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Date:   Mon, 9 Jul 2018 16:49:25 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Alexey Brodkin <Alexey.Brodkin@synopsys.com>
Cc:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
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        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "greg@kroah.com" <greg@kroah.com>,
        "will.deacon@arm.com" <will.deacon@arm.com>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        "David.Laight@ACULAB.COM" <David.Laight@ACULAB.COM>,
        "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
        "geert@linux-m68k.org" <geert@linux-m68k.org>
Subject: Re: [PATCH v3] devres: Explicitly align datai[] to 64-bit
Message-ID: <20180709144925.GU2476@hirez.programming.kicks-ass.net>
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On Mon, Jul 09, 2018 at 02:33:26PM +0000, Alexey Brodkin wrote:
> > In fact, since alloc_dr() uses kmalloc() to allocate the entire thing,
> > it is impossible to guarantee a larger alignment than kmalloc does.
> 
> Well but 4-bytes [which is critical for atomic64_t] should be much less
> than a sane cache line length so above should work.

AFAICT ARCH_KMALLOC_MINALIGN ends up being 4 on x86_32 (it doesn't
define ARCH_DMA_MINALIGN and doesn't seem to otherwise override the
thing).

So unconditionally setting the alignment of devres::data to 8 seems
broken.