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Message-ID: <5348846F.6020405@redhat.com>
Date: Fri, 11 Apr 2014 20:10:23 -0400
From: Paolo Bonzini <pbonzini@...hat.com>
To: Fam Zheng <famz@...hat.com>, linux-kernel@...r.kernel.org
CC: linux-scsi@...r.kernel.org, kvm@...r.kernel.org,
stable@...r.kernel.org, James Bottomley <JBottomley@...allels.com>
Subject: Re: [PATCH] virtio-scsi: Skip setting affinity on uninitialized vq
Il 11/04/2014 03:23, Fam Zheng ha scritto:
> virtscsi_init calls virtscsi_remove_vqs on err, even before initializing
> the vqs. The latter calls virtscsi_set_affinity, so let's check the
> pointer there before setting affinity on it.
>
> This fixes a panic when setting device's num_queues=2 on RHEL 6.5:
>
> qemu-system-x86_64 ... \
> -device virtio-scsi-pci,id=scsi0,addr=0x13,...,num_queues=2 \
> -drive file=/stor/vm/dummy.raw,id=drive-scsi-disk,... \
> -device scsi-hd,drive=drive-scsi-disk,...
>
> [ 0.354734] scsi0 : Virtio SCSI HBA
> [ 0.379504] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
> [ 0.380141] IP: [<ffffffff814741ef>] __virtscsi_set_affinity+0x4f/0x120
> [ 0.380141] PGD 0
> [ 0.380141] Oops: 0000 [#1] SMP
> [ 0.380141] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.0+ #5
> [ 0.380141] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2007
> [ 0.380141] task: ffff88003c9f0000 ti: ffff88003c9f8000 task.ti: ffff88003c9f8000
> [ 0.380141] RIP: 0010:[<ffffffff814741ef>] [<ffffffff814741ef>] __virtscsi_set_affinity+0x4f/0x120
> [ 0.380141] RSP: 0000:ffff88003c9f9c08 EFLAGS: 00010256
> [ 0.380141] RAX: 0000000000000000 RBX: ffff88003c3a9d40 RCX: 0000000000001070
> [ 0.380141] RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000
> [ 0.380141] RBP: ffff88003c9f9c28 R08: 00000000000136c0 R09: ffff88003c801c00
> [ 0.380141] R10: ffffffff81475229 R11: 0000000000000008 R12: 0000000000000000
> [ 0.380141] R13: ffffffff81cc7ca8 R14: ffff88003cac3d40 R15: ffff88003cac37a0
> [ 0.380141] FS: 0000000000000000(0000) GS:ffff88003e400000(0000) knlGS:0000000000000000
> [ 0.380141] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> [ 0.380141] CR2: 0000000000000020 CR3: 0000000001c0e000 CR4: 00000000000006f0
> [ 0.380141] Stack:
> [ 0.380141] ffff88003c3a9d40 0000000000000000 ffff88003cac3d80 ffff88003cac3d40
> [ 0.380141] ffff88003c9f9c48 ffffffff814742e8 ffff88003c26d000 ffff88003c26d000
> [ 0.380141] ffff88003c9f9c68 ffffffff81474321 ffff88003c26d000 ffff88003c3a9d40
> [ 0.380141] Call Trace:
> [ 0.380141] [<ffffffff814742e8>] virtscsi_set_affinity+0x28/0x40
> [ 0.380141] [<ffffffff81474321>] virtscsi_remove_vqs+0x21/0x50
> [ 0.380141] [<ffffffff81475231>] virtscsi_init+0x91/0x240
> [ 0.380141] [<ffffffff81365290>] ? vp_get+0x50/0x70
> [ 0.380141] [<ffffffff81475544>] virtscsi_probe+0xf4/0x280
> [ 0.380141] [<ffffffff81363ea5>] virtio_dev_probe+0xe5/0x140
> [ 0.380141] [<ffffffff8144c669>] driver_probe_device+0x89/0x230
> [ 0.380141] [<ffffffff8144c8ab>] __driver_attach+0x9b/0xa0
> [ 0.380141] [<ffffffff8144c810>] ? driver_probe_device+0x230/0x230
> [ 0.380141] [<ffffffff8144c810>] ? driver_probe_device+0x230/0x230
> [ 0.380141] [<ffffffff8144ac1c>] bus_for_each_dev+0x8c/0xb0
> [ 0.380141] [<ffffffff8144c499>] driver_attach+0x19/0x20
> [ 0.380141] [<ffffffff8144bf28>] bus_add_driver+0x198/0x220
> [ 0.380141] [<ffffffff8144ce9f>] driver_register+0x5f/0xf0
> [ 0.380141] [<ffffffff81d27c91>] ? spi_transport_init+0x79/0x79
> [ 0.380141] [<ffffffff8136403b>] register_virtio_driver+0x1b/0x30
> [ 0.380141] [<ffffffff81d27d19>] init+0x88/0xd6
> [ 0.380141] [<ffffffff81d27c18>] ? scsi_init_procfs+0x5b/0x5b
> [ 0.380141] [<ffffffff81ce88a7>] do_one_initcall+0x7f/0x10a
> [ 0.380141] [<ffffffff81ce8aa7>] kernel_init_freeable+0x14a/0x1de
> [ 0.380141] [<ffffffff81ce8b3b>] ? kernel_init_freeable+0x1de/0x1de
> [ 0.380141] [<ffffffff817dec20>] ? rest_init+0x80/0x80
> [ 0.380141] [<ffffffff817dec29>] kernel_init+0x9/0xf0
> [ 0.380141] [<ffffffff817e68fc>] ret_from_fork+0x7c/0xb0
> [ 0.380141] [<ffffffff817dec20>] ? rest_init+0x80/0x80
> [ 0.380141] RIP [<ffffffff814741ef>] __virtscsi_set_affinity+0x4f/0x120
> [ 0.380141] RSP <ffff88003c9f9c08>
> [ 0.380141] CR2: 0000000000000020
> [ 0.380141] ---[ end trace 8074b70c3d5e1d73 ]---
> [ 0.475018] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009
> [ 0.475018]
> [ 0.475068] Kernel Offset: 0x0 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffff9fffffff)
> [ 0.475068] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009
>
> Signed-off-by: Fam Zheng <famz@...hat.com>
> ---
> drivers/scsi/virtio_scsi.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index 16bfd50..3019267 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -750,8 +750,12 @@ static void __virtscsi_set_affinity(struct virtio_scsi *vscsi, bool affinity)
>
> vscsi->affinity_hint_set = true;
> } else {
> - for (i = 0; i < vscsi->num_queues; i++)
> + for (i = 0; i < vscsi->num_queues; i++) {
> + if (!vscsi->req_vqs[i].vq) {
> + continue;
> + }
> virtqueue_set_affinity(vscsi->req_vqs[i].vq, -1);
> + }
>
> vscsi->affinity_hint_set = false;
> }
>
You put the if inside the loop, but it's really all or nothing since the
failure point is find_vqs.
Not a problem though; the queues are few and this is not a hot path anyway.
Acked-by: Paolo Bonzini <pbonzini@...hat.com>
Paolo
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