From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CDE8029ACF7 for ; Tue, 21 Apr 2026 21:50:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776808213; cv=none; b=HAHcPFLanhsd2BEzhIqH0ekzLRwBy5HY10dQmqPv2ZIVYguDl6hknHsNvPDz0sRE1gexJZ2R/CpmI8ZI0Bt249ZGhx4xYkBHNYd8F1kXVXIiuRv7g4oIgr4VmCyuE0o+/N29Fc18RY63WywwdpSLYSY7VaP9eUC1MIe/Jl+KOm4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776808213; c=relaxed/simple; bh=0nUUR8I2aImDiVliu8mh26Afgb7OT3eAV4nQeOJ9X20=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=aFNyCI+0PcUnf/tL2xO3DTKFrZZO4isVtTLb/J4a6k94EmnFIfHPvJn2NASUZODUUi4wlMyhIYVoyBzwvu2fms9RFvF6mf5yv8p2KZNhjNQhz4EV8mTUnmwS7925zx2akUAM5aZDezg8gh4CIusOkDOPgyhyVYq/wO5CHS/Jubw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=X++hpWdn; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=VoVqWeaU; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="X++hpWdn"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="VoVqWeaU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1776808210; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UkT6yxz2rU1VLImTOoGRlih0ZljZA1XkvvTLYlYGezA=; b=X++hpWdnDZH19D/1Z8f+Gxrs3C6ocjshuyWIJChZ5eKfqo3WgpTNIgGFOU8iKKxi7Q08Xp kFOISDpHqDsLBxlCEJmXsCo+21TfHgtg3mqdV8S3Gl3C/FEgLY7MfDzbZK5a+uXDz6qBWd afOKXXUTKR5ZgmoWpX8b0v/dbzXJixY= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-27-MkGwiiSbMyCyZW5r56go_Q-1; Tue, 21 Apr 2026 17:50:09 -0400 X-MC-Unique: MkGwiiSbMyCyZW5r56go_Q-1 X-Mimecast-MFC-AGG-ID: MkGwiiSbMyCyZW5r56go_Q_1776808208 Received: by mail-wr1-f72.google.com with SMTP id ffacd0b85a97d-43d77286244so3114653f8f.1 for ; Tue, 21 Apr 2026 14:50:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1776808208; x=1777413008; darn=vger.kernel.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=UkT6yxz2rU1VLImTOoGRlih0ZljZA1XkvvTLYlYGezA=; b=VoVqWeaU+7/zhkPjls3XAMxEk0JbhPtoVexjSy0AOSOVuSK463okYDMCQ6dQ02mfv+ Tfo4LUA/nKZot+oSLR/yK2ETtGV7/vL9abKtAzDQHQnoKJ8Hu3KyRzQc03CT0TuadxGd Z+DNf3dSCAlO8x8ZMhRpbhq1srr+Vj6JXstxX4wiS0tFPOn9woP+aIyq0lE3Oupuw6r8 //eIdnUgwO940l8Q6ZXfjOTHQCqkyRVZ4Aa8hnF1YJZHC1flpWzL93yDcHLeeoFLbgR2 GI+iMn1ydl2M43b6RXIpyGHv4YhXzC9lHSafOy3XOE8MBTmkoIZsfOxXXb3Hg7RxROYH KViw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776808208; x=1777413008; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=UkT6yxz2rU1VLImTOoGRlih0ZljZA1XkvvTLYlYGezA=; b=UYfLu/T77CiAPV2XiQy02MVjXIRuud43qeThB6JlNrWkX2GUTCiEFuR84FWWH/3CyK HvV9rEfQAOLzMnUEXiN9db6nBKDCYNwymrMygvof4SfZeQUO18pPLPJDUkxdnMa6A6JA PbUbYryBrt4IsLYnUnYqKgblNlOuoIfN+YZFtpMWQaUEZe9cLovxIpcb3s7xYIqhqCPN LuywaGK7oD7Mb9QJr+w2oD2NSn6c1sQTtExTtWDYXbmVGrmHmYBQIw1ISR5Dr2AVqOPm im2mUbPtIJ1FDvLC6Mqp160NjUoazstd8MwqD/SujLgm6OqjdbctTbhltf/aGCr4gR6X HLkg== X-Forwarded-Encrypted: i=1; AFNElJ+rVJyScZiHVfhQkUyfJnMpO55KZufOguwa/z7sex5t2pkShmy6ndJY0zRqPfVS98DuIQa9lPjyxQfex0g=@vger.kernel.org X-Gm-Message-State: AOJu0Yzeg0+yuZi30cSKVK48JmYZiAy5rr2drA5WqPmq5SYS376KAxxG ynEA+gdfhMuMnaeyxtCsv6un328RT1i0c2A/swjXsNnt9O0vyRFR7zyRAqLvRpfZKzuuMVwHrDs SsQ7iWCcN8Vs886q9VXoFh4PRMCQ6nEqjkmRJFEW1KI/VT+4iMaAgPV84pcwV83DClg== X-Gm-Gg: AeBDies2Vq08slhULb6AwtC2F8V3ZyQrmsYeeLFPdU2SO8Zy7XKCIfhXqExs8xHPeZk JtoD+ybq2m/EqQQVE8dLgvPjEwgYJuZxp6jD4cxluuLahANDtC9FecOCfc3x2HUsc47Coq6ecr8 g2BDnE9d1we8tGMQpcvEK/QJ8jlSJt9KroLb0JC1uEFhx/ZM6MbCSjKysWqczZqbB7bq8MrBiTS