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Date:   Wed, 24 May 2023 22:00:14 +0200
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     "Helge Deller" <deller@gmx.de>,
        "Russell King" <linux@armlinux.org.uk>,
        "Dinh Nguyen" <dinguyen@kernel.org>, linux-kernel@vger.kernel.org,
        linux-parisc@vger.kernel.org
Cc:     linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/3] arm: Fix flush_dcache_page() for usage from irq context
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On Wed, May 24, 2023, at 17:26, Helge Deller wrote:
> Since at least kernel 6.1, flush_dcache_page() is called with IRQs
> disabled, e.g. from aio_complete().
>
> But the current implementation for flush_dcache_page() on ARM
> unintentionally re-enables IRQs, which may lead to deadlocks.
>
> Fix it by using xa_lock_irqsave() and xa_unlock_irqrestore()
> for the flush_dcache_mmap_*lock() macros instead.
>
> Cc: Russell King (Oracle) <linux@armlinux.org.uk>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: linux-arm-kernel@lists.infradead.org
> Signed-off-by: Helge Deller <deller@gmx.de>

Cc: stable@vger.kernel.org
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

From what I can tell, the behavior in aio_complete has been
there for over 10 years, since 21b40200cfe96 ("aio: use
flush_dcache_page()"). Others may have done the same already
back then.

I also see you sent patches for nios2 and parisc, but not
for csky, which appears to need the same thing.

     Arnd