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[34.123.190.156]) by smtp.gmail.com with ESMTPSA id g15-20020a02b70f000000b0042bb13cb80fsm3520216jam.120.2023.09.04.11.08.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 Sep 2023 11:08:09 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org, Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes , "Paul E. McKenney" , Vlastimil Babka Cc: "Joel Fernandes (Google)" , Zhen Lei , rcu@vger.kernel.org, Zqiang , stable@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v3 1/2] mm/vmalloc: Add a safer version of find_vm_area() for debug Date: Mon, 4 Sep 2023 18:08:04 +0000 Message-ID: <20230904180806.1002832-1-joel@joelfernandes.org> X-Mailer: git-send-email 2.42.0.283.g2d96d420d3-goog MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org It is unsafe to dump vmalloc area information when trying to do so from some contexts. Add a safer trylock version of the same function to do a best-effort VMA finding and use it from vmalloc_dump_obj(). [applied test robot feedback on unused function fix.] [applied Uladzislau feedback on locking.] Reported-by: Zhen Lei Cc: Paul E. McKenney Cc: rcu@vger.kernel.org Cc: Zqiang Reviewed-by: Uladzislau Rezki (Sony) Fixes: 98f180837a89 ("mm: Make mem_dump_obj() handle vmalloc() memory") Cc: stable@vger.kernel.org Signed-off-by: Joel Fernandes (Google) Reported-by: Zhen Lei Reviewed-by: Uladzislau Rezki (Sony) Signed-off-by: Joel Fernandes (Google) --- mm/vmalloc.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 93cf99aba335..2c6a0e2ff404 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -4274,14 +4274,32 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms) #ifdef CONFIG_PRINTK bool vmalloc_dump_obj(void *object) { - struct vm_struct *vm; void *objp = (void *)PAGE_ALIGN((unsigned long)object); + const void *caller; + struct vm_struct *vm; + struct vmap_area *va; + unsigned long addr; + unsigned int nr_pages; - vm = find_vm_area(objp); - if (!vm) + if (!spin_trylock(&vmap_area_lock)) + return false; + va = __find_vmap_area((unsigned long)objp, &vmap_area_root); + if (!va) { + spin_unlock(&vmap_area_lock); return false; + } + + vm = va->vm; + if (!vm) { + spin_unlock(&vmap_area_lock); + return false; + } + addr = (unsigned long)vm->addr; + caller = vm->caller; + nr_pages = vm->nr_pages; + spin_unlock(&vmap_area_lock); pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n", - vm->nr_pages, (unsigned long)vm->addr, vm->caller); + nr_pages, addr, caller); return true; } #endif From patchwork Mon Sep 4 18:08:05 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 13374260 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 19959CA0FE3 for ; Mon, 4 Sep 2023 18:08:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353397AbjIDSIP (ORCPT ); Mon, 4 Sep 2023 14:08:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237851AbjIDSIP (ORCPT ); Mon, 4 Sep 2023 14:08:15 -0400 Received: from mail-io1-xd2a.google.com (mail-io1-xd2a.google.com [IPv6:2607:f8b0:4864:20::d2a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F014D132 for ; Mon, 4 Sep 2023 11:08:11 -0700 (PDT) Received: by mail-io1-xd2a.google.com with SMTP id ca18e2360f4ac-7926a450a0aso66108139f.3 for ; Mon, 04 Sep 2023 11:08:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; t=1693850891; x=1694455691; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=0tEFwq12UF5zCmmOpDsVAwQyIeVifd7dDTHpnacK0UQ=; b=PTcBrWDTKRVwDJCh5irhuLEFhYUxsCnlwhsHqwYC9Sp0jahhxdX6GwDHbmTDHsvkSz 8U3jcti9oj7DdR42hKGOba0N9st/4c7q5TihNvTLd9BO7OTUdpc0X0dPcdNJ+tUusclR MvMPCECcle8HeKPBRT9GibPeVCwbLkQTGWmv4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693850891; x=1694455691; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=0tEFwq12UF5zCmmOpDsVAwQyIeVifd7dDTHpnacK0UQ=; b=fqJ8LDPdX45eTmQ1wrBH0h+BUF7yvHghl85/o1k72R8kY+HRNcnqjTgMTTC/N+7fhq hUkrq8j6C8Yz1uD948ZF4dk9eiO4ZZue3DCebI9rO+bfrGXGmthjAqf6AYNrcZr1alET xsv6VeloCMLkLiNUqv1BhSPaM3aOm2S4QxMw4MvtgKODv9M2r7YcxmKErq9bFPzm/msx 6+0EmJHgJUIyriwiUmN41Tlj+OGtz/5Mw672DwZCNyNt+X/2EjBenXzItl0fdPTgi9uR kmXQpHbhLemFPZ1PjvEa52WKikmqo4P/8LpNmy+rPnz+fucBEpVeHii6ODEm68iv/k62 4QoQ== X-Gm-Message-State: AOJu0YzYxAE6N2ndf/iDNtU1Pha+UBGWuZ+VBrtyYYU22I2NIfeW+iKv TxX0mnhNEkXM0O1TEjEEIw8s43zc4CvPt7qVCKQ= X-Google-Smtp-Source: AGHT+IEHZt1WRuZqA2Wmfc55FNOuRsD84phTBzjghuiQXLfZnRv1pVitPty4syUUp7DZ6Ov+pU33MA== X-Received: by 2002:a5e:a618:0:b0:794:c9a2:5fe3 with SMTP id q24-20020a5ea618000000b00794c9a25fe3mr12586673ioi.4.1693850891310; Mon, 04 Sep 2023 11:08:11 -0700 (PDT) Received: from joelboxx5.corp.google.com (156.190.123.34.bc.googleusercontent.com. [34.123.190.156]) by smtp.gmail.com with ESMTPSA id g15-20020a02b70f000000b0042bb13cb80fsm3520216jam.120.2023.09.04.11.08.