From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f54.google.com (mail-wg0-f54.google.com [74.125.82.54]) by kanga.kvack.org (Postfix) with ESMTP id AC8626B0032 for ; Sat, 18 Apr 2015 17:57:29 -0400 (EDT) Received: by wgyo15 with SMTP id o15so144288418wgy.2 for ; Sat, 18 Apr 2015 14:57:29 -0700 (PDT) Received: from kirsi1.inet.fi (mta-out1.inet.fi. [62.71.2.227]) by mx.google.com with ESMTP id w20si25075271wjr.194.2015.04.18.14.57.27 for ; Sat, 18 Apr 2015 14:57:28 -0700 (PDT) Date: Sun, 19 Apr 2015 00:56:56 +0300 From: "Kirill A. Shutemov" Subject: Re: kernel BUG at mm/swap.c:134! - page dumped because: VM_BUG_ON_PAGE(page_mapcount(page) != 0) Message-ID: <20150418215656.GA13928@node.dhcp.inet.fi> References: <20150418205656.GA7972@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Linus Torvalds , Borislav Petkov Cc: Naoya Horiguchi , Michal Hocko , Andrew Morton , x86-ml , linux-mm , Andrea Arcangeli , Hugh Dickins On Sat, Apr 18, 2015 at 05:27:49PM -0400, Linus Torvalds wrote: > On Sat, Apr 18, 2015 at 4:56 PM, Borislav Petkov wrote: > > > > so I'm running some intermediate state of linus/master + tip/master from > > Thursday and probably I shouldn't be even taking such splat seriously > > and wait until 4.1-rc1 has been done but let me report it just in case > > so that it is out there, in case someone else sees it too. > > > > I don't have a reproducer yet except the fact that it happened twice > > already, the second time while watching the new Star Wars teaser on > > youtube (current->comm is "AudioThread" probably from chrome, as shown > > in the splat below). I would guess it's related to sound: the most common source of PTE-mapeed compund pages into userspace. > Hmm. The only recent commit in this area seems to be 822fc61367f0 > ("mm: don't call __page_cache_release for hugetlb") although I don't > see why it would cause anything like that. But it changes code that > has been stable for many years, which makes me wonder how valid it is > (__put_compound_page() has been unchanged since 2011, and now suddenly > it grew that "!PageHuge()" test). > > So quite frankly, I'd almost suggest changing that > > if (!PageHuge(page)) > __page_cache_release(page); > > back to the old unconditional __page_cache_release(page), and maybe add a single > > WARN_ON_ONCE(PageHuge(page)); > > just to see if that condition actually happens. The new comment says > it shouldn't happen and that the change shouldn't matter, but... > > Of course, your recent BUG_ON may well be entirely unrelated to this > change in mm/swap.c, but it *is* in kind of the same area, and the > timing would match too... Andrea has already seen the bug and pointed to 8d63d99a5dfb as possible cause. I don't see why the commit could broke anything, but it worth trying to revert and test. Borislav, could you try? > --- > [115258.861335] page:ffffea0010a15040 count:0 mapcount:1 mapping: > (null) index:0x0 > [115258.869511] flags: 0x8000000000008014(referenced|dirty|tail) > [115258.874159] page dumped because: VM_BUG_ON_PAGE(page_mapcount(page) != 0) > [115258.874179] kernel BUG at mm/swap.c:134! > [115258.874262] RIP: put_compound_page+0x3b9/0x480 > > -- > 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 -- 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