Re: [PATCH AUTOSEL 5.9 27/39] sched/idle: Fix arch_cpu_idle() vs tracing
From: Peter Zijlstra <peterz@infradead.org>
Date: 2020-12-03 17:12:06
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linux-alpha, linux-arm-kernel, linux-mips, linux-riscv, linux-s390, linux-sh, linux-um, lkml, sparclinux, stable
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:quoted
From: Peter Zijlstra <peterz@infradead.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@linux.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Link: https://lkml.kernel.org/r/20201120114925.594122626@infradead.org Signed-off-by: Sasha Levin <sashal@kernel.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.