B7Kx/md1C+3i53vO7BW1+9f1Ti1ZpHNuhIowaeXulFOif4ZXcJ/ITv+0R91Z27ILYmHNpm8kXwW VVozBRCMoMrzUR1Rf3aGim2PF011OIfXYNLGVc1z+CN4q10sjlI3Tf2uRiwR2twv98fZ10rgQmK teMSO/T7nlQ4uhWdaWDxgbD58+Er6ee6kX+mGNFkwsYuTiLtRUWHYGw== X-Received: by 2002:a05:6000:2887:b0:43f:ea91:63ff with SMTP id ffacd0b85a97d-43fea916442mr23873614f8f.10.1776808207988; Tue, 21 Apr 2026 14:50:07 -0700 (PDT) X-Received: by 2002:a05:6000:2887:b0:43f:ea91:63ff with SMTP id ffacd0b85a97d-43fea916442mr23873587f8f.10.1776808207506; Tue, 21 Apr 2026 14:50:07 -0700 (PDT) Received: from redhat.com (IGLD-80-230-25-21.inter.net.il. [80.230.25.21]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43fe4e4d5b1sm44523269f8f.30.2026.04.21.14.50.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Apr 2026 14:50:07 -0700 (PDT) Date: Tue, 21 Apr 2026 17:50:04 -0400 From: "Michael S. Tsirkin" To: Link Lin Cc: jasowang@redhat.com, xuanzhuo@linux.alibaba.com, eperezma@redhat.com, jiaqiyan@google.com, rientjes@google.com, weixugc@google.com, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v1] virtio_pci: only store successfully populated virtio_pci_vq_info Message-ID: <20260421174945-mutt-send-email-mst@kernel.org> References: <20260407212521.934620-1-linkl@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Tue, Apr 21, 2026 at 02:24:16PM -0700, Link Lin wrote: > Hi everyone, > > Friendly ping on this RFC patch. Please let me know if anyone has had a chance > to look at this, or if any changes are needed. > > Thanks, > Link > > On Tue, Apr 7, 2026 at 2:25 PM Link Lin wrote: > > In environments where free page reporting is disabled, a kernel > panic is triggered when tearing down the virtio_balloon module: > >   [12261.808190] Call trace: >   [12261.808471]  __list_del_entry_valid_or_report+0x18/0xe0 >   [12261.809064]  vp_del_vqs+0x12c/0x270 >   [12261.809462]  remove_common+0x80/0x98 [virtio_balloon] >   [12261.810034]  virtballoon_remove+0xfc/0x158 [virtio_balloon] >   [12261.810663]  virtio_dev_remove+0x68/0xf8 >   [12261.811108]  device_release_driver_internal+0x17c/0x278 >   [12261.811701]  driver_detach+0xd4/0x138 >   [12261.812117]  bus_remove_driver+0x90/0xd0 >   [12261.812562]  driver_unregister+0x40/0x70 >   [12261.813006]  unregister_virtio_driver+0x20/0x38 >   [12261.813518]  cleanup_module+0x20/0x7a8 [virtio_balloon] >   [12261.814109]  __arm64_sys_delete_module+0x278/0x3d0 >   [12261.814654]  invoke_syscall+0x5c/0x120 >   [12261.815086]  el0_svc_common+0x90/0xf8 >   [12261.815506]  do_el0_svc+0x2c/0x48 >   [12261.815883]  el0_svc+0x3c/0xa8 >   [12261.816235]  el0t_64_sync_handler+0x8c/0x108 >   [12261.816724]  el0t_64_sync+0x198/0x1a0 > > The issue originates in vp_find_vqs_intx(). It kzalloc_objs() based > on the nvqs count provided by the caller, virtio_balloon::init_vqs(). > However, it is not always the case that all nvqs number of > virtio_pci_vq_info objects will be properly populated. > > For example, when VIRTIO_BALLOON_F_FREE_PAGE_HINT is absent, the > VIRTIO_BALLOON_VQ_FREE_PAGE-th item in the vp_dev->vqs array is > actually never populated, and is still a zeroe-initialized > virtio_pci_vq_info object, which is eventually going to trigger > a __list_del_entry_valid_or_report() crash. > > Tested by applying this patch to a guest VM kernel with the > VIRTIO_BALLOON_F_REPORTING feature enabled and the > VIRTIO_BALLOON_F_FREE_PAGE_HINT feature disabled. > Without this patch, unloading the virtio_balloon module triggers a panic. > With this patch, no panic is observed. > > The fix is to use queue_idx to handle the case that vp_find_vqs_intx() > skips vp_setup_vq() when caller provided null vqs_info[i].name, when > the caller doesn't populate all nvqs number of virtqueue_info objects. > Invariantly queue_idx is the correct index to store a successfully > created and populated virtio_pci_vq_info object. As a result, now > a virtio_pci_device object only stores queue_idx number of valid > virtio_pci_vq_info objects in its vqs array when the for-loop over > nvqs finishes (of course, without goto out_del_vqs). > > vp_find_vqs_msix() has similar issue, so fix it in the same way. > > This patch is marked as RFC because we are uncertain if any virtio-pci > code implicitly requires virtio_pci_device's vqs array to always > contain nvqs number of virtio_pci_vq_info objects, and to store > zero-initialized virtio_pci_vq_info objects. We have not observed > any issues in our testing, but insights or alternatives are welcome! > > Signed-off-by: Link Lin > Co-developed-by: Jiaqi Yan > Signed-off-by: Jiaqi Yan > --- >  drivers/virtio/virtio_pci_common.c | 10 ++++++---- >  1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/ > virtio_pci_common.c > index da97b6a988de..9b32301529e5 100644 > --- a/drivers/virtio/virtio_pci_common.c > +++ b/drivers/virtio/virtio_pci_common.c > @@ -423,14 +423,15 @@ static int vp_find_vqs_msix(struct virtio_device > *vdev, unsigned int nvqs, >                         vqs[i] = NULL; >                         continue; >                 } > -               vqs[i] = vp_find_one_vq_msix(vdev, queue_idx++, vqi-> > callback, > +               vqs[i] = vp_find_one_vq_msix(vdev, queue_idx, vqi-> > callback, >                                              vqi->name, vqi->ctx, false, >                                              &allocated_vectors, > vector_policy, > -                                            &vp_dev->vqs[i]); > +                                            &vp_dev->vqs[queue_idx]); >                 if (IS_ERR(vqs[i])) { >                         err = PTR_ERR(vqs[i]); >                         goto error_find; >                 } > +               ++queue_idx; >         } > >         if (!avq_num) > @@ -485,13 +486,14 @@ static int vp_find_vqs_intx(struct virtio_device > *vdev, unsigned int nvqs, >                         vqs[i] = NULL; >                         continue; >                 } > -               vqs[i] = vp_setup_vq(vdev, queue_idx++, vqi->callback, > +               vqs[i] = vp_setup_vq(vdev, queue_idx, vqi->callback, >                                      vqi->name, vqi->ctx, > -                                    VIRTIO_MSI_NO_VECTOR, &vp_dev->vqs > [i]); > +                                    VIRTIO_MSI_NO_VECTOR, &vp_dev->vqs > [queue_idx]); >                 if (IS_ERR(vqs[i])) { >                         err = PTR_ERR(vqs[i]); >                         goto out_del_vqs; >                 } > +               ++queue_idx; >         } > >         if (!avq_num) > -- > 2.53.0.1213.gd9a14994de-goog > I have this in my tree: https://lore.kernel.org/all/20260315141808.547081-1-ammarfaizi2@openresty.com/ same? -- MST