Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755270AbaDTC2I (ORCPT ); Sat, 19 Apr 2014 22:28:08 -0400 Received: from g2t2353.austin.hp.com ([15.217.128.52]:57912 "EHLO g2t2353.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755201AbaDTC0s (ORCPT ); Sat, 19 Apr 2014 22:26:48 -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, Ralf Baechle , linux-mips@linux-mips.org Subject: [PATCH 3/6] mips: call find_vma with the mmap_sem held Date: Sat, 19 Apr 2014 19:26:28 -0700 Message-Id: <1397960791-16320-4-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 (exclusively) in order to avoid races while iterating through the vmacache and/or rbtree. Updates two functions: - process_fpemu_return() - cteon_flush_cache_sigtramp() This patch is completely *untested*. Signed-off-by: Davidlohr Bueso Cc: Ralf Baechle Cc: linux-mips@linux-mips.org --- arch/mips/kernel/traps.c | 2 ++ arch/mips/mm/c-octeon.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index 074e857..c51bd20 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -712,10 +712,12 @@ int process_fpemu_return(int sig, void __user *fault_addr) si.si_addr = fault_addr; si.si_signo = sig; if (sig == SIGSEGV) { + down_read(¤t->mm->mmap_sem); if (find_vma(current->mm, (unsigned long)fault_addr)) si.si_code = SEGV_ACCERR; else si.si_code = SEGV_MAPERR; + up_read(¤t->mm->mmap_sem); } else { si.si_code = BUS_ADRERR; } diff --git a/arch/mips/mm/c-octeon.c b/arch/mips/mm/c-octeon.c index f41a5c5..05b1d7c 100644 --- a/arch/mips/mm/c-octeon.c +++ b/arch/mips/mm/c-octeon.c @@ -137,8 +137,10 @@ static void octeon_flush_cache_sigtramp(unsigned long addr) { struct vm_area_struct *vma; + down_read(¤t->mm->mmap_sem); vma = find_vma(current->mm, addr); octeon_flush_icache_all_cores(vma); + up_read(¤t->mm->mmap_sem); } -- 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/