From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <f.ebner@proxmox.com> 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 E544669B28 for <pve-devel@lists.proxmox.com>; Wed, 28 Jul 2021 10:39:28 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id D364121F06 for <pve-devel@lists.proxmox.com>; Wed, 28 Jul 2021 10:38:58 +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 0115921EFD for <pve-devel@lists.proxmox.com>; Wed, 28 Jul 2021 10:38:57 +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 CA42842B26 for <pve-devel@lists.proxmox.com>; Wed, 28 Jul 2021 10:38:57 +0200 (CEST) From: Fabian Ebner <f.ebner@proxmox.com> To: pve-devel@lists.proxmox.com Date: Wed, 28 Jul 2021 10:38:54 +0200 Message-Id: <20210728083854.815295-1-f.ebner@proxmox.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.470 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 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] [PATCH kernel] backport fix for io_uring to prevent kernel panic X-BeenThere: pve-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox VE development discussion <pve-devel.lists.proxmox.com> List-Unsubscribe: <https://lists.proxmox.com/cgi-bin/mailman/options/pve-devel>, <mailto:pve-devel-request@lists.proxmox.com?subject=unsubscribe> List-Archive: <http://lists.proxmox.com/pipermail/pve-devel/> List-Post: <mailto:pve-devel@lists.proxmox.com> List-Help: <mailto:pve-devel-request@lists.proxmox.com?subject=help> List-Subscribe: <https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel>, <mailto:pve-devel-request@lists.proxmox.com?subject=subscribe> X-List-Received-Date: Wed, 28 Jul 2021 08:39:28 -0000 which could be triggered in some corner cases with (but most likely not limited to) LVM-backed QEMU guests using io_uring. Signed-off-by: Fabian Ebner <f.ebner@proxmox.com> --- ...lock-level-reissue-off-completion-pa.patch | 49 +++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 patches/kernel/0007-io_uring-don-t-block-level-reissue-off-completion-pa.patch diff --git a/patches/kernel/0007-io_uring-don-t-block-level-reissue-off-completion-pa.patch b/patches/kernel/0007-io_uring-don-t-block-level-reissue-off-completion-pa.patch new file mode 100644 index 0000000..ec9ce57 --- /dev/null +++ b/patches/kernel/0007-io_uring-don-t-block-level-reissue-off-completion-pa.patch @@ -0,0 +1,49 @@ +From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 +From: Fabian Ebner <f.ebner@proxmox.com> +Date: Wed, 28 Jul 2021 08:55:31 +0200 +Subject: [PATCH] io_uring: don't block level reissue off completion path + +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. + +This should be solved by having the -EAGAIN bubble back up the stack +as part of submission, but previous attempts at this failed and we're +not just quite there yet. Instead we currently use REQ_F_REISSUE to +handle this case. + +For now, catch it in io_rw_should_reissue() and prevent a reissue +from a bogus path. + +Upstream mail: +https://lore.kernel.org/io-uring/20210727165811.284510-3-axboe@kernel.dk/T/#u + +Originally-by: Jens Axboe <axboe@kernel.dk> +[backport] +Signed-off-by: Fabian Ebner <f.ebner@proxmox.com> +--- + fs/io_uring.c | 7 +++++++ + 1 file changed, 7 insertions(+) + +diff --git a/fs/io_uring.c b/fs/io_uring.c +index 2b86b413641a..11f615033c70 100644 +--- a/fs/io_uring.c ++++ b/fs/io_uring.c +@@ -2731,6 +2731,13 @@ static bool io_rw_reissue(struct io_kiocb *req, long res) + if (percpu_ref_is_dying(&req->ctx->refs)) + return false; + ++ /* ++ * Play it safe and assume not safe to re-import and reissue if we're ++ * not in the original thread group (or in task context). ++ */ ++ if (!same_thread_group(req->task, current) || !in_task()) ++ return false; ++ + lockdep_assert_held(&req->ctx->uring_lock); + + ret = io_sq_thread_acquire_mm_files(req->ctx, req); +-- +2.30.2 + -- 2.30.2