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Dragos Tatulea 73790bdfba vdpa/mlx5: Fix hang when cvq commands are triggered during device unregister
Currently the vdpa device is unregistered after the workqueue that
processes vq commands is disabled. However, the device unregister
process can still send commands to the cvq (a vlan delete for example)
which leads to a hang because the handing workqueue has been disabled
and the command never finishes:

 [ 2263.095764] rcu: INFO: rcu_sched self-detected stall on CPU
 [ 2263.096307] rcu:        9-....: (5250 ticks this GP) idle=dac4/1/0x4000000000000000 softirq=111009/111009 fqs=2544
 [ 2263.097154] rcu:        (t=5251 jiffies g=393549 q=347 ncpus=10)
 [ 2263.097648] CPU: 9 PID: 94300 Comm: kworker/u20:2 Not tainted 6.3.0-rc6_for_upstream_min_debug_2023_04_14_00_02 #1
 [ 2263.098535] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
 [ 2263.099481] Workqueue: mlx5_events mlx5_vhca_state_work_handler [mlx5_core]
 [ 2263.100143] RIP: 0010:virtnet_send_command+0x109/0x170
 [ 2263.100621] Code: 1d df f5 ff 85 c0 78 5c 48 8b 7b 08 e8 d0 c5 f5 ff 84 c0 75 11 eb 22 48 8b 7b 08 e8 01 b7 f5 ff 84 c0 75 15 f3 90 48 8b 7b 08 <48> 8d 74 24 04 e8 8d c5 f5 ff 48 85 c0 74 de 48 8b 83 f8 00 00 00
 [ 2263.102148] RSP: 0018:ffff888139cf36e8 EFLAGS: 00000246
 [ 2263.102624] RAX: 0000000000000000 RBX: ffff888166bea940 RCX: 0000000000000001
 [ 2263.103244] RDX: 0000000000000000 RSI: ffff888139cf36ec RDI: ffff888146763800
 [ 2263.103864] RBP: ffff888139cf3710 R08: ffff88810d201000 R09: 0000000000000000
 [ 2263.104473] R10: 0000000000000002 R11: 0000000000000003 R12: 0000000000000002
 [ 2263.105082] R13: 0000000000000002 R14: ffff888114528400 R15: ffff888166bea000
 [ 2263.105689] FS:  0000000000000000(0000) GS:ffff88852cc80000(0000) knlGS:0000000000000000
 [ 2263.106404] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 [ 2263.106925] CR2: 00007f31f394b000 CR3: 000000010615b006 CR4: 0000000000370ea0
 [ 2263.107542] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 [ 2263.108163] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 [ 2263.108769] Call Trace:
 [ 2263.109059]  <TASK>
 [ 2263.109320]  ? check_preempt_wakeup+0x11f/0x230
 [ 2263.109750]  virtnet_vlan_rx_kill_vid+0x5a/0xa0
 [ 2263.110180]  vlan_vid_del+0x9c/0x170
 [ 2263.110546]  vlan_device_event+0x351/0x760 [8021q]
 [ 2263.111004]  raw_notifier_call_chain+0x41/0x60
 [ 2263.111426]  dev_close_many+0xcb/0x120
 [ 2263.111808]  unregister_netdevice_many_notify+0x130/0x770
 [ 2263.112297]  ? wq_worker_running+0xa/0x30
 [ 2263.112688]  unregister_netdevice_queue+0x89/0xc0
 [ 2263.113128]  unregister_netdev+0x18/0x20
 [ 2263.113512]  virtnet_remove+0x4f/0x230
 [ 2263.113885]  virtio_dev_remove+0x31/0x70
 [ 2263.114273]  device_release_driver_internal+0x18f/0x1f0
 [ 2263.114746]  bus_remove_device+0xc6/0x130
 [ 2263.115146]  device_del+0x173/0x3c0
 [ 2263.115502]  ? kernfs_find_ns+0x35/0xd0
 [ 2263.115895]  device_unregister+0x1a/0x60
 [ 2263.116279]  unregister_virtio_device+0x11/0x20
 [ 2263.116706]  device_release_driver_internal+0x18f/0x1f0
 [ 2263.117182]  bus_remove_device+0xc6/0x130
 [ 2263.117576]  device_del+0x173/0x3c0
 [ 2263.117929]  ? vdpa_dev_remove+0x20/0x20 [vdpa]
 [ 2263.118364]  device_unregister+0x1a/0x60
 [ 2263.118752]  mlx5_vdpa_dev_del+0x4c/0x80 [mlx5_vdpa]
 [ 2263.119232]  vdpa_match_remove+0x21/0x30 [vdpa]
 [ 2263.119663]  bus_for_each_dev+0x71/0xc0
 [ 2263.120054]  vdpa_mgmtdev_unregister+0x57/0x70 [vdpa]
 [ 2263.120520]  mlx5v_remove+0x12/0x20 [mlx5_vdpa]
 [ 2263.120953]  auxiliary_bus_remove+0x18/0x30
 [ 2263.121356]  device_release_driver_internal+0x18f/0x1f0
 [ 2263.121830]  bus_remove_device+0xc6/0x130
 [ 2263.122223]  device_del+0x173/0x3c0
 [ 2263.122581]  ? devl_param_driverinit_value_get+0x29/0x90
 [ 2263.123070]  mlx5_rescan_drivers_locked+0xc4/0x2d0 [mlx5_core]
 [ 2263.123633]  mlx5_unregister_device+0x54/0x80 [mlx5_core]
 [ 2263.124169]  mlx5_uninit_one+0x54/0x150 [mlx5_core]
 [ 2263.124656]  mlx5_sf_dev_remove+0x45/0x90 [mlx5_core]
 [ 2263.125153]  auxiliary_bus_remove+0x18/0x30
 [ 2263.125560]  device_release_driver_internal+0x18f/0x1f0
 [ 2263.126052]  bus_remove_device+0xc6/0x130
 [ 2263.126451]  device_del+0x173/0x3c0
 [ 2263.126815]  mlx5_sf_dev_remove+0x39/0xf0 [mlx5_core]
 [ 2263.127318]  mlx5_sf_dev_state_change_handler+0x178/0x270 [mlx5_core]
 [ 2263.127920]  blocking_notifier_call_chain+0x5a/0x80
 [ 2263.128379]  mlx5_vhca_state_work_handler+0x151/0x200 [mlx5_core]
 [ 2263.128951]  process_one_work+0x1bb/0x3c0
 [ 2263.129355]  ? process_one_work+0x3c0/0x3c0
 [ 2263.129766]  worker_thread+0x4d/0x3c0
 [ 2263.130140]  ? process_one_work+0x3c0/0x3c0
 [ 2263.130548]  kthread+0xb9/0xe0
 [ 2263.130895]  ? kthread_complete_and_exit+0x20/0x20
 [ 2263.131349]  ret_from_fork+0x1f/0x30
 [ 2263.131717]  </TASK>

The fix is to disable and destroy the workqueue after the device
unregister. It is expected that vhost will not trigger kicks after
the unregister. But even if it would, the wq is disabled already by
setting the pointer to NULL (done so in the referenced commit).

Fixes: ad6dc1daaf ("vdpa/mlx5: Avoid processing works if workqueue was destroyed")
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Message-Id: <20230516095800.3549932-1-dtatulea@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Acked-by: Jason Wang <jasowang@redhat.com>
2023-06-08 15:43:08 -04:00
arch ARM: 2023-06-04 07:16:53 -04:00
block block: fix revalidate performance regression 2023-05-29 08:40:32 -06:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto This push fixes the following problems: 2023-05-07 10:57:14 -07:00
Documentation Char/Misc driver fixes for 6.4-rc5 2023-06-04 08:32:30 -04:00
drivers vdpa/mlx5: Fix hang when cvq commands are triggered during device unregister 2023-06-08 15:43:08 -04:00
fs Fix an ext4 regression which landed during the 6.4 merge window. 2023-06-02 17:25:22 -04:00
include media fixes for v6.4-rc5 2023-06-04 09:10:43 -04:00
init Objtool changes for v6.4: 2023-04-28 14:02:54 -07:00
io_uring io_uring: undeprecate epoll_ctl support 2023-05-26 20:22:41 -06:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel Probes fixes for 6.4-rc4: 2023-06-03 08:23:16 -04:00
lib test_firmware: fix the memory leak of the allocated firmware buffer 2023-05-31 20:31:07 +01:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: page_table_check: Ensure user pages are not slab pages 2023-05-29 16:14:28 +01:00
net nfsd-6.4 fixes: 2023-06-02 13:38:55 -04:00
rust Rust changes for v6.4 2023-04-30 11:20:22 -07:00
samples samples/bpf: Drop unnecessary fallthrough 2023-05-16 19:44:05 +02:00
scripts Locking changes in v6.4: 2023-05-05 12:56:55 -07:00
security selinux: don't use make's grouped targets feature yet 2023-06-01 13:56:13 -04:00
sound ALSA: hda/realtek: Enable headset onLenovo M70/M90 2023-05-24 14:18:59 +02:00
tools tools/virtio: Add .gitignore for ringtest 2023-06-08 15:43:08 -04:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt KVM: Fix vcpu_array[0] races 2023-05-19 13:56:26 -04:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore linux-kselftest-kunit-6.4-rc1 2023-04-24 12:31:32 -07:00
.mailmap mailmap: add entries for Nikolay Aleksandrov 2023-05-17 09:35:05 +01:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: sctp: move Neil to CREDITS 2023-05-12 08:51:32 +01:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Char/Misc driver fixes for 6.4-rc5 2023-06-04 08:32:30 -04:00
Makefile Linux 6.4-rc5 2023-06-04 14:04:27 -04:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.