From patchwork Wed Aug 30 11:03:59 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 13370648 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 3F54DC83F1E for ; Wed, 30 Aug 2023 18:48:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243361AbjH3SsD (ORCPT ); Wed, 30 Aug 2023 14:48:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35008 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243455AbjH3LEL (ORCPT ); Wed, 30 Aug 2023 07:04:11 -0400 Received: from mail-il1-x131.google.com (mail-il1-x131.google.com [IPv6:2607:f8b0:4864:20::131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 633D41BF for ; Wed, 30 Aug 2023 04:04:08 -0700 (PDT) Received: by mail-il1-x131.google.com with SMTP id e9e14a558f8ab-34df2a961a0so3588815ab.2 for ; Wed, 30 Aug 2023 04:04:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; t=1693393447; x=1693998247; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=0Bzb0sW6tNrIYQR91p9kftRZaZNiQ/iubHSIhY1eKkc=; b=GJUmWv0U7/GKw3RWPZoxUHg8aeUxd8sBp/DTJ2+rFdnsQZkPQz0ZFyZrSfK54qd2kO RZhkdtBAp9L2FI9cFqNhR/r2GwzxmVnNevg6fF2z79DXg0tPhRKCppiOygJEXQpVKC0R zicpPWZdgIUEA+CmYCxENeVQgtRsoUZMujIDI= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693393447; x=1693998247; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=0Bzb0sW6tNrIYQR91p9kftRZaZNiQ/iubHSIhY1eKkc=; b=SCKLTTMAr/9/wPqKlAYlkMnHCsHXJYfvoZmFOx+OvtC4eJIWj3O1UsTlaPBZCCznHo k3a6glp/0dUQXZKGZltWQhv4uHZbZbd1Ku3aCVV3WLh90uPqrsv4KaDDm5Wm3g6k9Oir vJ0qodGe6YRX505oThzE9q9j/pVDU5450w//CWbPxuqRL8hdDB/J4h30P0Pvffdo7LGk 8+iDZl2KlX+0Qnx2j12Lv20qN50DYVhwodAmHkUTwf0Gz+8eoefuWdQYuicVSYGMKgZq mB8HTNuullTy93UuoVhqcURRikYWl2OQV8EMAPe36yWdB8SqwZjz0uHwKMC2Pys3J4zp XPJw== X-Gm-Message-State: AOJu0YyMXMFVSsfIjhF2QBHaSaDoaFBIRYfGUcbuM1hHE08zpzt0oLDz ar1SpRED7BmNYybnESii36m1Mw== X-Google-Smtp-Source: AGHT+IE0HDgO4IV5KIonhYC6qUiVBNTzmO3mraM6GsxI7117CCavMJf06wCisJIG3/9IfOckEZyYiA== X-Received: by 2002:a05:6e02:f11:b0:346:7c6d:c667 with SMTP id x17-20020a056e020f1100b003467c6dc667mr1886994ilj.13.1693393447713; Wed, 30 Aug 2023 04:04:07 -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 k8-20020a926f08000000b00348880831fdsm3701371ilc.58.2023.08.30.04.04.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Aug 2023 04:04:07 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org, Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes Cc: "Joel Fernandes (Google)" , Zhen Lei , "Paul E . McKenney" , rcu@vger.kernel.org, Zqiang , linux-mm@kvack.org Subject: [PATCH 1/2] mm/vmalloc: Add a safer version of find_vm_area() for debug Date: Wed, 30 Aug 2023 11:03:59 +0000 Message-ID: <20230830110402.386898-1-joel@joelfernandes.org> X-Mailer: git-send-email 2.42.0.rc2.253.gd59a3bf2b4-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(). Reported-by: Zhen Lei Cc: Paul E. McKenney Cc: rcu@vger.kernel.org Cc: Zqiang Signed-off-by: Joel Fernandes (Google) --- mm/vmalloc.c | 35 ++++++++++++++++++++++++++++++++++- 1 file changed, 34 insertions(+), 1 deletion(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 93cf99aba335..dae347e446e6 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1865,6 +1865,18 @@ struct vmap_area *find_vmap_area(unsigned long addr) return va; } +static struct vmap_area *find_vmap_area_trylock(unsigned long addr) +{ + struct vmap_area *va; + + if (!spin_trylock(&vmap_area_lock)) + return NULL; + va = __find_vmap_area(addr, &vmap_area_root); + spin_unlock(&vmap_area_lock); + + return va; +} + static struct vmap_area *find_unlink_vmap_area(unsigned long addr) { struct vmap_area *va; @@ -2671,6 +2683,27 @@ struct vm_struct *find_vm_area(const void *addr) return