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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org From: Martin Wilck We have observed a few crashes run_timer_softirq(), where a broken timer_list struct belonging to an anatt_timer was encountered. The broken structures look like this, and we see actually multiple ones attached to the same timer base: crash> struct timer_list 0xffff92471bcfdc90 struct timer_list { entry = { next = 0xdead000000000122, // LIST_POISON2 pprev = 0x0 }, expires = 4296022933, function = 0xffffffffc06de5e0 , flags = 20 } If such a timer is encountered in run_timer_softirq(), the kernel crashes. The test scenario was an I/O load test with lots of NVMe controllers, some of which were removed and re-added on the storage side. I think this may happen if the rdma recovery_work starts, in this call chain: nvme_rdma_error_recovery_work() /* this stops all sorts of activity for the controller, but not the multipath-related work queue and timer */ nvme_rdma_reconnect_or_remove(ctrl) => kicks reconnect_work work queue: reconnect_work nvme_rdma_reconnect_ctrl_work() nvme_rdma_setup_ctrl() nvme_rdma_configure_admin_queue() nvme_init_identify() nvme_mpath_init() # this sets some fields of the timer_list without taking a lock timer_setup() nvme_read_ana_log() mod_timer() or del_timer_sync() Similar for TCP. The idea for the patch is based on the observation that nvme_rdma_reset_ctrl_work() calls nvme_stop_ctrl()->nvme_mpath_stop(), whereas nvme_rdma_error_recovery_work() stops only the keepalive timer, but not the anatt timer. Also, nvme_mpath_init() is the only place where the anatt_timer structure is accessed without locking. [The following paragraph was contributed by Chao Leng ] The process maybe:1.ana_work add the timer;2.error recovery occurs, in reconnecting, reinitialize the timer and call nvme_read_ana_log, nvme_read_ana_log may add the timer again. The same timer is added twice, crash will happens later. This situation has actually been observed in a crash dump, where we found an anatt timer pending that had been started ~80s ago, despite a log message telling that the anatt timer for the same controller had timed out a few seconds ago. This could only be explained by the same timer having been attached multiple times. Signed-off-by: Martin Wilck Reviewed-by: Sagi Grimberg Reviewed-by: Chao Leng Cc: stable@vger.kernel.org ---- Changes in v4: Updated commit message with Chao Leng's analysis, as suggested by Daniel Wagner. Changes in v3: Changed the subject line, as suggested by Sagi Grimberg Changes in v2: Moved call to nvme_mpath_stop() further down, directly before the call of nvme_rdma_reconnect_or_remove() (Chao Leng) --- drivers/nvme/host/multipath.c | 1 + drivers/nvme/host/rdma.c | 1 + drivers/nvme/host/tcp.c | 1 + 3 files changed, 3 insertions(+) diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c index a1d476e1ac02..c63dd5dfa7ff 100644 --- a/drivers/nvme/host/multipath.c +++ b/drivers/nvme/host/multipath.c @@ -586,6 +586,7 @@ void nvme_mpath_stop(struct nvme_ctrl *ctrl) del_timer_sync(&ctrl->anatt_timer); cancel_work_sync(&ctrl->ana_work); } +EXPORT_SYMBOL_GPL(nvme_mpath_stop); #define SUBSYS_ATTR_RW(_name, _mode, _show, _store) \ struct device_attribute subsys_attr_##_name = \ diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c index be905d4fdb47..fc07a7b0dc1d 100644 --- a/drivers/nvme/host/rdma.c +++ b/drivers/nvme/host/rdma.c @@ -1202,6 +1202,7 @@ static void nvme_rdma_error_recovery_work(struct work_struct *work) return; } + nvme_mpath_stop(&ctrl->ctrl); nvme_rdma_reconnect_or_remove(ctrl); } diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c index a0f00cb8f9f3..46287b4f4d10 100644 --- a/drivers/nvme/host/tcp.c +++ b/drivers/nvme/host/tcp.c @@ -2068,6 +2068,7 @@ static void nvme_tcp_error_recovery_work(struct work_struct *work) return; } + nvme_mpath_stop(ctrl); nvme_tcp_reconnect_or_remove(ctrl); } -- 2.31.1 _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme 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 X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 66D1AC433ED for ; Tue, 27 Apr 2021 09:31:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 236E6613BC for ; Tue, 27 Apr 2021 09:31:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235033AbhD0Jc1 (ORCPT ); Tue, 27 Apr 2021 05:32:27 -0400 Received: from mx2.suse.de ([195.135.220.15]:42554 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230316AbhD0Jc1 (ORCPT ); Tue, 27 Apr 2021 05:32:27 