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Date: Mon, 23 Jan 2017 14:54:28 -0800 (PST)
From: David Rientjes <rientjes@google.com>
Subject: Re: [PATCH] mm: ensure alloc_flags in slow path are initialized
In-Reply-To: <20170123121649.3180300-1-arnd@arndb.de>
Message-ID: <alpine.DEB.2.10.1701231454170.126378@chino.kir.corp.google.com>
References: <20170123121649.3180300-1-arnd@arndb.de>
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Sender: owner-linux-mm@kvack.org
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To: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Morton <akpm@linux-foundation.org>, Vlastimil Babka <vbabka@suse.cz>, Mel Gorman <mgorman@techsingularity.net>, Michal Hocko <mhocko@suse.com>, Johannes Weiner <hannes@cmpxchg.org>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org

On Mon, 23 Jan 2017, Arnd Bergmann wrote:

> The __alloc_pages_slowpath() has gotten rather complex and gcc
> is no longer able to follow the gotos and prove that the
> alloc_flags variable is initialized at the time it is used:
> 
> mm/page_alloc.c: In function '__alloc_pages_slowpath':
> mm/page_alloc.c:3565:15: error: 'alloc_flags' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> 
> To be honest, I can't figure that out either, maybe it is or
> maybe not, but moving the existing initialization up a little
> higher looks safe and makes it obvious to both me and gcc that
> the initialization comes before the first use.
> 
> Fixes: 74eaa4a97e8e ("mm: consolidate GFP_NOFAIL checks in the allocator slowpath")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Acked-by: David Rientjes <rientjes@google.com>

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