove it, but the
current series fixes things pretty well. :)

-Kees

> 
> >
> > -- 
> > Kees Cook

-- 
Kees Cook

      reply	other threads:[~2021-10-22  3:35 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-08 23:55 [PATCH] selftests: proc: Make sure wchan works when it exists Kees Cook
2021-10-09 12:52 ` Alexey Dobriyan
2021-10-11 17:42   ` Kees Cook
2021-10-21 17:09 ` Kees Cook
2021-10-21 19:30   ` Peter Zijlstra
2021-10-21 20:10     ` Kees Cook
2021-10-21 20:03 ` Andy Lutomirski
2021-10-21 20:12   ` Kees Cook
2021-10-22  0:39     ` Andy Lutomirski
2021-10-22  3:35       ` Kees Cook [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=202110212033.D533BAF@keescook \
    --to=keescook@chromium.org \
    --cc=Kenta.Tada@sony.com \
    --cc=adobriyan@gmail.com \
    --cc=akpm@linux-foundation.org \
    --cc=amistry@google.com \
    --cc=axboe@kernel.dk \
    --cc=bcain@codeaurora.org \
    --cc=bp@alien8.de \
    --cc=bristot@redhat.com \
    --cc=bsegall@google.com \
    --cc=chris@zankel.net \
    --cc=christian.brauner@ubuntu.com \
    --cc=dave.hansen@linux.intel.com \
    --cc=davem@davemloft.net \
    --cc=deller@gmx.de \
    --cc=dietmar.eggemann@arm.com \
    --cc=ebiederm@xmission.com \
    --cc=gladkov.alexey@gmail.com \
    --cc=guoren@kernel.org \
    --cc=hca@linux.ibm.com \
    --cc=hpa@zytor.com \
    --cc=jannh@google.com \
    --cc=jonas@southpole.se \
    --cc=jpoimboe@redhat.com \
    --cc=juri.lelli@redhat.com \
    --cc=kaleshsingh@google.com \
    --cc=laijs@linux.alibaba.com \
    --cc=legion@kernel.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-hardening@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=linux@armlinux.org.uk \
    --cc=luto@kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=me@tobin.cc \
    --cc=metze@samba.org \
    --cc=mgorman@suse.de \
    --cc=mhocko@suse.com \
    --cc=michael.weiss@aisec.fraunhofer.de \
    --cc=mingo@redhat.com \
    --cc=monstr@monstr.eu \
    --cc=mpe@ellerman.id.au \
    --cc=nickhu@andestech.com \
    --cc=ohoono.kwon@samsung.com \
    --cc=paul.walmsley@sifive.com \
    --cc=peterz@infradead.org \
    --cc=rostedt@goodmis.org \
    --cc=shuah@kernel.org \
    --cc=tglx@linutronix.de \
    --cc=tsbogend@alpha.franken.de \
    --cc=tycho@tycho.pizza \
    --cc=vcaputo@pengaru.com \
    --cc=vgupta@kernel.org \
    --cc=vincent.guittot@linaro.org \
    --cc=will@kernel.org \
    --cc=yifeifz2@illinois.edu \
    --cc=ysato@users.sourceforge.jp \
    --cc=zhengqi.arch@bytedance.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.