From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 7 May 2008 11:14:04 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH] more ZERO_PAGE handling ( was 2.6.24 regression: deadlock on coredump of big process) Message-Id: <20080507111404.871b8990.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20080430061125.GF27652@wotan.suse.de> References: <4815E932.1040903@cybernetics.com> <20080429100048.3e78b1ba.kamezawa.hiroyu@jp.fujitsu.com> <48172C72.1000501@cybernetics.com> <20080430132516.28f1ee0c.kamezawa.hiroyu@jp.fujitsu.com> <4817FDA5.1040702@kolumbus.fi> <20080430141738.e6b80d4b.kamezawa.hiroyu@jp.fujitsu.com> <20080430051932.GD27652@wotan.suse.de> <20080430143542.2dcf745a.kamezawa.hiroyu@jp.fujitsu.com> <20080430061125.GF27652@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Mika =?UTF-8?B?UGVudHRpbMOk?= , Tony Battersby , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton List-ID: On Wed, 30 Apr 2008 08:11:25 +0200 Nick Piggin wrote: > > pte = *ptep; > > - if (!pte_present(pte)) > > + if (!pte_present(pte)) { > > + if (!(flags & FOLL_WRITE) && pte_none(pte)) { > > + pte_unmap_unlock(ptep, ptl); > > + goto null_or_zeropage; > > + } > > goto unlock; > > + } > > Just a small nitpick: I guess you don't need this FOLL_WRITE test because > null_or_zeropage will test FOLL_ANON which implies !FOLL_WRITE. It should give > slightly smaller code. > > Otherwise, looks good to me: > Hmm, but do_execve() -> copy_strings() -> get_arg_page() -> get_user_pages() can do write-page-fault in ANON (and it's a valid ops.) So, I think it's safe not to remove FOLL_WRITE check here. Thanks, -Kame -- 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