From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932394Ab1CVACF (ORCPT ); Mon, 21 Mar 2011 20:02:05 -0400 Received: from kroah.org ([198.145.64.141]:48929 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754882Ab1CUXNe (ORCPT ); Mon, 21 Mar 2011 19:13:34 -0400 X-Mailbox-Line: From gregkh@clark.kroah.org Mon Mar 21 16:10:51 2011 Message-Id: <20110321231051.357519073@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Mon, 21 Mar 2011 16:09:46 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Andrey Vagin , "H. Peter Anvin" , Ingo Molnar Subject: [06/44] x86/mm: Handle mm_fault_error() in kernel space In-Reply-To: <20110321231105.GA1744@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let us know. ------------------ From: Andrey Vagin commit f86268549f424f83b9eb0963989270e14fbfc3de upstream. mm_fault_error() should not execute oom-killer, if page fault occurs in kernel space. E.g. in copy_from_user()/copy_to_user(). This would happen if we find ourselves in OOM on a copy_to_user(), or a copy_from_user() which faults. Without this patch, the kernels hangs up in copy_from_user(), because OOM killer sends SIG_KILL to current process, but it can't handle a signal while in syscall, then the kernel returns to copy_from_user(), reexcute current command and provokes page_fault again. With this patch the kernel return -EFAULT from copy_from_user(). The code, which checks that page fault occurred in kernel space, has been copied from do_sigbus(). This situation is handled by the same way on powerpc, xtensa, tile, ... Signed-off-by: Andrey Vagin Signed-off-by: Andrew Morton Cc: "H. Peter Anvin" Cc: Linus Torvalds LKML-Reference: <201103092322.p29NMNPH001682@imap1.linux-foundation.org> Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/mm/fault.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -830,6 +830,13 @@ mm_fault_error(struct pt_regs *regs, uns unsigned long address, unsigned int fault) { if (fault & VM_FAULT_OOM) { + /* Kernel mode? Handle exceptions or die: */ + if (!(error_code & PF_USER)) { + up_read(¤t->mm->mmap_sem); + no_context(regs, error_code, address); + return; + } + out_of_memory(regs, error_code, address); } else { if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON))