linux-kernel - Re: [PATCH AUTOSEL 5.9 27/39] sched/idle: Fix arch_cpu

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Message-ID: <20201213141029.GQ643756@sasha-vm>
Date:   Sun, 13 Dec 2020 09:10:29 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Heiko Carstens <hca@...ux.ibm.com>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, Sven Schnelle <svens@...ux.ibm.com>,
        Mark Rutland <mark.rutland@....com>,
        linux-alpha@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-csky@...r.kernel.org, uclinux-h8-devel@...ts.sourceforge.jp,
        linux-hexagon@...r.kernel.org, linux-ia64@...r.kernel.org,
        linux-mips@...r.kernel.org, openrisc@...ts.librecores.org,
        linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
        linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
        linux-um@...ts.infradead.org
Subject: Re: [PATCH AUTOSEL 5.9 27/39] sched/idle: Fix arch_cpu_idle() vs
 tracing

On Thu, Dec 03, 2020 at 06:10:15PM +0100, Peter Zijlstra wrote:
>On Thu, Dec 03, 2020 at 03:54:42PM +0100, Heiko Carstens wrote:
>> On Thu, Dec 03, 2020 at 08:28:21AM -0500, Sasha Levin wrote:
>> > From: Peter Zijlstra <peterz@...radead.org>
>> >
>> > [ Upstream commit 58c644ba512cfbc2e39b758dd979edd1d6d00e27 ]
>> >
>> > We call arch_cpu_idle() with RCU disabled, but then use
>> > local_irq_{en,dis}able(), which invokes tracing, which relies on RCU.
>> >
>> > Switch all arch_cpu_idle() implementations to use
>> > raw_local_irq_{en,dis}able() and carefully manage the
>> > lockdep,rcu,tracing state like we do in entry.
>> >
>> > (XXX: we really should change arch_cpu_idle() to not return with
>> > interrupts enabled)
>> >
>> > Reported-by: Sven Schnelle <svens@...ux.ibm.com>
>> > Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
>> > Reviewed-by: Mark Rutland <mark.rutland@....com>
>> > Tested-by: Mark Rutland <mark.rutland@....com>
>> > Link: https://lkml.kernel.org/r/20201120114925.594122626@infradead.org
>> > Signed-off-by: Sasha Levin <sashal@...nel.org>
>>
>> This patch broke s390 irq state tracing. A patch to fix this is
>> scheduled to be merged upstream today (hopefully).
>> Therefore I think this patch should not yet go into 5.9 stable.
>
>Agreed.

I'll also grab b1cae1f84a0f ("s390: fix irq state tracing"). Thanks!

-- 
Thanks,
Sasha