From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id 5729F6B0194 for ; Thu, 14 May 2009 06:58:36 -0400 (EDT) Date: Thu, 14 May 2009 11:59:26 +0100 From: Mel Gorman Subject: Re: [Bugme-new] [Bug 13302] New: "bad pmd" on fork() of process with hugepage shared memory segments attached Message-ID: <20090514105926.GB11770@csn.ul.ie> References: <20090513130846.d463cc1e.akpm@linux-foundation.org> <20090514105326.GA11770@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20090514105326.GA11770@csn.ul.ie> Sender: owner-linux-mm@kvack.org To: starlight@binnacle.cx, Andrew Morton Cc: linux-mm@kvack.org, bugzilla-daemon@bugzilla.kernel.org, bugme-daemon@bugzilla.kernel.org, Adam Litke , Eric B Munson List-ID: On Thu, May 14, 2009 at 11:53:27AM +0100, Mel Gorman wrote: > On Wed, May 13, 2009 at 01:08:46PM -0700, Andrew Morton wrote: > > > > (switched to email. Please respond via emailed reply-to-all, not via the > > bugzilla web interface). > > > > (Please read this ^^^^ !) > > > > On Wed, 13 May 2009 19:54:10 GMT > > bugzilla-daemon@bugzilla.kernel.org wrote: > > > > > http://bugzilla.kernel.org/show_bug.cgi?id=13302 > > > > > > Summary: "bad pmd" on fork() of process with hugepage shared > > > memory segments attached > > > Product: Memory Management > > > Version: 2.5 > > > Kernel Version: 2.6.29.1 > > > Platform: All > > > OS/Version: Linux > > > Tree: Mainline > > > Status: NEW > > > Severity: normal > > > Priority: P1 > > > Component: Other > > > AssignedTo: akpm@linux-foundation.org > > > ReportedBy: starlight@binnacle.cx > > > Regression: Yes > > > > > > > > > Kernel reports "bad pmd" errors when process with hugepage > > > shared memory segments attached executes fork() system call. > > > Using vfork() avoids the issue. > > > > > > Bug also appears in RHEL5 2.6.18-128.1.6.el5 and causes > > > leakage of huge pages. > > > > > > Bug does not appear in RHEL4 2.6.9-78.0.13.ELsmp. > > > > > > See bug 12134 for an example of the errors reported > > > by 'dmesg'. > > > > > This seems familiar and I believe it couldn't be reproduced the last time > and then the problem reporter went away. We need a reproduction case so > I modified on of the libhugetlbfs tests to do what I think you described > above. However, it does not trigger the problem for me on x86 or x86-64 > running 2.6.29.1. > > starlight@binnacle.cz, can you try the reproduction steps on your system > please? If it reproduces, can you send me your .config please? If it > does not reproduce, can you look at the test program and tell me what > it's doing different to your reproduction case? > Another question on top of this. At any point, do you call madvise(MADV_WILLNEED), fadvise(FADV_WILLNEED) or readahead() on the share memory segment? -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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