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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED60AC00528 for ; Sat, 5 Aug 2023 03:21:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5CFB98D0005; Fri, 4 Aug 2023 23:21:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5587F8D0001; Fri, 4 Aug 2023 23:21:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 35CC38D0006; Fri, 4 Aug 2023 23:21:04 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 24A628D0005 for ; Fri, 4 Aug 2023 23:21:04 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id E4C50406AA for ; Sat, 5 Aug 2023 03:21:03 +0000 (UTC) X-FDA: 81088599606.17.6ED8D7A Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by imf13.hostedemail.com (Postfix) with ESMTP id 57AD12000B for ; Sat, 5 Aug 2023 03:20:59 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=none; dmarc=none; spf=none (imf13.hostedemail.com: domain of thunder.leizhen@huaweicloud.com has no SPF policy when checking 45.249.212.51) smtp.mailfrom=thunder.leizhen@huaweicloud.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1691205661; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=dziUvwZoWZ9u7z52E8xkj1w8ozZk1JRCp9+7XqkjIx8=; b=8HX7AnuinmC/HSNp5ASeuP6LOa4OlMNo5A/6YTy+iUfJYnShTcrEEHa5zN4JJa3JIMVDUa yJMS+3SkPKBFYhVt63K+8UZ2UayYSquivtzlSSO9d2PkhkZ04VYhmXS7CE3c0m4ZiK5Fq1 GOdGII3e82twxwN8jULSrwxyu18UHRg= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=none; dmarc=none; spf=none (imf13.hostedemail.com: domain of thunder.leizhen@huaweicloud.com has no SPF policy when checking 45.249.212.51) smtp.mailfrom=thunder.leizhen@huaweicloud.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1691205661; a=rsa-sha256; cv=none; b=vf96jG+JrnZt404niiF7wNRdg9DVLx+3q8s1sgsBeLsNy5v4dHyJsgXen8gA+r77ujKva1 j6/JLs4o0x6TYC8yltjod+21k+dfDm1JNlz652V3EnJh9+atWudrViZDWOKg+f1CrR11GO V+FXSmUoTapb4Pays40FA0HGJJmmrtY= Received: from mail02.huawei.com (unknown [172.30.67.143]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4RHnsg0N4Dz4f3kpH for ; Sat, 5 Aug 2023 11:20:55 +0800 (CST) Received: from huaweicloud.com (unknown [10.174.178.55]) by APP4 (Coremail) with SMTP id gCh0CgAHoZQRwM1kZdNePg--.61999S6; Sat, 05 Aug 2023 11:20:55 +0800 (CST) From: thunder.leizhen@huaweicloud.com To: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, "Paul E . McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , rcu@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Zhen Lei Subject: [PATCH v7 2/2] rcu: Dump memory object info if callback function is invalid Date: Sat, 5 Aug 2023 11:17:26 +0800 Message-Id: <20230805031726.1230-3-thunder.leizhen@huaweicloud.com> X-Mailer: git-send-email 2.37.3.windows.1 In-Reply-To: <20230805031726.1230-1-thunder.leizhen@huaweicloud.com> References: <20230805031726.1230-1-thunder.leizhen@huaweicloud.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:gCh0CgAHoZQRwM1kZdNePg--.61999S6 X-Coremail-Antispam: 1UD129KBjvJXoWxtF47WrW7Kw1fury3tFWrZrb_yoW7GrW3pr ykury7Kw4kXFyrtay7Zw18WrWUA39Ygay3Ka95Crs3Cw4Ykw10gFyqyF12qrWYqF1rK34a qF1YqF47tw48AwUanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBEb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6r1S6rWUM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUXw A2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMc Ij6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_ Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lw4CEc2x0rVAKj4 xxMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_ Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVW8ZVWrXwCIc40Y0x 0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWx JVW8Jr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMI IF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x07UtR67UUUUU = X-CM-SenderInfo: hwkx0vthuozvpl2kv046kxt4xhlfz01xgou0bp/ X-CFilter-Loop: Reflected X-Rspam-User: X-Stat-Signature: h4e7fu49861sumfe7i1zujs5qw8rhq7h X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 57AD12000B X-HE-Tag: 1691205659-227992 X-HE-Meta: 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 NHeDfwzg tVWpLQZnrQO0d9H6f5EIhF0FvG7vAdHZu7kfVc1gFdYjSHCLZ+yKtUdATv5TtGSsxOTcFWYMDXDfK/HDu0G3n3zsG1VJ6YJNucxYOuK9EEFJe5RId2rGdh34wlRSNedngytUvktrNe9IoicuUral7RB9GwBkOZ5Aeq1/NwDSgUzLGVWF+KbjWPK4sGSPYWt9G/V00lRKcbGU0Va3mvjlIUC+nAAL51HgtjAdV8F22ySO+ARurIecARHpeVvIhzShTHlttKMi5QuO8rosM1bhQPgq+i3hAM0MvnDOOlwmMtf6aHc62FDba4J616QSf5QFap1y/ZZ9stXTkcz60ZkzqS3lJzC9JmwwbBs3Ri7q3quKbQ5U= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Zhen Lei When a structure