From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id A63F38D0039 for ; Tue, 8 Mar 2011 10:59:48 -0500 (EST) From: Andrey Vagin 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> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Andrew Morton 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, 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org