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 Sep 2023 11:08:10 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org, Andrew Morton , "Paul E. McKenney" , Vlastimil Babka Cc: Zqiang , Zhen Lei , rcu@vger.kernel.org, Matthew Wilcox , stable@vger.kernel.org, Joel Fernandes , linux-mm@kvack.org Subject: [PATCH v3 2/2] rcu: Dump vmalloc memory info safely Date: Mon, 4 Sep 2023 18:08:05 +0000 Message-ID: <20230904180806.1002832-2-joel@joelfernandes.org> X-Mailer: git-send-email 2.42.0.283.g2d96d420d3-goog In-Reply-To: <20230904180806.1002832-1-joel@joelfernandes.org> References: <20230904180806.1002832-1-joel@joelfernandes.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org From: Zqiang Currently, for double invoke call_rcu(), will dump rcu_head objects memory info, if the objects is not allocated from the slab allocator, the vmalloc_dump_obj() will be invoke and the vmap_area_lock spinlock need to be held, since the call_rcu() can be invoked in interrupt context, therefore, there is a possibility of spinlock deadlock scenarios. And in Preempt-RT kernel, the rcutorture test also trigger the following lockdep warning: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 1, name: swapper/0 preempt_count: 1, expected: 0 RCU nest depth: 1, expected: 1 3 locks held by swapper/0/1: #0: ffffffffb534ee80 (fullstop_mutex){+.+.}-{4:4}, at: torture_init_begin+0x24/0xa0 #1: ffffffffb5307940 (rcu_read_lock){....}-{1:3}, at: rcu_torture_init+0x1ec7/0x2370 #2: ffffffffb536af40 (vmap_area_lock){+.+.}-{3:3}, at: find_vmap_area+0x1f/0x70 irq event stamp: 565512 hardirqs last enabled at (565511): [] __call_rcu_common+0x218/0x940 hardirqs last disabled at (565512): [] rcu_torture_init+0x20b2/0x2370 softirqs last enabled at (399112): [] __local_bh_enable_ip+0x126/0x170 softirqs last disabled at (399106): [] inet_register_protosw+0x9/0x1d0 Preemption disabled at: [] rcu_torture_init+0x1f13/0x2370 CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 6.5.0-rc4-rt2-yocto-preempt-rt+ #15 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack_lvl+0x68/0xb0 dump_stack+0x14/0x20 __might_resched+0x1aa/0x280 ? __pfx_rcu_torture_err_cb+0x10/0x10 rt_spin_lock+0x53/0x130 ? find_vmap_area+0x1f/0x70 find_vmap_area+0x1f/0x70 vmalloc_dump_obj+0x20/0x60 mem_dump_obj+0x22/0x90 __call_rcu_common+0x5bf/0x940 ? debug_smp_processor_id+0x1b/0x30 call_rcu_hurry+0x14/0x20 rcu_torture_init+0x1f82/0x2370 ? __pfx_rcu_torture_leak_cb+0x10/0x10 ? __pfx_rcu_torture_leak_cb+0x10/0x10 ? __pfx_rcu_torture_init+0x10/0x10 do_one_initcall+0x6c/0x300 ? debug_smp_processor_id+0x1b/0x30 kernel_init_freeable+0x2b9/0x540 ? __pfx_kernel_init+0x10/0x10 kernel_init+0x1f/0x150 ret_from_fork+0x40/0x50 ? __pfx_kernel_init+0x10/0x10 ret_from_fork_asm+0x1b/0x30 The previous patch fixes this by using the deadlock-safe best-effort version of find_vm_area. However, in case of failure print the fact that the pointer was a vmalloc pointer so that we print at least something. Reported-by: Zhen Lei Cc: Paul E. McKenney Cc: rcu@vger.kernel.org Reviewed-by: Matthew Wilcox (Oracle) Fixes: 98f180837a89 ("mm: Make mem_dump_obj() handle vmalloc() memory") Cc: stable@vger.kernel.org Signed-off-by: Zqiang Signed-off-by: Joel Fernandes (Google) --- mm/util.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/util.c b/mm/util.c index dd12b9531ac4..406634f26918 100644 --- a/mm/util.c +++ b/mm/util.c @@ -1071,7 +1071,9 @@ void mem_dump_obj(void *object) if (vmalloc_dump_obj(object)) return; - if (virt_addr_valid(object)) + if (is_vmalloc_addr(object)) + type = "vmalloc memory"; + else if (virt_addr_valid(object)) type = "non-slab/vmalloc memory"; else if (object == NULL) type = "NULL pointer";