Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755478Ab1CHQA2 (ORCPT ); Tue, 8 Mar 2011 11:00:28 -0500 Received: from mailhub.sw.ru ([195.214.232.25]:36935 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754782Ab1CHQA1 (ORCPT ); Tue, 8 Mar 2011 11:00:27 -0500 From: Andrey Vagin To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Andrew Morton Subject: [PATCH] mm: handle mm_fault_error in kernel space (v2) Date: Tue, 8 Mar 2011 18:59:25 +0300 Message-Id: <1299599965-28995-1-git-send-email-avagin@openvz.org> X-Mailer: git-send-email 1.7.3.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1713 Lines: 49 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 --- arch/x86/mm/fault.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 7d90ceb..ffc7be1 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -828,6 +828,13 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code, 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| -- 1.7.1 -- 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/