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From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Peter Zijlstra <peterz@infradead.org>
Cc: keescook@chromium.org, jannh@google.com,
	linux-kernel@vger.kernel.org, vcaputo@pengaru.com,
	mingo@redhat.com, juri.lelli@redhat.com,
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	rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
	bristot@redhat.com, akpm@linux-foundation.org,
	christian.brauner@ubuntu.com, amistry@google.com,
	Kenta.Tada@sony.com, legion@kernel.org,
	michael.weiss@aisec.fraunhofer.de, mhocko@suse.com,
	deller@gmx.de, zhengqi.arch@bytedance.com, me@tobin.cc,
	tycho@tycho.pizza, tglx@linutronix.de, bp@alien8.de,
	hpa@zytor.com, mark.rutland@arm.com, axboe@kernel.dk,
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	yifeifz2@illinois.edu, jpoimboe@redhat.com,
	linux-hardening@vger.kernel.org, linux-arch@vger.kernel.org,
	vgupta@kernel.org, will@kernel.org, guoren@kernel.org,
	bcain@codeaurora.org, monstr@monstr.eu,
	tsbogend@alpha.franken.de, nickhu@andestech.com,
	jonas@southpole.se, mpe@ellerman.id.au, paul.walmsley@sifive.com,
	hca@linux.ibm.com, ysato@users.sourceforge.jp,
	davem@davemloft.net, chris@zankel.net
Subject: Re: [PATCH 0/7] wchan: Fix wchan support
Date: Thu, 14 Oct 2021 13:02:34 +0100	[thread overview]
Message-ID: <YWgcWnbsvI1rbvEj@shell.armlinux.org.uk> (raw)
In-Reply-To: <20211008111527.438276127@infradead.org>

On Fri, Oct 08, 2021 at 01:15:27PM +0200, Peter Zijlstra wrote:
> Hi,
> 
> This fixes up wchan which is various degrees of broken across the
> architectures.
> 
> Patch 4 fixes wchan for x86, which has been returning 0 for the past many
> releases.
> 
> Patch 5 fixes the fundamental race against scheduling.
> 
> Patch 6 deletes a lot and makes STACKTRACE unconditional
> 
> patch 7 fixes up a few STACKTRACE arch oddities
> 
> 0day says all builds are good, so it must be perfect :-) I'm planning on
> queueing up at least the first 5 patches, but I'm hoping the last two patches
> can be too.
> 
> Also available here:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/wchan

These patches introduce a regression on ARM. Whereas before, I have
/proc/*/wchan populated with non-zero values, with these patches they
_all_ contain "0":

root@clearfog21:~# cat /proc/*/wchan
0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000root@clearfog21:~#

I'll try to investigate what is going on later today.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

  parent reply	other threads:[~2021-10-14 12:03 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-08 11:15 [PATCH 0/7] wchan: Fix wchan support Peter Zijlstra
2021-10-08 11:15 ` [PATCH 1/7] Revert "proc/wchan: use printk format instead of lookup_symbol_name()" Peter Zijlstra
2021-10-15  9:45   ` [tip: sched/core] " tip-bot2 for Kees Cook
2021-10-08 11:15 ` [PATCH 2/7] leaking_addresses: Always print a trailing newline Peter Zijlstra
2021-10-15  9:45   ` [tip: sched/core] " tip-bot2 for Kees Cook
2021-10-08 11:15 ` [PATCH 3/7] proc: Use task_is_running() for wchan in /proc/$pid/stat Peter Zijlstra
2021-10-15  9:45   ` [tip: sched/core] " tip-bot2 for Kees Cook
2021-10-08 11:15 ` [PATCH 4/7] x86: Fix get_wchan() to support the ORC unwinder Peter Zijlstra
2021-10-15  9:45   ` [tip: sched/core] " tip-bot2 for Qi Zheng
2021-10-08 11:15 ` [PATCH 5/7] sched: Add wrapper for get_wchan() to keep task blocked Peter Zijlstra
2021-10-08 11:26   ` Geert Uytterhoeven
2021-10-08 12:45   ` Mark Rutland
2021-10-14 10:46   ` Russell King (Oracle)
2021-10-15  9:45   ` [tip: sched/core] " tip-bot2 for Kees Cook
2021-10-08 11:15 ` [PATCH 6/7] arch: __get_wchan || STACKTRACE_SUPPORT Peter Zijlstra
2021-10-08 12:40   ` Mark Rutland
2021-10-08 13:45     ` Peter Zijlstra
2021-10-08 16:17       ` Josh Poimboeuf
2021-10-14 18:07         ` Mark Rutland
2021-10-14 18:41           ` Josh Poimboeuf
2021-10-14 18:03       ` Mark Rutland
2021-10-14 18:48         ` Josh Poimboeuf
2021-10-14 11:07   ` Russell King (Oracle)
2021-10-08 11:15 ` [PATCH 7/7] arch: Fix STACKTRACE_SUPPORT Peter Zijlstra
2021-10-08 12:52   ` Mark Rutland
2021-10-09  9:36   ` Guo Ren
2021-10-14 12:02 ` Russell King (Oracle) [this message]
2021-10-14 13:38   ` [PATCH 0/7] wchan: Fix wchan support Russell King (Oracle)
2021-10-14 19:51     ` Josh Poimboeuf

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