From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [IPv6:2a01:7e0:0:424::9]) by lore.proxmox.com (Postfix) with ESMTPS id 2204B1FF2A7 for ; Mon, 1 Jul 2024 14:08:23 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 3A18134E56; Mon, 1 Jul 2024 14:08:36 +0200 (CEST) Message-ID: <2a93b3bf-6358-4f70-93b0-9f760f612f36@proxmox.com> Date: Mon, 1 Jul 2024 14:07:58 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Fiona Ebner To: pve-devel@lists.proxmox.com References: <20240628090233.48637-1-f.ebner@proxmox.com> Content-Language: en-US In-Reply-To: <20240628090233.48637-1-f.ebner@proxmox.com> X-SPAM-LEVEL: Spam detection results: 0 AWL -0.062 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Subject: [pve-devel] applied: [PATCH qemu] async snapshot: fix crash with VirtIO block with iothread when not saving VM state X-BeenThere: pve-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox VE development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Proxmox VE development discussion Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: pve-devel-bounces@lists.proxmox.com Sender: "pve-devel" Am 28.06.24 um 11:02 schrieb Fiona Ebner: > As reported in the community forum [0], doing a snapshot without > saving the VM state for a VM with a VirtIO block device with iothread > would lead to an assertion failure [1] and thus crash. > > The issue is that vm_start() is called from the coroutine > qmp_savevm_end() which violates assumptions about graph locking down > the line. Factor out the part of qmp_savevm_end() that actually needs > to be a coroutine into a separate helper and turn qmp_savevm_end() > into a non-coroutine, so that it can call vm_start() safely. > > The issue is likely not new, but was exposed by the recent graph > locking rework introducing stricter checks. > > The issue does not occur when saving the VM state, because then the > non-coroutine process_savevm_finalize() will already call vm_start() > before qmp_savevm_end(). > > [0]: https://forum.proxmox.com/threads/149883/ > > [1]: > >> #0 0x00007353e6096e2c __pthread_kill_implementation (libc.so.6 + 0x8ae2c) >> #1 0x00007353e6047fb2 __GI_raise (libc.so.6 + 0x3bfb2) >> #2 0x00007353e6032472 __GI_abort (libc.so.6 + 0x26472) >> #3 0x00007353e6032395 __assert_fail_base (libc.so.6 + 0x26395) >> #4 0x00007353e6040eb2 __GI___assert_fail (libc.so.6 + 0x34eb2) >> #5 0x0000592002307bb3 bdrv_graph_rdlock_main_loop (qemu-system-x86_64 + 0x83abb3) >> #6 0x00005920022da455 bdrv_change_aio_context (qemu-system-x86_64 + 0x80d455) >> #7 0x00005920022da6cb bdrv_try_change_aio_context (qemu-system-x86_64 + 0x80d6cb) >> #8 0x00005920022fe122 blk_set_aio_context (qemu-system-x86_64 + 0x831122) >> #9 0x00005920021b7b90 virtio_blk_start_ioeventfd (qemu-system-x86_64 + 0x6eab90) >> #10 0x0000592002022927 virtio_bus_start_ioeventfd (qemu-system-x86_64 + 0x555927) >> #11 0x0000592002066cc4 vm_state_notify (qemu-system-x86_64 + 0x599cc4) >> #12 0x000059200205d517 vm_prepare_start (qemu-system-x86_64 + 0x590517) >> #13 0x000059200205d56b vm_start (qemu-system-x86_64 + 0x59056b) >> #14 0x00005920020a43fd qmp_savevm_end (qemu-system-x86_64 + 0x5d73fd) >> #15 0x00005920023f3749 qmp_marshal_savevm_end (qemu-system-x86_64 + 0x926749) >> #16 0x000059200242f1d8 qmp_dispatch (qemu-system-x86_64 + 0x9621d8) >> #17 0x000059200238fa98 monitor_qmp_dispatch (qemu-system-x86_64 + 0x8c2a98) >> #18 0x000059200239044e monitor_qmp_dispatcher_co (qemu-system-x86_64 + 0x8c344e) >> #19 0x000059200245359b coroutine_trampoline (qemu-system-x86_64 + 0x98659b) >> #20 0x00007353e605d9c0 n/a (libc.so.6 + 0x519c0) > > Signed-off-by: Fiona Ebner applied after receiving positive off-list feedback from Fabian and Wolfgang _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel