From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f69.google.com (mail-pl0-f69.google.com [209.85.160.69]) by kanga.kvack.org (Postfix) with ESMTP id 5FEBD6B0008 for ; Mon, 19 Mar 2018 14:13:41 -0400 (EDT) Received: by mail-pl0-f69.google.com with SMTP id f59-v6so11025421plb.7 for ; Mon, 19 Mar 2018 11:13:41 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id l189si347963pfl.47.2018.03.19.11.13.40 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 19 Mar 2018 11:13:40 -0700 (PDT) From: Greg Kroah-Hartman Subject: [PATCH 4.4 036/134] mm: Fix false-positive VM_BUG_ON() in page_cache_{get,add}_speculative() Date: Mon, 19 Mar 2018 19:05:19 +0100 Message-Id: <20180319171854.521145165@linuxfoundation.org> In-Reply-To: <20180319171849.024066323@linuxfoundation.org> References: <20180319171849.024066323@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Fengguang Wu , "Kirill A. Shutemov" , Andrew Morton , "Aneesh Kumar K.V" , "Kirill A. Shutemov" , LKP , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , linux-mm@kvack.org, Ingo Molnar , Sasha Levin 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Kirill A. Shutemov" [ Upstream commit 591a3d7c09fa08baff48ad86c2347dbd28a52753 ] 0day testing by Fengguang Wu triggered this crash while running Trinity: kernel BUG at include/linux/pagemap.h:151! ... CPU: 0 PID: 458 Comm: trinity-c0 Not tainted 4.11.0-rc2-00251-g2947ba0 #1 ... Call Trace: __get_user_pages_fast() get_user_pages_fast() get_futex_key() futex_requeue() do_futex() SyS_futex() do_syscall_64() entry_SYSCALL64_slow_path() It' VM_BUG_ON() due to false-negative in_atomic(). We call page_cache_get_speculative() with disabled local interrupts. It should be atomic enough. So let's check for disabled interrupts in the VM_BUG_ON() condition too, to resolve this. ( This got triggered by the conversion of the x86 GUP code to the generic GUP code. ) Reported-by: Fengguang Wu Signed-off-by: Kirill A. Shutemov Cc: Andrew Morton Cc: Aneesh Kumar K.V Cc: Kirill A. Shutemov Cc: LKP Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20170324114709.pcytvyb3d6ajux33@black.fi.intel.com Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- include/linux/pagemap.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -153,7 +153,7 @@ static inline int page_cache_get_specula #ifdef CONFIG_TINY_RCU # ifdef CONFIG_PREEMPT_COUNT - VM_BUG_ON(!in_atomic()); + VM_BUG_ON(!in_atomic() && !irqs_disabled()); # endif /* * Preempt must be disabled here - we rely on rcu_read_lock doing @@ -191,7 +191,7 @@ static inline int page_cache_add_specula #if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU) # ifdef CONFIG_PREEMPT_COUNT - VM_BUG_ON(!in_atomic()); + VM_BUG_ON(!in_atomic() && !irqs_disabled()); # endif VM_BUG_ON_PAGE(page_count(page) == 0, page); atomic_add(count, &page->_count);