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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 86475C433E0 for ; Fri, 29 Jan 2021 01:24:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 50BBF60C41 for ; Fri, 29 Jan 2021 01:24:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231801AbhA2BY1 (ORCPT ); Thu, 28 Jan 2021 20:24:27 -0500 Received: from szxga01-in.huawei.com ([45.249.212.187]:4594 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231184AbhA2BYP (ORCPT ); Thu, 28 Jan 2021 20:24:15 -0500 Received: from DGGEMM401-HUB.china.huawei.com (unknown [172.30.72.54]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4DRfhf2GvjzY2nX; Fri, 29 Jan 2021 09:22:26 +0800 (CST) Received: from dggema772-chm.china.huawei.com (10.1.198.214) by DGGEMM401-HUB.china.huawei.com (10.3.20.209) with Microsoft SMTP Server (TLS) id 14.3.498.0; Fri, 29 Jan 2021 09:23:32 +0800 Received: from [10.169.42.93] (10.169.42.93) by dggema772-chm.china.huawei.com (10.1.198.214) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2106.2; Fri, 29 Jan 2021 09:23:32 +0800 Subject: Re: [PATCH v2] nvme-multipath: Early exit if no path is available To: Daniel Wagner CC: , Sagi Grimberg , , Jens Axboe , Hannes Reinecke , Keith Busch , Christoph Hellwig References: <20210127103033.15318-1-dwagner@suse.de> <20210128075837.u5u56t23fq5gu6ou@beryllium.lan> <69575290-200e-b4a1-4269-c71e4c2cc37b@huawei.com> <20210128094004.erwnszjqcxlsi2kd@beryllium.lan> From: Chao Leng Message-ID: Date: Fri, 29 Jan 2021 09:23:31 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20210128094004.erwnszjqcxlsi2kd@beryllium.lan> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.169.42.93] X-ClientProxiedBy: dggeme708-chm.china.huawei.com (10.1.199.104) To dggema772-chm.china.huawei.com (10.1.198.214) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/1/28 17:40, Daniel Wagner wrote: > On Thu, Jan 28, 2021 at 05:18:56PM +0800, Chao Leng wrote: >> It is impossible to return NULL for nvme_next_ns(head, old). > > block nvme0n1: no usable path - requeuing I/O > block nvme0n1: no usable path - requeuing I/O > block nvme0n1: no usable path - requeuing I/O > block nvme0n1: no usable path - requeuing I/O > block nvme0n1: no usable path - requeuing I/O > block nvme0n1: no usable path - requeuing I/O > BUG: kernel NULL pointer dereference, address: 0000000000000068 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 8000000ff67bc067 P4D 8000000ff67bc067 PUD ff9ac9067 PMD 0 > Oops: 0000 [#1] SMP PTI > CPU: 23 PID: 15759 Comm: dt.21.15 Kdump: loaded Tainted: G E 5.3.18-0.gc9fe679-default #1 SLE15-SP2 (unreleased) > Hardware name: FUJITSU PRIMERGY RX2540 M2/D3289-B1, BIOS V5.0.0.11 R1.18.0 for D3289-B1x 02/06/2018 > RIP: 0010:nvme_ns_head_make_request+0x1d1/0x430 [nvme_core] > Code: 54 24 10 0f 84 c9 01 00 00 48 8b 54 24 10 48 83 ea 30 0f 84 ba 01 00 00 48 39 d0 0f 84 01 02 00 00 31 ff eb 05 48 39 d0 74 67 <48> 8b 72 68 83 e6 04 75 13 48 8b 72 68 83 e6 01 75 0a 48 8b 72 10 > RSP: 0018:ffffa69d08017af8 EFLAGS: 00010246 > RAX: ffff92f261d87800 RBX: ffff92fa555b0010 RCX: ffff92fa555bc570 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > RBP: 0000000000000001 R08: 0000000000001000 R09: 0000000000001000 > R10: ffffa69d080179a8 R11: ffff92f264f0c1c0 R12: ffff92f264f7f000 > R13: ffff92fa555b0000 R14: 0000000000000001 R15: 0000000000000000 > FS: 00007f3962bae700(0000) GS:ffff92f29ffc0000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000068 CR3: 0000000fd69a2002 CR4: 00000000003606e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > generic_make_request+0x121/0x300 > ? submit_bio+0x42/0x1c0 > submit_bio+0x42/0x1c0 > ext4_io_submit+0x49/0x60 [ext4] > ext4_writepages+0x625/0xe90 [ext4] > ? do_writepages+0x4b/0xe0 > ? ext4_mark_inode_dirty+0x1d0/0x1d0 [ext4] > do_writepages+0x4b/0xe0 > ? __generic_file_write_iter+0x192/0x1c0 > ? __filemap_fdatawrite_range+0xcb/0x100 > __filemap_fdatawrite_range+0xcb/0x100 > ? ext4_file_write_iter+0x128/0x3c0 [ext4] > file_write_and_wait_range+0x5e/0xb0 > __generic_file_fsync+0x22/0xb0 > ext4_sync_file+0x1f7/0x3c0 [ext4] > do_fsync+0x38/0x60 > __x64_sys_fsync+0x10/0x20 > do_syscall_64+0x5b/0x1e0 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > You can't see exactly where it dies but I followed the assembly to > nvme_round_robin_path(). Maybe it's not the initial nvme_next_ns(head, > old) which returns NULL but nvme_next_ns() is returning NULL eventually > (list_next_or_null_rcu()). So there is other bug cause nvme_next_ns abormal. I review the code about head->list and head->current_path, I find 2 bugs may cause the bug: First, I already send the patch. see: https://lore.kernel.org/linux-nvme/20210128033351.22116-1-lengchao@huawei.com/ Second, in nvme_ns_remove, list_del_rcu is before nvme_mpath_clear_current_path. This may cause "old" is deleted from the "head", but still use "old". I'm not sure there's any other consideration here, I will check it and try to fix it. > > And I have positive feedback, this patch fixes the above problem. Although adding check ns can fix the crash. There may still be other problems such as in __nvme_find_path which use list_for_each_entry_rcu. > > . > 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=-5.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 BCA6EC433DB for ; Fri, 29 Jan 2021 01:23:48 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0525860C41 for ; Fri, 29 Jan 2021 01:23:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0525860C41 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=q9gBtYXoIG61LJGl5bG9zjBNihbQe7XhMANRTvYrvLo=; b=BPOy14qt7cIB9AuzYTbDhZnXY GN1kUPhgfJxA44LC2znUdh2YXjrs+8DP98ovMsbnXgggveFtiMaCcE/avYpE8AEhULHYvEktqDCSd DOxzHeyN5D59dQdTkK38Q03KfIR1mE79jOy1M4hUx2JVMR0HFYwSvZNegtlwpxXrLWvZAqZmvtcIh 5YiqAA8ZRapx06v1L9+fxnf+1R2IQ/9iN7MDcZWDtT0xE8WBXYh7ggxK0vkeSzhSQ52sX22sQasWu X8/g3mP8+v679gIFeVl+NU3vcbpolGoKu/RJ07Kwn00yFAczDVWU1PsmiCyFdpXkARgYavm05N14v +uYev7qLg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l5IVh-0000HC-8j; Fri, 29 Jan 2021 01:23:41 +0000 Received: from szxga01-in.huawei.com ([45.249.212.187]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l5IVd-0000Ga-Nk for linux-nvme@lists.infradead.org; Fri, 29 Jan 2021 01:23:39 +0000 Received: from DGGEMM401-HUB.china.huawei.com (unknown [172.30.72.54]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4DRfhf2GvjzY2nX; Fri, 29 Jan 2021 09:22:26 +0800 (CST) Received: from dggema772-chm.china.huawei.com (10.1.198.214) by DGGEMM401-HUB.china.huawei.com (10.3.20.209) with Microsoft SMTP Server (TLS) id 14.3.498.0; Fri, 29 Jan 2021 09:23:32 +0800 Received: from [10.169.42.93] (10.169.42.93) by dggema772-chm.china.huawei.com (10.1.198.214) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2106.2; Fri, 29 Jan 2021 09:23:32 +0800 Subject: Re: [PATCH v2] nvme-multipath: Early exit if no path is available To: Daniel Wagner References: <20210127103033.15318-1-dwagner@suse.de> <20210128075837.u5u56t23fq5gu6ou@beryllium.lan> <69575290-200e-b4a1-4269-c71e4c2cc37b@huawei.com> <20210128094004.erwnszjqcxlsi2kd@beryllium.lan> From: Chao Leng Message-ID: Date: Fri, 29 Jan 2021 09:23:31 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20210128094004.erwnszjqcxlsi2kd@beryllium.lan> Content-Language: en-US X-Originating-IP: [10.169.42.93] X-ClientProxiedBy: dggeme708-chm.china.huawei.com (10.1.199.104) To dggema772-chm.china.huawei.com (10.1.198.214) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210128_202338_275407_AE42512B X-CRM114-Status: GOOD ( 17.01 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sagi Grimberg , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Jens Axboe , Hannes Reinecke , Keith Busch , Christoph Hellwig Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 2021/1/28 17:40, Daniel Wagner wrote: > On Thu, Jan 28, 2021 at 05:18:56PM +0800, Chao Leng wrote: >> It is impossible to return NULL for nvme_next_ns(head, old). > > block nvme0n1: no usable path - requeuing I/O > block nvme0n1: no usable path - requeuing I/O > block nvme0n1: no usable path - requeuing I/O > block nvme0n1: no usable path - requeuing I/O > block nvme0n1: no usable path - requeuing I/O > block nvme0n1: no usable path - requeuing I/O > BUG: kernel NULL pointer dereference, address: 0000000000000068 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 8000000ff67bc067 P4D 8000000ff67bc067 PUD ff9ac9067 PMD 0 > Oops: 0000 [#1] SMP PTI > CPU: 23 PID: 15759 Comm: dt.21.15 Kdump: loaded Tainted: G E 5.3.18-0.gc9fe679-default #1 SLE15-SP2 (unreleased) > Hardware name: FUJITSU PRIMERGY RX2540 M2/D3289-B1, BIOS V5.0.0.11 R1.18.0 for D3289-B1x 02/06/2018 > RIP: 0010:nvme_ns_head_make_request+0x1d1/0x430 [nvme_core] > Code: 54 24 10 0f 84 c9 01 00 00 48 8b 54 24 10 48 83 ea 30 0f 84 ba 01 00 00 48 39 d0 0f 84 01 02 00 00 31 ff eb 05 48 39 d0 74 67 <48> 8b 72 68 83 e6 04 75 13 48 8b 72 68 83 e6 01 75 0a 48 8b 72 10 > RSP: 0018:ffffa69d08017af8 EFLAGS: 00010246 > RAX: ffff92f261d87800 RBX: ffff92fa555b0010 RCX: ffff92fa555bc570 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > RBP: 0000000000000001 R08: 0000000000001000 R09: 0000000000001000 > R10: ffffa69d080179a8 R11: ffff92f264f0c1c0 R12: ffff92f264f7f000 > R13: ffff92fa555b0000 R14: 0000000000000001 R15: 0000000000000000 > FS: 00007f3962bae700(0000) GS:ffff92f29ffc0000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000068 CR3: 0000000fd69a2002 CR4: 00000000003606e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > generic_make_request+0x121/0x300 > ? submit_bio+0x42/0x1c0 > submit_bio+0x42/0x1c0 > ext4_io_submit+0x49/0x60 [ext4] > ext4_writepages+0x625/0xe90 [ext4] > ? do_writepages+0x4b/0xe0 > ? ext4_mark_inode_dirty+0x1d0/0x1d0 [ext4] > do_writepages+0x4b/0xe0 > ? __generic_file_write_iter+0x192/0x1c0 > ? __filemap_fdatawrite_range+0xcb/0x100 > __filemap_fdatawrite_range+0xcb/0x100 > ? ext4_file_write_iter+0x128/0x3c0 [ext4] > file_write_and_wait_range+0x5e/0xb0 > __generic_file_fsync+0x22/0xb0 > ext4_sync_file+0x1f7/0x3c0 [ext4] > do_fsync+0x38/0x60 > __x64_sys_fsync+0x10/0x20 > do_syscall_64+0x5b/0x1e0 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > You can't see exactly where it dies but I followed the assembly to > nvme_round_robin_path(). Maybe it's not the initial nvme_next_ns(head, > old) which returns NULL but nvme_next_ns() is returning NULL eventually > (list_next_or_null_rcu()). So there is other bug cause nvme_next_ns abormal. I review the code about head->list and head->current_path, I find 2 bugs may cause the bug: First, I already send the patch. see: https://lore.kernel.org/linux-nvme/20210128033351.22116-1-lengchao@huawei.com/ Second, in nvme_ns_remove, list_del_rcu is before nvme_mpath_clear_current_path. This may cause "old" is deleted from the "head", but still use "old". I'm not sure there's any other consideration here, I will check it and try to fix it. > > And I have positive feedback, this patch fixes the above problem. Although adding check ns can fix the crash. There may still be other problems such as in __nvme_find_path which use list_for_each_entry_rcu. > > . > _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme