Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755483Ab0GHJf2 (ORCPT ); Thu, 8 Jul 2010 05:35:28 -0400 Received: from casper.infradead.org ([85.118.1.10]:59252 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753807Ab0GHJf1 convert rfc822-to-8bit (ORCPT ); Thu, 8 Jul 2010 05:35:27 -0400 Subject: Re: FYI: mmap_sem OOM patch From: Peter Zijlstra To: KOSAKI Motohiro Cc: Michel Lespinasse , linux-mm , LKML , Divyesh Shah In-Reply-To: <20100708182134.CD3F.A69D9226@jp.fujitsu.com> References: <20100707231134.GA26555@google.com> <1278579768.1900.14.camel@laptop> <20100708182134.CD3F.A69D9226@jp.fujitsu.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Thu, 08 Jul 2010 11:35:17 +0200 Message-ID: <1278581717.1900.20.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1288 Lines: 34 On Thu, 2010-07-08 at 18:24 +0900, KOSAKI Motohiro wrote: > > On Wed, 2010-07-07 at 16:11 -0700, Michel Lespinasse wrote: > > > > > diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c > > > index f627779..4b3a1c7 100644 > > > --- a/arch/x86/mm/fault.c > > > +++ b/arch/x86/mm/fault.c > > > @@ -1062,7 +1062,10 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code) > > > bad_area_nosemaphore(regs, error_code, address); > > > return; > > > } > > > - down_read(&mm->mmap_sem); > > > + if (test_thread_flag(TIF_MEMDIE)) > > > + down_read_unfair(&mm->mmap_sem); > > > + else > > > + down_read(&mm->mmap_sem); > > > } else { > > > /* > > > * The above down_read_trylock() might have succeeded in > > > > I still think adding that _unfair interface is asking for trouble. > > Can you please explain trouble that you worry? Why do we need to keep > thread fairness when OOM case? Just the whole concept of the unfair thing offends me ;-) I didn't really look at the particular application in this case. -- 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/