containing an RCU callback rhp is (incorrectly) freed and reallocated after rhp is passed to call_rcu(), it is not unusual for rhp->func to be set to NULL. This defeats the debugging prints used by __call_rcu_common() in kernels built with CONFIG_DEBUG_OBJECTS_RCU_HEAD=y, which expect to identify the offending code using the identity of this function. And in kernels build without CONFIG_DEBUG_OBJECTS_RCU_HEAD=y, things are even worse, as can be seen from this splat: Unable to handle kernel NULL pointer dereference at virtual address 0 ... ... PC is at 0x0 LR is at rcu_do_batch+0x1c0/0x3b8 ... ... (rcu_do_batch) from (rcu_core+0x1d4/0x284) (rcu_core) from (__do_softirq+0x24c/0x344) (__do_softirq) from (__irq_exit_rcu+0x64/0x108) (__irq_exit_rcu) from (irq_exit+0x8/0x10) (irq_exit) from (__handle_domain_irq+0x74/0x9c) (__handle_domain_irq) from (gic_handle_irq+0x8c/0x98) (gic_handle_irq) from (__irq_svc+0x5c/0x94) (__irq_svc) from (arch_cpu_idle+0x20/0x3c) (arch_cpu_idle) from (default_idle_call+0x4c/0x78) (default_idle_call) from (do_idle+0xf8/0x150) (do_idle) from (cpu_startup_entry+0x18/0x20) (cpu_startup_entry) from (0xc01530) This commit therefore adds calls to mem_dump_obj(rhp) to output some information, for example: slab kmalloc-256 start ffff410c45019900 pointer offset 0 size 256 This provides the rough size of the memory block and the offset of the rcu_head structure, which as least provides at least a few clues to help locate the problem. If the problem is reproducible, additional slab debugging can be enabled, for example, CONFIG_DEBUG_SLAB=y, which can provide significantly more information. Signed-off-by: Zhen Lei --- kernel/rcu/rcu.h | 7 +++++++ kernel/rcu/srcutiny.c | 1 + kernel/rcu/srcutree.c | 1 + kernel/rcu/tasks.h | 1 + kernel/rcu/tiny.c | 1 + kernel/rcu/tree.c | 1 + 6 files changed, 12 insertions(+) diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index d1dcb09750efbd6..bc81582238b9846 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -10,6 +10,7 @@ #ifndef __LINUX_RCU_H #define __LINUX_RCU_H +#include #include /* @@ -248,6 +249,12 @@ static inline void debug_rcu_head_unqueue(struct rcu_head *head) } #endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ +static inline void debug_rcu_head_callback(struct rcu_head *rhp) +{ + if (unlikely(!rhp->func)) + kmem_dump_obj(rhp); +} + extern int rcu_cpu_stall_suppress_at_boot; static inline bool rcu_stall_is_suppressed_at_boot(void) diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c index 336af24e0fe358a..c38e5933a5d6937 100644 --- a/kernel/rcu/srcutiny.c +++ b/kernel/rcu/srcutiny.c @@ -138,6 +138,7 @@ void srcu_drive_gp(struct work_struct *wp) while (lh) { rhp = lh; lh = lh->next; + debug_rcu_head_callback(rhp); local_bh_disable(); rhp->func(rhp); local_bh_enable(); diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index f1a905200fc2f79..833a8f848a90ae6 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1710,6 +1710,7 @@ static void srcu_invoke_callbacks(struct work_struct *work) rhp = rcu_cblist_dequeue(&ready_cbs); for (; rhp != NULL; rhp = rcu_cblist_dequeue(&ready_cbs)) { debug_rcu_head_unqueue(rhp); + debug_rcu_head_callback(rhp); local_bh_disable(); rhp->func(rhp); local_bh_enable(); diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 018f03f20629018..1fa631168594d1b 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -540,6 +540,7 @@ static void rcu_tasks_invoke_cbs(struct rcu_tasks *rtp, struct rcu_tasks_percpu raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags); len = rcl.len; for (rhp = rcu_cblist_dequeue(&rcl); rhp; rhp = rcu_cblist_dequeue(&rcl)) { + debug_rcu_head_callback(rhp); local_bh_disable(); rhp->func(rhp); local_bh_enable(); diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c index 42f7589e51e09e7..fec804b7908032d 100644 --- a/kernel/rcu/tiny.c +++ b/kernel/rcu/tiny.c @@ -97,6 +97,7 @@ static inline bool rcu_reclaim_tiny(struct rcu_head *head) trace_rcu_invoke_callback("", head); f = head->func; + debug_rcu_head_callback(head); WRITE_ONCE(head->func, (rcu_callback_t)0L); f(head); rcu_lock_release(&rcu_callback_map); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 3c7281fc25a795b..aae515071ffd821 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2135,6 +2135,7 @@ static void rcu_do_batch(struct rcu_data *rdp) trace_rcu_invoke_callback(rcu_state.name, rhp); f = rhp->func; + debug_rcu_head_callback(rhp); WRITE_ONCE(rhp->func, (rcu_callback_t)0L); f(rhp); -- 2.34.1