linux-kernel - Re: [BACKPORT 4.4.y 21/25] arm64: traps: disable irq in die()

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Date:   Tue, 26 Mar 2019 10:31:09 +0900
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     stable@...r.kernel.org, Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Mark Rutland <mark.rutland@....com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Marc Zyngier <marc.zyngier@....com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Qiao Zhou <qiaozhou@...micro.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [BACKPORT 4.4.y 21/25] arm64: traps: disable irq in die()

On Fri, Mar 22, 2019 at 04:44:12PM +0100, Arnd Bergmann wrote:
> From: Qiao Zhou <qiaozhou@...micro.com>
> 
> In current die(), the irq is disabled for __die() handle, not
> including the possible panic() handling. Since the log in __die()
> can take several hundreds ms, new irq might come and interrupt
> current die().
> 
> If the process calling die() holds some critical resource, and some
> other process scheduled later also needs it, then it would deadlock.
> The first panic will not be executed.
> 
> So here disable irq for the whole flow of die().
> 
> Signed-off-by: Qiao Zhou <qiaozhou@...micro.com>
> Signed-off-by: Will Deacon <will.deacon@....com>
> (cherry picked from commit 6f44a0bacb79a03972c83759711832b382b1b8ac)
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  arch/arm64/kernel/traps.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)

also added to 4.9.y