Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755916Ab0GHJvZ (ORCPT ); Thu, 8 Jul 2010 05:51:25 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:44650 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752832Ab0GHJvX (ORCPT ); Thu, 8 Jul 2010 05:51:23 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: Peter Zijlstra Subject: Re: FYI: mmap_sem OOM patch Cc: kosaki.motohiro@jp.fujitsu.com, Michel Lespinasse , linux-mm , LKML , Divyesh Shah In-Reply-To: <1278581717.1900.20.camel@laptop> References: <20100708182134.CD3F.A69D9226@jp.fujitsu.com> <1278581717.1900.20.camel@laptop> Message-Id: <20100708184341.CD42.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Mailer: Becky! ver. 2.50.07 [ja] Date: Thu, 8 Jul 2010 18:51:20 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1465 Lines: 39 > 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. I see. Yup, I agree unfair thing concept is a bit ugly. If anyone have alternative idea, I agree to choose that thing. -- 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/