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Message-ID: <8891277c7de92e93d3bfc409df95810ee6f103cd.camel@kernel.crashing.org>
Subject: Re: [PATCH] memblock: stop using implicit alignement to
 SMP_CACHE_BYTES
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Fri, 05 Oct 2018 13:25:38 +1000
In-Reply-To: <1538687224-17535-1-git-send-email-rppt@linux.vnet.ibm.com>
References: <1538687224-17535-1-git-send-email-rppt@linux.vnet.ibm.com>
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To: Mike Rapoport <rppt@linux.vnet.ibm.com>, linux-mm@kvack.org
Cc: linux-mips@linux-mips.org, Michal Hocko <mhocko@suse.com>, linux-ia64@vger.kernel.org, Catalin Marinas <catalin.marinas@arm.com>, Richard Weinberger <richard@nod.at>, Russell King <linux@armlinux.org.uk>, Ingo Molnar <mingo@redhat.com>, Geert Uytterhoeven <geert@linux-m68k.org>, Matt Turner <mattst88@gmail.com>, linux-um@lists.infradead.org, linux-m68k@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>, Guan Xuetao <gxt@pku.edu.cn>, linux-arm-kernel@lists.infradead.org, Chris Zankel <chris@zankel.net>, Michal Simek <monstr@monstr.eu>, Tony Luck <tony.luck@intel.com>, linux-kernel@vger.kernel.org, Paul Burton <paul.burton@mips.com>, linux-alpha@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>, linuxppc-dev@lists.ozlabs.org

On Fri, 2018-10-05 at 00:07 +0300, Mike Rapoport wrote:
> When a memblock allocation APIs are called with align = 0, the alignment is
> implicitly set to SMP_CACHE_BYTES.
> 
> Replace all such uses of memblock APIs with the 'align' parameter explicitly
> set to SMP_CACHE_BYTES and stop implicit alignment assignment in the
> memblock internal allocation functions.
> 
> For the case when memblock APIs are used via helper functions, e.g. like
> iommu_arena_new_node() in Alpha, the helper functions were detected with
> Coccinelle's help and then manually examined and updated where appropriate.
> 
> The direct memblock APIs users were updated using the semantic patch below:

What is the purpose of this ? It sounds rather counter-intuitive...

Ben.