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 7D898C001DF for ; Thu, 3 Aug 2023 10:19:20 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4055D2801EB; Thu, 3 Aug 2023 06:19:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 37DC828022E; Thu, 3 Aug 2023 06:19:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0E0712801EB; Thu, 3 Aug 2023 06:19:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id E78F928022C for ; Thu, 3 Aug 2023 06:19:17 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id AB37EA04F8 for ; Thu, 3 Aug 2023 10:19:17 +0000 (UTC) X-FDA: 81082395954.30.6596ACD Received: from dggsgout11.his.huawei.com (unknown [45.249.212.51]) by imf13.hostedemail.com (Postfix) with ESMTP id 88EAA2000B for ; Thu, 3 Aug 2023 10:19:14 +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=1691057955; 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=njcyC+Y7DyPrI2hfeo2ZY81l5420qr70wW3AZzYp6G8=; b=CwTs4+cy79LY5zRZrGh6jP58E7F5D0ZHUZQ+zyt3dWUiKmQPTd+4ZVOdLqXI6h4hyb+QNZ RJXfEA3iFdnzVTcdV/QNRJhV9JCVeUjDiwPGzq16b9XHfv6SsO/Bj4KRWm886/QR+dp8aY p9EzEXMprEigbO5wFDX+VyGAvsHWBwc= 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=1691057955; a=rsa-sha256; cv=none; b=1THvkdR6JNd+a0pugiHl22Tc12BtdsuSvrdIBZCE8Lrz1ZkgLa7TrtzHkgD3ir8vFTUc8L FNjqG6ljOfN1rWOeI+I9Kfrr3aXS7IfQLGNomHfh983B0FJ0IxwGTmbDnKhPNfXS57uG6z Wbh3ZCiPERS32P3JSuOfxtgVscc6r60= Received: from mail02.huawei.com (unknown [172.30.67.143]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4RGlF73fcnz4f4Vxd for ; Thu, 3 Aug 2023 18:19:07 +0800 (CST) Received: from huaweicloud.com (unknown [10.174.178.55]) by APP4 (Coremail) with SMTP id gCh0CgD3mp4Uf8tk4+TaPQ--.35755S6; Thu, 03 Aug 2023 18:19:08 +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 v5 2/3] rcu: Dump memory object info if callback function is invalid Date: Thu, 3 Aug 2023 18:17:53 +0800 Message-Id: <20230803101754.1149-3-thunder.leizhen@huaweicloud.com> X-Mailer: git-send-email 2.37.3.windows.1 In-Reply-To: <20230803101754.1149-1-thunder.leizhen@huaweicloud.com> References: <20230803101754.1149-1-thunder.leizhen@huaweicloud.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:gCh0CgD3mp4Uf8tk4+TaPQ--.35755S6 X-Coremail-Antispam: 1UD129KBjvJXoWxtF47WrW7Kw1fury3tFWrZrb_yoW7GrW3pr ykuFy7Kw4kXFyrtay7Zw18WrWUA39Ygay3Ka95Crn3Cw4Ykr10gFyqyF12qrWYqF1rK34a qF1YqF43tr40ywUanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPjb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6r1S6rWUM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUXw A2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMc Ij6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_ Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lw4CEc2x0rVAKj4 xxMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_ Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVW8ZVWrXwCIc40Y0x 0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWx JVW8Jr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMI IF0xvEx4A2jsIEc7CjxVAFwI0_Gr1j6F4UJbIYCTnIWIevJa73UjIFyTuYvjxUwzuAUUUU U X-CM-SenderInfo: hwkx0vthuozvpl2kv046kxt4xhlfz01xgou0bp/ X-CFilter-Loop: Reflected X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 88EAA2000B X-Stat-Signature: 1eoq1kgi4nr33o5ni6smbm1x5stjyakm X-HE-Tag: 1691057954-117691 X-HE-Meta: U2FsdGVkX1+pXiYhVw583928tN4EWfHBISI05cTsjrNCbDqdXPkW8XoSfR73+O/u/m7paGH2zhHInk/afu+lnUO82cHN00oadM9sXM9RlyHT/82i75vWele2srZ81oDoX1KENUfB5OeiOPlms+849BelbLR2MKK0dIq6Of20bngFB5vDdrdhOFKdIKWPSkx0j0Dm0I/ChU4PWz2ekhV1XD1mUPJg03Gdbz9lem4IeaQGYMGMhBLrVZ5mP1BZvb67TPdCAqI0z1U58oye5shsgwzGUWUbI/AI9RUpntsDb/X5tabhgcaMh0u+quLWbQUWN7jCwlBdUHvMJKBEBS0i2Z8NoPFjDKCGdp/xtIFdCKCsZSm9MDf88lLJAYKT7mbxDDtCeZ16f0TnVeV6tQRcumCESoiIILj0TFT1WT02+rEvnziuLS0qY25DXcP6glt84Y1GNH/rELpbYUN8DOFHmKFm/662ZALDxXh3wTihDJ5SGXmHI+OO6S1DYJnNh8NqndX3A6kpCiL7FSdXmNt1T0BmGEK3/HdvoPycRMD0CtNxAWG9uJXxLtaYVT8DDMyvS95mSxYDv1PsYaqrhN8/5A9wnUg+GW4gB53jBhX1ybSrCqKMcBfCUFOtvH3bGhtjRD/YaqFRnBXLDP9861S47Qux9O0ouJViN4dFte7Jy+UByfhksyuOszPBBc4BeL8gGMnDMF5LD8NQuG6Tvbzb8W1sXzH7uUpa13g7biWiXtitX6y2hVXTQ3E8YU5gXY29hw+wstownSQr19YyRa0hDnGY8WPaBSIHIvxkXb8FFLkWg2gXaKJVupOnPrW+0RIRn+ogPf//PkvWcbsNlkFYOVkdyUB7t/sR24KeIUZr2OMbJPtLZHHhkwlF8GuEwvjLzVv4ZS/oVfH0rAwcnnTqo30uQ9+M+P8XMWfAup874/HKChSjHXgfcVA4pwkFPKATPdGhYzfagvZHktTvTP4 czu+H2h2 2z4MBAUd4mBZ2sjHhmEqZDvN9NE1eOiFwgnUvQCos6SnX9t46y0zBb46OThBQORRocGE1j//VRh3NfCJ0FJaX5DIP6osQc+3v9hKnQkNfd7gxc95j6Kr0t0zdpqsVgHUwNwwNR3YSR+HT75dYdDA3CyDez2EqhoLvIUCFdfu7twFJipYFfBv6WCnotRJB6VENlHMpjbmPWCKlf3SSh2janABQnyuE7xEVR/KvMI1/9dUvV3KUv13D4eE8sQ82SbPWriErVl9pLwAeVN3Vc3Nhhl98RA0lrycT4H6HVKQTAR1vPepQa7sq4spPxg== 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 7294be62727b12c..148ac6a464bfb12 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -538,6 +538,7 @@ 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 7c79480bfaa04e4..927c5ba0ae42269 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