From patchwork Thu Apr 18 09:16:40 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 237546 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 1A3E52C00A7 for ; Thu, 18 Apr 2013 19:18:33 +1000 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1USkz2-0003q9-Ee; Thu, 18 Apr 2013 09:18:24 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1USkyx-0003fe-7Y for kernel-team@lists.ubuntu.com; Thu, 18 Apr 2013 09:18:19 +0000 Received: from bl20-140-10.dsl.telepac.pt ([2.81.140.10] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1USkyw-0002FG-Bn; Thu, 18 Apr 2013 09:18:18 +0000 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 55/72] x86, mm, paravirt: Fix vmalloc_fault oops during lazy MMU updates Date: Thu, 18 Apr 2013 10:16:40 +0100 Message-Id: <1366276617-3553-56-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1366276617-3553-1-git-send-email-luis.henriques@canonical.com> References: <1366276617-3553-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 Cc: "H. Peter Anvin" , Konrad Rzeszutek Wilk , Samu Kallio X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.5.7.11 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Samu Kallio commit 1160c2779b826c6f5c08e5cc542de58fd1f667d5 upstream. In paravirtualized x86_64 kernels, vmalloc_fault may cause an oops when lazy MMU updates are enabled, because set_pgd effects are being deferred. One instance of this problem is during process mm cleanup with memory cgroups enabled. The chain of events is as follows: - zap_pte_range enables lazy MMU updates - zap_pte_range eventually calls mem_cgroup_charge_statistics, which accesses the vmalloc'd mem_cgroup per-cpu stat area - vmalloc_fault is triggered which tries to sync the corresponding PGD entry with set_pgd, but the update is deferred - vmalloc_fault oopses due to a mismatch in the PUD entries The OOPs usually looks as so: ------------[ cut here ]------------ kernel BUG at arch/x86/mm/fault.c:396! invalid opcode: 0000 [#1] SMP .. snip .. CPU 1 Pid: 10866, comm: httpd Not tainted 3.6.10-4.fc18.x86_64 #1 RIP: e030:[] [] vmalloc_fault+0x11f/0x208 .. snip .. Call Trace: [] do_page_fault+0x399/0x4b0 [] ? xen_mc_extend_args+0xec/0x110 [] page_fault+0x25/0x30 [] ? mem_cgroup_charge_statistics.isra.13+0x13/0x50 [] __mem_cgroup_uncharge_common+0xd8/0x350 [] mem_cgroup_uncharge_page+0x57/0x60 [] page_remove_rmap+0xe0/0x150 [] ? vm_normal_page+0x1a/0x80 [] unmap_single_vma+0x531/0x870 [] unmap_vmas+0x52/0xa0 [] ? pte_mfn_to_pfn+0x72/0x100 [] exit_mmap+0x98/0x170 [] ? __raw_callee_save_xen_pmd_val+0x11/0x1e [] mmput+0x83/0xf0 [] exit_mm+0x104/0x130 [] do_exit+0x15a/0x8c0 [] do_group_exit+0x3f/0xa0 [] sys_exit_group+0x17/0x20 [] system_call_fastpath+0x16/0x1b Calling arch_flush_lazy_mmu_mode immediately after set_pgd makes the changes visible to the consistency checks. RedHat-Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=914737 Tested-by: Josh Boyer Reported-and-Tested-by: Krishna Raman Signed-off-by: Samu Kallio Link: http://lkml.kernel.org/r/1364045796-10720-1-git-send-email-konrad.wilk@oracle.com Tested-by: Konrad Rzeszutek Wilk Signed-off-by: Konrad Rzeszutek Wilk Signed-off-by: H. Peter Anvin Signed-off-by: Luis Henriques --- arch/x86/mm/fault.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index c6b10e2..e1a3691 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -377,10 +377,12 @@ static noinline __kprobes int vmalloc_fault(unsigned long address) if (pgd_none(*pgd_ref)) return -1; - if (pgd_none(*pgd)) + if (pgd_none(*pgd)) { set_pgd(pgd, *pgd_ref); - else + arch_flush_lazy_mmu_mode(); + } else { BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); + } /* * Below here mismatches are bugs because these lower tables