From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id D297F69F29 for ; Thu, 29 Jul 2021 10:37:17 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id C6D4F2CBBA for ; Thu, 29 Jul 2021 10:37:17 +0200 (CEST) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [94.136.29.106]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS id ECE552CBAC for ; Thu, 29 Jul 2021 10:37:16 +0200 (CEST) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id BCCF342C2F for ; Thu, 29 Jul 2021 10:37:16 +0200 (CEST) Message-ID: <0b3c268c-ac7e-a619-1784-fd1d539e58f1@proxmox.com> Date: Thu, 29 Jul 2021 10:37:14 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.0 Content-Language: en-GB To: Proxmox VE development discussion , Fabian Ebner References: <20210728105555.1225184-1-f.ebner@proxmox.com> From: Thomas Lamprecht In-Reply-To: <20210728105555.1225184-1-f.ebner@proxmox.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.530 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment NICE_REPLY_A -0.277 Looks like a legit reply (A) SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Subject: Re: [pve-devel] [PATCH qemu] block/io_uring: resubmit when result is -EAGAIN 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: , X-List-Received-Date: Thu, 29 Jul 2021 08:37:17 -0000 On 28/07/2021 12:55, Fabian Ebner wrote: > Quoting from [0]: > > Some setups, like SCSI, can throw spurious -EAGAIN off the softirq > completion path. Normally we expect this to happen inline as part > of submission, but apparently SCSI has a weird corner case where it > can happen as part of normal completions. > > Host kernels without patch [0] can panic when this happens [1], and > resubmitting makes the panic more likely. On the other hand, for > kernels with patch [0], resubmitting ensures that a block job is not > aborted just because of such spurious errors. In particular, this > should fix the problem reported in [2] with PBS backups of LVM-backed > VMs. > > [0]: https://lore.kernel.org/io-uring/20210727165811.284510-3-axboe@kernel.dk/T/#u > > [1]: > #9 [ffffb732000c8b70] asm_exc_page_fault at ffffffffa4800ade > #10 [ffffb732000c8bf8] io_prep_async_work at ffffffffa3d89c16 > #11 [ffffb732000c8c50] io_rw_reissue at ffffffffa3d8b2e1 > #12 [ffffb732000c8c78] io_complete_rw at ffffffffa3d8baa8 > #13 [ffffb732000c8c98] blkdev_bio_end_io at ffffffffa3d62a80 > #14 [ffffb732000c8cc8] bio_endio at ffffffffa3f4e800 > #15 [ffffb732000c8ce8] dec_pending at ffffffffa432f854 > #16 [ffffb732000c8d30] clone_endio at ffffffffa433170c > #17 [ffffb732000c8d70] bio_endio at ffffffffa3f4e800 > #18 [ffffb732000c8d90] blk_update_request at ffffffffa3f53a37 > #19 [ffffb732000c8dd0] scsi_end_request at ffffffffa4233a5c > #20 [ffffb732000c8e08] scsi_io_completion at ffffffffa423432c > #21 [ffffb732000c8e58] scsi_finish_command at ffffffffa422c527 > #22 [ffffb732000c8e88] scsi_softirq_done at ffffffffa42341e4 > > [2]: https://forum.proxmox.com/threads/backup-job-failed-with-err-11-on-2-of-6-vms.92568/ > > Signed-off-by: Fabian Ebner > --- > > Mail sent upstream: > https://lists.nongnu.org/archive/html/qemu-devel/2021-07/msg06765.html I see that it's already reviewed (at least after the maintainers got CC'd ;)) and OK besides some missing comments, so great work! Can you please send this here as "patch of a patch" to be applied on pve-qemu though? Would make it easier and commit the actual author to that git history too. I'd put it into the `debian/patches/extra` folder there, it'll be gone again when updating the submodule to a future QEMU 6.1 anyway, and it's not PVE specific.