linux-kernel - Re: [PATCH] mm, compaction: avoid uninitialized variable use

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Message-ID: <4247828.QFzDnOkjoa@wuerfel>
Date:	Thu, 12 May 2016 14:04:10 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Michal Hocko <mhocko@...nel.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mgorman@...hsingularity.net>,
	Vlastimil Babka <vbabka@...e.cz>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Taku Izumi <izumi.taku@...fujitsu.com>,
	Johannes Weiner <hannes@...xchg.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm, compaction: avoid uninitialized variable use

On Thursday 12 May 2016 08:16:36 Michal Hocko wrote:
> I think this would be slightly better than your proposal. Andrew, could
> you fold it into the original
> mm-compaction-simplify-__alloc_pages_direct_compact-feedback-interface.patch
> patch?
> ---
> From 434bc8b6f3787724327499998c4fe651e8ce5d68 Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@...e.com>
> Date: Thu, 12 May 2016 08:10:33 +0200
> Subject: [PATCH] mmotm:
>  mm-compaction-simplify-__alloc_pages_direct_compact-feedback-interface-fix
> 
> Arnd has reported the following compilation warning:
> mm/page_alloc.c: In function '__alloc_pages_nodemask':
> mm/page_alloc.c:3651:6: error: 'compact_result' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> 
> This should be a false positive TRANSPARENT_HUGEPAGE depends on COMPACTION
> so is_thp_gfp_mask shouldn't be true. GFP_TRANSHUGE is a bit tricky
> and somebody might be using this accidently. Make sure that compact_result
> is defined also for !CONFIG_COMPACT and set it to COMPACT_SKIPPED because
> the compaction was really withdrawn.
> 
> Reported-by: Arnd Bergmann <arnd@...db.de>
> Signed-off-by: Michal Hocko <mhocko@...e.com>
> 

Acked-by: Arnd Bergmann <arnd@...db.de>

Looks much nicer than my version.

	Arnd