From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933253AbYHRTbn (ORCPT ); Mon, 18 Aug 2008 15:31:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764522AbYHRTas (ORCPT ); Mon, 18 Aug 2008 15:30:48 -0400 Received: from ns2.suse.de ([195.135.220.15]:40924 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932309AbYHRTaq (ORCPT ); Mon, 18 Aug 2008 15:30:46 -0400 Date: Mon, 18 Aug 2008 12:19:48 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org, jejb@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , Willy Tarreau , Rodrigo Rubira Branco , Jake Edge , Eugene Teo , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, KOSAKI Motohiro Subject: [patch 15/49] mlock() fix return values Message-ID: <20080818191948.GP10350@suse.de> References: <20080818191012.663450219@mini.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename="mlock-fix-return-values.patch" In-Reply-To: <20080818191834.GA10350@suse.de> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.25-stable review patch. If anyone has any objections, please let us know. ------------------ From: KOSAKI Motohiro commit a477097d9c37c1cf289c7f0257dffcfa42d50197 upstream Halesh says: Please find the below testcase provide to test mlock. Test Case : =========================== #include #include #include #include #include #include #include #include #include int main(void) { int fd,ret, i = 0; char *addr, *addr1 = NULL; unsigned int page_size; struct rlimit rlim; if (0 != geteuid()) { printf("Execute this pgm as root\n"); exit(1); } /* create a file */ if ((fd = open("mmap_test.c",O_RDWR|O_CREAT,0755)) == -1) { printf("cant create test file\n"); exit(1); } page_size = sysconf(_SC_PAGE_SIZE); /* set the MEMLOCK limit */ rlim.rlim_cur = 2000; rlim.rlim_max = 2000; if ((ret = setrlimit(RLIMIT_MEMLOCK,&rlim)) != 0) { printf("Cant change limit values\n"); exit(1); } addr = 0; while (1) { /* map a page into memory each time*/ if ((addr = (char *) mmap(addr,page_size, PROT_READ | PROT_WRITE,MAP_SHARED,fd,0)) == MAP_FAILED) { printf("cant do mmap on file\n"); exit(1); } if (0 == i) addr1 = addr; i++; errno = 0; /* lock the mapped memory pagewise*/ if ((ret = mlock((char *)addr, 1500)) == -1) { printf("errno value is %d\n", errno); printf("cant lock maped region\n"); exit(1); } addr = addr + page_size; } } ====================================================== This testcase results in an mlock() failure with errno 14 that is EFAULT, but it has nowhere been specified that mlock() will return EFAULT. When I tested the same on older kernels like 2.6.18, I got the correct result i.e errno 12 (ENOMEM). I think in source code mlock(2), setting errno ENOMEM has been missed in do_mlock() , on mlock_fixup() failure. SUSv3 requires the following behavior frmo mlock(2). [ENOMEM] Some or all of the address range specified by the addr and len arguments does not correspond to valid mapped pages in the address space of the process. [EAGAIN] Some or all of the memory identified by the operation could not be locked when the call was made. This rule isn't so nice and slighly strange. but many people think POSIX/SUS compliance is important. Reported-by: Halesh Sadashiv Tested-by: Halesh Sadashiv Signed-off-by: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/memory.c | 16 +++++++++++++--- mm/mlock.c | 2 -- 2 files changed, 13 insertions(+), 5 deletions(-) --- a/mm/memory.c +++ b/mm/memory.c @@ -2618,16 +2618,26 @@ int make_pages_present(unsigned long add vma = find_vma(current->mm, addr); if (!vma) - return -1; + return -ENOMEM; write = (vma->vm_flags & VM_WRITE) != 0; BUG_ON(addr >= end); BUG_ON(end > vma->vm_end); len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE; ret = get_user_pages(current, current->mm, addr, len, write, 0, NULL, NULL); - if (ret < 0) + if (ret < 0) { + /* + SUS require strange return value to mlock + - invalid addr generate to ENOMEM. + - out of memory should generate EAGAIN. + */ + if (ret == -EFAULT) + ret = -ENOMEM; + else if (ret == -ENOMEM) + ret = -EAGAIN; return ret; - return ret == len ? 0 : -1; + } + return ret == len ? 0 : -ENOMEM; } #if !defined(__HAVE_ARCH_GATE_AREA) --- a/mm/mlock.c +++ b/mm/mlock.c @@ -78,8 +78,6 @@ success: mm->locked_vm -= pages; out: - if (ret == -ENOMEM) - ret = -EAGAIN; return ret; } --