va->vm; } +/** + * try_to_find_vm_area - find a continuous kernel virtual area + * @addr: base address + * + * This function is the same as find_vm_area() except that it is + * safe to call if vmap_area_lock is already held and returns NULL + * if it is. See comments in find_vmap_area() for other details. + * + * Return: the area descriptor on success or %NULL on failure. + */ +static struct vm_struct *try_to_find_vm_area(const void *addr) +{ + struct vmap_area *va; + + va = find_vmap_area_trylock((unsigned long)addr); + if (!va) + return NULL; + + return va->vm; +} + /** * remove_vm_area - find and remove a continuous kernel virtual area * @addr: base address @@ -4277,7 +4310,7 @@ bool vmalloc_dump_obj(void *object) struct vm_struct *vm; void *objp = (void *)PAGE_ALIGN((unsigned long)object); - vm = find_vm_area(objp); + vm = try_to_find_vm_area(objp); if (!vm) return false; pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n", From patchwork Wed Aug 30 11:04:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 13370649 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 87138C83F26 for ; Wed, 30 Aug 2023 18:48:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243372AbjH3SsF (ORCPT ); Wed, 30 Aug 2023 14:48:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243458AbjH3LEN (ORCPT ); Wed, 30 Aug 2023 07:04:13 -0400 Received: from mail-il1-x134.google.com (mail-il1-x134.google.com [IPv6:2607:f8b0:4864:20::134]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 86044CC9 for ; Wed, 30 Aug 2023 04:04:09 -0700 (PDT) Received: by mail-il1-x134.google.com with SMTP id e9e14a558f8ab-34baf19955cso16782725ab.2 for ; Wed, 30 Aug 2023 04:04:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; t=1693393449; x=1693998249; 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=lHeTYTQd3e1UM6bbclCSBl0XSX253sv8qZjrdw63cyw=; b=XT2OsL8vone9h4Yy4OmsyMpk2y+6JK29K6/bBBRVBW6l9foNBRC97Hf7GgUsraeUyM blWWPincJbqW6PX2S+ZKKqHkAQoI7JQKVJ6hsyNr0z7UiQ7pkJUo/rYh9SLrVQ0gn+uK IH3qBlYF8LASht9S16w2pvBHWs64kKsHyS1s0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693393449; x=1693998249; 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=lHeTYTQd3e1UM6bbclCSBl0XSX253sv8qZjrdw63cyw=; b=evyaxaejWzjnrDi1zuyZNCshO65MwZC4gNWvEfHnqDVgjvDifTlCHlpQ1ehwMj+b5+ 7JwaOqqMitHkKhGEDLKAPnPMKORNjs5yU7eQxJKTjJkZa2NRqlvG4DAzwgnFoYNWOaM9 cg4JwwlmbSgB1fCrh7SX3C5BvebvhalGtVfMdMBqt5Xz8SLAA0fMATclZfz3QMFy218T /QfocxZzu9yQwkDfymZW1lDB4Cd74IdBEvQgjxr0JNdvU6o9cDkVvXdmkyYHJGnCHDIf VSO6lGugcfg3a41pfYcSaIxoTD9wGKsxSntc2UvoEKk1ojuhyd9PZnFbZ2kvbr44kAYn dy6Q== X-Gm-Message-State: AOJu0YxUcNn9E0ISQlyyDTqNL7YzYy0jk/jmLa15TdtYmsUQtRK6+Ylc 91on1k9J5FAS/nm+TlCFNj7B5A== X-Google-Smtp-Source: AGHT+IFund/NrHtbXmr+nM6CwUfYexlETTDEs47RWR1PjvxqSHb7wpadyvNQl1N8KUpp7GybkOZn3Q== X-Received: by 2002:a05:6e02:ee7:b0:34c:b992:58b1 with SMTP id j7-20020a056e020ee700b0034cb99258b1mr1918104ilk.2.1693393448834; Wed, 30 Aug 2023 04:04:08 -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 k8-20020a926f08000000b00348880831fdsm3701371ilc.58.2023.08.30.04.04.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Aug 2023 04:04:08 -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, Joel Fernandes , linux-mm@kvack.org Subject: [PATCH 2/2] rcu: Dump vmalloc memory info safely Date: Wed, 30 Aug 2023 11:04:00 +0000 Message-ID: <20230830110402.386898-2-joel@joelfernandes.org> X-Mailer: git-send-email 2.42.0.rc2.253.gd59a3bf2b4-goog In-Reply-To: <20230830110402.386898-1-joel@joelfernandes.org> References: <20230830110402.386898-1-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 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";