From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx153.postini.com [74.125.245.153]) by kanga.kvack.org (Postfix) with SMTP id C43B16B0033 for ; Tue, 23 Apr 2013 16:25:24 -0400 (EDT) Date: Tue, 23 Apr 2013 13:25:22 -0700 From: Andrew Morton Subject: Re: [Bug 56881] New: MAP_HUGETLB mmap fails for certain sizes Message-Id: <20130423132522.042fa8d27668bbca6a410a92@linux-foundation.org> In-Reply-To: References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: bugzilla-daemon@bugzilla.kernel.org, iceman_dvd@yahoo.com (switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface). On Sat, 20 Apr 2013 03:00:30 +0000 (UTC) bugzilla-daemon@bugzilla.kernel.org wrote: > https://bugzilla.kernel.org/show_bug.cgi?id=56881 > > Summary: MAP_HUGETLB mmap fails for certain sizes > Product: Memory Management > Version: 2.5 > Kernel Version: 3.5.0-27 Thanks. It's a post-3.4 regression, testcase included. Does someone want to take a look, please? > Platform: All > OS/Version: Linux > Tree: Mainline > Status: NEW > Severity: high > Priority: P1 > Component: Other > AssignedTo: akpm@linux-foundation.org > ReportedBy: iceman_dvd@yahoo.com > Regression: No > > > This is on an Ubuntu 12.10 desktop, but the same issue has been found on 12.04 > with 3.5.0 kernel. > See the sample program. An allocation with MAP_HUGETLB consistently fails with > certain sizes, while it succeeds with others. > The allocation sizes are well below the number of free huge pages. > > $ uname -a Linux davide-lnx2 3.5.0-27-generic #46-Ubuntu SMP Mon Mar 25 > 19:58:17 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux > > > # echo 100 > /proc/sys/vm/nr_hugepages > > # cat /proc/meminfo > ... > AnonHugePages: 0 kB > HugePages_Total: 100 > HugePages_Free: 100 > HugePages_Rsvd: 0 > HugePages_Surp: 0 > Hugepagesize: 2048 kB > > > $ ./mmappu $((5 * 2 * 1024 * 1024 - 4096)) > size=10481664 0x9ff000 > hugepage mmap: Invalid argument > > > $ ./mmappu $((5 * 2 * 1024 * 1024 - 4095)) > size=10481665 0x9ff001 > OK! > > > It seems the trigger point is a normal page size. > The same binary works flawlessly in previous kernels. -- 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