Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755306AbaDTC2o (ORCPT ); Sat, 19 Apr 2014 22:28:44 -0400 Received: from g2t2353.austin.hp.com ([15.217.128.52]:57917 "EHLO g2t2353.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755234AbaDTC0v (ORCPT ); Sat, 19 Apr 2014 22:26:51 -0400 From: Davidlohr Bueso To: akpm@linux-foundation.org Cc: zeus@gnu.org, aswin@hp.com, davidlohr@hp.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vineet Gupta Subject: [PATCH 4/6] arc: call find_vma with the mmap_sem held Date: Sat, 19 Apr 2014 19:26:29 -0700 Message-Id: <1397960791-16320-5-git-send-email-davidlohr@hp.com> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1397960791-16320-1-git-send-email-davidlohr@hp.com> References: <1397960791-16320-1-git-send-email-davidlohr@hp.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Performing vma lookups without taking the mm->mmap_sem is asking for trouble. While doing the search, the vma in question can be modified or even removed before returning to the caller. Take the lock (shared) in order to avoid races while iterating through the vmacache and/or rbtree. This patch is completely *untested*. Signed-off-by: Davidlohr Bueso Cc: Vineet Gupta --- arch/arc/kernel/troubleshoot.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/arc/kernel/troubleshoot.c b/arch/arc/kernel/troubleshoot.c index 73a7450..3a5a5c1 100644 --- a/arch/arc/kernel/troubleshoot.c +++ b/arch/arc/kernel/troubleshoot.c @@ -90,7 +90,7 @@ static void show_faulting_vma(unsigned long address, char *buf) /* can't use print_vma_addr() yet as it doesn't check for * non-inclusive vma */ - + down_read(¤t->active_mm->mmap_sem); vma = find_vma(current->active_mm, address); /* check against the find_vma( ) behaviour which returns the next VMA @@ -110,9 +110,10 @@ static void show_faulting_vma(unsigned long address, char *buf) vma->vm_start < TASK_UNMAPPED_BASE ? address : address - vma->vm_start, nm, vma->vm_start, vma->vm_end); - } else { + } else pr_info(" @No matching VMA found\n"); - } + + up_read(¤t->active_mm->mmap_sem); } static void show_ecr_verbose(struct pt_regs *regs) -- 1.8.1.4 -- 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/