From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f50.google.com (mail-wm0-f50.google.com [74.125.82.50]) by kanga.kvack.org (Postfix) with ESMTP id 49E4D6B0009 for ; Mon, 18 Jan 2016 18:03:27 -0500 (EST) Received: by mail-wm0-f50.google.com with SMTP id l65so117239934wmf.1 for ; Mon, 18 Jan 2016 15:03:27 -0800 (PST) Received: from mail-wm0-x230.google.com (mail-wm0-x230.google.com. [2a00:1450:400c:c09::230]) by mx.google.com with ESMTPS id 5si28562714wmx.6.2016.01.18.15.03.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 18 Jan 2016 15:03:26 -0800 (PST) Received: by mail-wm0-x230.google.com with SMTP id b14so144836355wmb.1 for ; Mon, 18 Jan 2016 15:03:26 -0800 (PST) Date: Tue, 19 Jan 2016 01:03:24 +0200 From: "Kirill A. Shutemov" Subject: Re: [PATCH] mm: avoid uninitialized variable in tracepoint Message-ID: <20160118230324.GF14531@node.shutemov.name> References: <4117363.Ys1FTDH7Wz@wuerfel> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4117363.Ys1FTDH7Wz@wuerfel> Sender: owner-linux-mm@kvack.org List-ID: To: Arnd Bergmann , Andrew Morton Cc: Ebru Akagunduz , dan.carpenter@oracle.com, linux-mm@kvack.org, Linus Torvalds , "Kirill A. Shutemov" , Rik van Riel , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org On Mon, Jan 18, 2016 at 09:50:26PM +0100, Arnd Bergmann wrote: > A newly added tracepoint in the hugepage code uses a variable in the > error handling that is not initialized at that point: > > include/trace/events/huge_memory.h:81:230: error: 'isolated' may be used uninitialized in this function [-Werror=maybe-uninitialized] > > The result is relatively harmless, as the trace data will in rare > cases contain incorrect data. > > This works around the problem by adding an explicit initialization. > > Signed-off-by: Arnd Bergmann > Fixes: 7d2eba0557c1 ("mm: add tracepoint for scanning pages") There's the same patch in mm tree, but it got lost on the way to Linus' tree: https://ozlabs.org/~akpm/mmots/broken-out/mm-make-optimistic-check-for-swapin-readahead-fix.patch Andrew? > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index b2db98136af9..bb3b763b1829 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2320,7 +2320,7 @@ static void collapse_huge_page(struct mm_struct *mm, > pgtable_t pgtable; > struct page *new_page; > spinlock_t *pmd_ptl, *pte_ptl; > - int isolated, result = 0; > + int isolated = 0, result = 0; > unsigned long hstart, hend; > struct mem_cgroup *memcg; > unsigned long mmun_start; /* For mmu_notifiers */ > -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org