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1619515903; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=dq8xvoiQYVgM3UOKENRARpfRaj5alyyZsdLug8PnLwM=; b=MueakfsLqRY/FwzbUVHI9oJIGEJkbTILkwBiKfvtB7ha2Es+t4afybOJ8+P6FFbtilTmyR iaKFVE3p8LgYH+fOXoUPxVMR8nSWrO6xKnplnQy0jY4iDYCkymWAWI9uvaOCEJbccpEadU feVD7shGcn+xUjrOmn4bCFCY6wlpGvU= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 25F89B124; Tue, 27 Apr 2021 09:31:43 +0000 (UTC) From: mwilck@suse.com To: Keith Busch , Sagi Grimberg , Christoph Hellwig , Chao Leng Cc: Hannes Reinecke , Daniel Wagner , linux-nvme@lists.infradead.org, Martin Wilck , stable@vger.kernel.org Subject: [PATCH v4] nvme: rdma/tcp: fix list corruption with anatt timer Date: Tue, 27 Apr 2021 11:31:10 +0200 Message-Id: <20210427093110.16461-1-mwilck@suse.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Martin Wilck We have observed a few crashes run_timer_softirq(), where a broken timer_list struct belonging to an anatt_timer was encountered. The broken structures look like this, and we see actually multiple ones attached to the same timer base: crash> struct timer_list 0xffff92471bcfdc90 struct timer_list { entry = { next = 0xdead000000000122, // LIST_POISON2 pprev = 0x0 }, expires = 4296022933, function = 0xffffffffc06de5e0 , flags = 20 } If such a timer is encountered in run_timer_softirq(), the kernel crashes. The test scenario was an I/O load test with lots of NVMe controllers, some of which were removed and re-added on the storage side. I think this may happen if the rdma recovery_work starts, in this call chain: nvme_rdma_error_recovery_work() /* this stops all sorts of activity for the controller, but not the multipath-related work queue and timer */ nvme_rdma_reconnect_or_remove(ctrl) => kicks reconnect_work work queue: reconnect_work nvme_rdma_reconnect_ctrl_work() nvme_rdma_setup_ctrl() nvme_rdma_configure_admin_queue() nvme_init_identify() nvme_mpath_init() # this sets some fields of the timer_list without taking a lock timer_setup() nvme_read_ana_log() mod_timer() or del_timer_sync() Similar for TCP. The idea for the patch is based on the observation that nvme_rdma_reset_ctrl_work() calls nvme_stop_ctrl()->nvme_mpath_stop(), whereas nvme_rdma_error_recovery_work() stops only the keepalive timer, but not the anatt timer. Also, nvme_mpath_init() is the only place where the anatt_timer structure is accessed without locking. [The following paragraph was contributed by Chao Leng ] The process maybe:1.ana_work add the timer;2.error recovery occurs, in reconnecting, reinitialize the timer and call nvme_read_ana_log, nvme_read_ana_log may add the timer again. The same timer is added twice, crash will happens later. This situation has actually been observed in a crash dump, where we found an anatt timer pending that had been started ~80s ago, despite a log message telling that the anatt timer for the same controller had timed out a few seconds ago. This could only be explained by the same timer having been attached multiple times. Signed-off-by: Martin Wilck Reviewed-by: Sagi Grimberg Reviewed-by: Chao Leng Cc: stable@vger.kernel.org ---- Changes in v4: Updated commit message with Chao Leng's analysis, as suggested by Daniel Wagner. Changes in v3: Changed the subject line, as suggested by Sagi Grimberg Changes in v2: Moved call to nvme_mpath_stop() further down, directly before the call of nvme_rdma_reconnect_or_remove() (Chao Leng) --- drivers/nvme/host/multipath.c | 1 + drivers/nvme/host/rdma.c | 1 + drivers/nvme/host/tcp.c | 1 + 3 files changed, 3 insertions(+) diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c index a1d476e1ac02..c63dd5dfa7ff 100644 --- a/drivers/nvme/host/multipath.c +++ b/drivers/nvme/host/multipath.c @@ -586,6 +586,7 @@ void nvme_mpath_stop(struct nvme_ctrl *ctrl) del_timer_sync(&ctrl->anatt_timer); cancel_work_sync(&ctrl->ana_work); } +EXPORT_SYMBOL_GPL(nvme_mpath_stop); #define SUBSYS_ATTR_RW(_name, _mode, _show, _store) \ struct device_attribute subsys_attr_##_name = \ diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c index be905d4fdb47..fc07a7b0dc1d 100644 --- a/drivers/nvme/host/rdma.c +++ b/drivers/nvme/host/rdma.c @@ -1202,6 +1202,7 @@ static void nvme_rdma_error_recovery_work(struct work_struct *work) return; } + nvme_mpath_stop(&ctrl->ctrl); nvme_rdma_reconnect_or_remove(ctrl); } diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c index a0f00cb8f9f3..46287b4f4d10 100644 --- a/drivers/nvme/host/tcp.c +++ b/drivers/nvme/host/tcp.c @@ -2068,6 +2068,7 @@ static void nvme_tcp_error_recovery_work(struct work_struct *work) return; } + nvme_mpath_stop(ctrl); nvme_tcp_reconnect_or_remove(ctrl); } -- 2.31.1