From nobody Sun Sep 14 14:51:22 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 42C1DC05027 for ; Fri, 20 Jan 2023 22:12:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230025AbjATWMr (ORCPT ); Fri, 20 Jan 2023 17:12:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60704 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229989AbjATWMh (ORCPT ); Fri, 20 Jan 2023 17:12:37 -0500 Received: from mail-io1-xd36.google.com (mail-io1-xd36.google.com [IPv6:2607:f8b0:4864:20::d36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F12310AA4 for ; Fri, 20 Jan 2023 14:12:36 -0800 (PST) Received: by mail-io1-xd36.google.com with SMTP id j1so3111479iob.6 for ; Fri, 20 Jan 2023 14:12:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digitalocean.com; s=google; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=4THOFKr/oi12Lh9VLujYmInaKqJLT8dgCNKdQB2cfmk=; b=T4T5wgg++tuZ/vEq0fZnEjrnICkN93HtNwM8BOci4baJ4tNoZUO7qzGEVTNBfA+zQu n+V3DygwoipkiGcrdikPsPg9EX2QlA0RNlOvWazocCNMxG+ELMunhJNN2QxkSiTowOD9 0wWjNg+idMoxJJ1ObfK0zxrJuNMwQRT2ae9oY= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=4THOFKr/oi12Lh9VLujYmInaKqJLT8dgCNKdQB2cfmk=; b=r5f6PrhkKhtzxUORoIT8SfKfK1lxH3LquJdDgArWlCo/IeFOdn0fn/n0BTnItz9ANR D0hzrSLF5VR6GRmEvjd1+51uax34oTegxO47Sodap39OLrtDTj7x+m5dK2pXqVJHIrgR X6AhueWTsj9ILcot4r4PP9mR7fp9bj3wMlnaxN0a91QqpgevOgwrJP0XzBfpEYgqmDSN NFpa5OUgN4l12teVtK2aia1ZzC2LOCzsUeRogtOKKlCdUarQ2Rjh2LxJlY7QGiSTTsdV 7MNSNATBUGh3o2/A1i/M68QGKoCbSX0FMNxNE/DxkFH/RaD3RfUo3RPuRA4dGAFH9JD7 +3Fw== X-Gm-Message-State: AFqh2ko7HNJNvJFjjWAebWHiLWfEI/dKs1XZjwoY8hK0/Vd5qxjDvMLA ukhcpcHVrzUCbPhz8z1qMPHDXA== X-Google-Smtp-Source: AMrXdXuYH0nZSV1qNftw1CzohAHNXptoGk5ziEa4Bpij01Z0mb6PK5Xk5Fi9HVzcgmqxNrAazaw+Lg== X-Received: by 2002:a5e:df08:0:b0:704:6e8d:4891 with SMTP id f8-20020a5edf08000000b007046e8d4891mr12238768ioq.3.1674252755532; Fri, 20 Jan 2023 14:12:35 -0800 (PST) Received: from localhost ([136.37.131.79]) by smtp.gmail.com with ESMTPSA id j5-20020a5d93c5000000b006bba42f7822sm13342047ioo.52.2023.01.20.14.12.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Jan 2023 14:12:35 -0800 (PST) From: "Seth Forshee (DigitalOcean)" X-Google-Original-From: "Seth Forshee (DigitalOcean)" Date: Fri, 20 Jan 2023 16:12:22 -0600 Subject: [PATCH 2/2] vhost: check for pending livepatches from vhost worker kthreads MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20230120-vhost-klp-switching-v1-2-7c2b65519c43@kernel.org> References: <20230120-vhost-klp-switching-v1-0-7c2b65519c43@kernel.org> In-Reply-To: <20230120-vhost-klp-switching-v1-0-7c2b65519c43@kernel.org> To: Petr Mladek , Jason Wang , "Michael S. Tsirkin" , Jiri Kosina , Miroslav Benes , Joe Lawrence , Josh Poimboeuf Cc: virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, "Seth Forshee (DigitalOcean)" , netdev@vger.kernel.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org X-Mailer: b4 0.10.1 X-Developer-Signature: v=1; a=openpgp-sha256; l=1164; i=sforshee@kernel.org; h=from:subject:message-id; bh=4/niAYH6EV14H83dRR2LugTxSHfcyLm3BmgkkAhqns4=; b=owEBbQGS/pANAwAKAVMDma7l9DHJAcsmYgBjyxHO/ViIOpErIY20s4GDksHjnp6o0DAE12QlN8dK hhzTEKaJATMEAAEKAB0WIQSQnt+rKAvnETy4Hc9TA5mu5fQxyQUCY8sRzgAKCRBTA5mu5fQxyfOWB/ 0WuOaZX+X5hCUgwSQTrkcv8eFNZr4ccIejTsTobwcs5msz5xGxh69uUHYc01UIvAoWd1KmcPNRwrUQ L1d3KILMoPNtB9E1KUGutwyCKQ+II25ZpJEN4NwvS1ne/2RTuYLC3JAE/5KXJBPrgkYtamqmAlQigj qPsmksCw5XYnJL8mlFNPnKi7mRUrO5wzG6Nvfklg6ueJJ0RjChqfxx7ihMiyz/i6NYxwnWrdb81ThR bvCgejkYkOCxXGU141uIoNj8L/+LxSJt7V4fBLFhWS7StagI41mGFFMKQDYshldbxo3ni4dt209Pxc r41Nzfigh02pcyKBNKotRlwsrmhIEy X-Developer-Key: i=sforshee@kernel.org; a=openpgp; fpr=2ABCA7498D83E1D32D51D3B5AB4800A62DB9F73A Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Livepatch relies on stack checking of sleeping tasks to switch kthreads, so a busy kthread can block a livepatch transition indefinitely. We've seen this happen fairly often with busy vhost kthreads. Add a check to call klp_switch_current() from vhost_worker() when a livepatch is pending. In testing this allowed vhost kthreads to switch immediately when they had previously blocked livepatch transitions for long periods of time. Signed-off-by: Seth Forshee (DigitalOcean) --- drivers/vhost/vhost.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index cbe72bfd2f1f..d8624f1f2d64 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -30,6 +30,7 @@ #include #include #include +#include =20 #include "vhost.h" =20 @@ -366,6 +367,9 @@ static int vhost_worker(void *data) if (need_resched()) schedule(); } + + if (unlikely(klp_patch_pending(current))) + klp_switch_current(); } kthread_unuse_mm(dev->mm); return 0; --=20 b4 0.10.1