From mboxrd@z Thu Jan 1 00:00:00 1970 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 1C1A4C83F37 for ; Thu, 31 Aug 2023 17:18:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346885AbjHaRSn (ORCPT ); Thu, 31 Aug 2023 13:18:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60180 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346723AbjHaRSi (ORCPT ); Thu, 31 Aug 2023 13:18:38 -0400 Received: from mail-io1-xd30.google.com (mail-io1-xd30.google.com [IPv6:2607:f8b0:4864:20::d30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6574ED1 for ; Thu, 31 Aug 2023 10:18:34 -0700 (PDT) Received: by mail-io1-xd30.google.com with SMTP id ca18e2360f4ac-7928ba24936so39680439f.0 for ; Thu, 31 Aug 2023 10:18:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; t=1693502313; x=1694107113; 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=j/9/PG9jMlcZB3crQaMzRcArzBV6KYUSerMEBj6hrg8=; b=wnXucAJkc2nuHeATCDpeHVx9G1R69YpGFcXqhsDDMu5Di7FZMIEzmSpOH1kXZOPdBi WDuXkyGZqQuUTChlJsr7VZXnXl3LTWt57hw9d+HkXQfbEIvnURNj/cDO6otoy+oiKHV0 KEODxwkdQWMDeIk2bsG9rHmKAyvgfSLdLndro= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693502313; x=1694107113; 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=j/9/PG9jMlcZB3crQaMzRcArzBV6KYUSerMEBj6hrg8=; b=IaN3JB1YDF0aljV3quzLZgLNduSRnSGqa2DBVS/l9y4cza/QLDoHsKiu6BHmwmv4VZ RuOdhOZuFzU/eoQveWB4jSoabidwCjmSbqJEcPDOcG4DDQ3d/odIoURv6Yi0No4ntf/V cD7t4gFzX02y0XWRG/V3gjy2RZ/wpl3owozIkYyqRIgXISBpQot+Rvcw22uayDV04c8r 6/pVye8+f1Fix52idYhbRHWPO1geglhzDgMfeWGCdLPysir5hY2tv2Pf1s3vwISGWTWr LiDNoAmMna4nLAk6GrgIz5Bl5Y8CWaC1CGTPVW95GMnANPIQKzXx5N5vcXh6vW/ibPLt JdlA== X-Gm-Message-State: AOJu0YzOYPjoT9C7D4InA5gxY6wN2wwnR0gcNfQ+MO/PPux43Y/60UTZ NXXq0s2Qimv6zAJ3KClCiVWut+RFwDaKc+FphcU= X-Google-Smtp-Source: AGHT+IHcox5PcaIvs7MVFvtB0jCP2GW2W8V6QqMbhxRIywTxp3y1gSk6Bn/EIRCUTsCRwW8btiaIxA== X-Received: by 2002:a05:6602:370a:b0:792:4d29:ecc7 with SMTP id bh10-20020a056602370a00b007924d29ecc7mr6959672iob.15.1693502313379; Thu, 31 Aug 2023 10:18:33 -0700 (PDT) Received: from joelboxx5.c.googlers.com.com (156.190.123.34.bc.googleusercontent.com. [34.123.190.156]) by smtp.gmail.com with ESMTPSA id a16-20020a056638019000b0042af069eeefsm489720jaq.50.2023.08.31.10.18.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 31 Aug 2023 10:18:32 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org, Andrew Morton Cc: Zqiang , Zhen Lei , "Paul E . McKenney" , rcu@vger.kernel.org, Matthew Wilcox , Joel Fernandes , linux-mm@kvack.org Subject: [PATCH v2 2/2] rcu: Dump vmalloc memory info safely Date: Thu, 31 Aug 2023 17:18:26 +0000 Message-ID: <20230831171827.2625016-2-joel@joelfernandes.org> X-Mailer: git-send-email 2.42.0.rc2.253.gd59a3bf2b4-goog In-Reply-To: <20230831171827.2625016-1-joel@joelfernandes.org> References: <20230831171827.2625016-1-joel@joelfernandes.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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) 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"; -- 2.42.0.rc2.253.gd59a3bf2b4-goog