Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031128AbbKEJ0a (ORCPT ); Thu, 5 Nov 2015 04:26:30 -0500 Received: from mail-wm0-f45.google.com ([74.125.82.45]:37235 "EHLO mail-wm0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030199AbbKEJ01 (ORCPT ); Thu, 5 Nov 2015 04:26:27 -0500 Date: Thu, 5 Nov 2015 11:26:22 +0200 From: "Kirill A. Shutemov" To: Hillf Danton Cc: "Kirill A. Shutemov" , Andrew Morton , Andrea Arcangeli , Hugh Dickins , Naoya Horiguchi , Sasha Levin , linux-kernel , linux-mm@kvack.org, "'Minchan Kim'" Subject: Re: [PATCH 3/4] thp: fix split vs. unmap race Message-ID: <20151105092622.GD7614@node.shutemov.name> References: <052401d116e0$c3ac0110$4b040330$@alibaba-inc.com> <052701d116e2$0437a2b0$0ca6e810$@alibaba-inc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <052701d116e2$0437a2b0$0ca6e810$@alibaba-inc.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1667 Lines: 51 On Wed, Nov 04, 2015 at 05:20:15PM +0800, Hillf Danton wrote: > > @@ -1135,20 +1135,12 @@ void do_page_add_anon_rmap(struct page *page, > > bool compound = flags & RMAP_COMPOUND; > > bool first; > > > > - if (PageTransCompound(page)) { > > + if (compound) { > > + atomic_t *mapcount; > > VM_BUG_ON_PAGE(!PageLocked(page), page); > > - if (compound) { > > - atomic_t *mapcount; > > - > > - VM_BUG_ON_PAGE(!PageTransHuge(page), page); > > - mapcount = compound_mapcount_ptr(page); > > - first = atomic_inc_and_test(mapcount); > > - } else { > > - /* Anon THP always mapped first with PMD */ > > - first = 0; > > - VM_BUG_ON_PAGE(!page_mapcount(page), page); > > - atomic_inc(&page->_mapcount); > > - } > > + VM_BUG_ON_PAGE(!PageTransHuge(page), page); > > + mapcount = compound_mapcount_ptr(page); > > + first = atomic_inc_and_test(mapcount); > > } else { > > VM_BUG_ON_PAGE(compound, page); > > Then this debug info is no longer needed. > > first = atomic_inc_and_test(&page->_mapcount); Right. diff --git a/mm/rmap.c b/mm/rmap.c index 0837487d3737..a9550b1f74cd 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1186,7 +1186,6 @@ void do_page_add_anon_rmap(struct page *page, mapcount = compound_mapcount_ptr(page); first = atomic_inc_and_test(mapcount); } else { - VM_BUG_ON_PAGE(compound, page); first = atomic_inc_and_test(&page->_mapcount); } -- Kirill A. Shutemov -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/