** Tags added: kernel-daily-bug
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https://bugs.launchpad.net/bugs/2039869
Title:
Devlink reload hangs: fix race and lock issue
Status in linux-bluefield package in Ubuntu:
Invalid
Status in linux-bluefield source package in Jammy:
Fix Committed
Bug description:
Summary:
Machine hangs when doing devlink reload
How to reproduce:
Host:
[root@bu-lab24v ~]# echo '2' > /sys/class/net/ens2f0np0/device/sriov_numvfs
Arm:
root@bu-lab24v-oob:~# uname -r
5.15.0-1027-bluefield
root@bu-lab24v-oob:~# devlink dev eswitch set pci/0000:03:00.0 mode switchdev
root@bu-lab24v-oob:~# devlink dev reload pci/0000:03:00.0
*Hangs*
Arm dmesg:
[ 1089.747409] INFO: task devlink:8753 blocked for more than 120 seconds.
[ 1089.760560] Tainted: G OE 5.15.0-1027-bluefield
#29-Ubuntu
[ 1089.775086] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables
this message.
[ 1089.790829] task:devlink state:D stack: 0 pid: 8753 ppid: 5090
flags:0x00000004
[ 1089.790838] Call trace:
[ 1089.790840] __switch_to+0xf8/0x150
[ 1089.790857] __schedule+0x2b8/0x790
[ 1089.790865] schedule+0x64/0x140
[ 1089.790870] schedule_preempt_disabled+0x18/0x24
[ 1089.790874] __mutex_lock.constprop.0+0x1a0/0x680
[ 1089.790878] __mutex_lock_slowpath+0x40/0x90
[ 1089.790883] mutex_lock+0x64/0x70
[ 1089.790887] devl_lock+0x1c/0x30
[ 1089.790893] mlx5_detach_device+0x58/0x190 [mlx5_core]
[ 1089.791055] mlx5_unload_one+0x40/0xe4 [mlx5_core]
[ 1089.791177] mlx5_devlink_reload_down+0x184/0x270 [mlx5_core]
[ 1089.791318] devlink_reload+0x214/0x290
Fixes:
Checking the OFED source code, we found this missing devl trap group
also need to be backported to avoid deadlock.
void mlx5_detach_device(struct mlx5_core_dev *dev, bool suspend)
{
...
#ifdef HAVE_DEVL_PORT_REGISTER
#ifdef HAVE_DEVL_TRAP_GROUPS_REGISTER
devl_assert_locked(priv_to_devlink(dev));
#else
devl_lock(devlink);
#endif /* HAVE_DEVL_TRAP_GROUPS_REGISTER */
#endif /* HAVE_DEVL_PORT_REGISTER */
mutex_lock(&mlx5_intf_mutex);
#ifdef HAVE_DEVL_PORT_REGISTER
Related issue:
#2032378 Devlink backport: fix race and lock issue
So cherry-pick the patch below
commit 852e85a704c2e11c050bdea286bc438aba4f4a22
Author: Jiri Pirko <[email protected]>
Date: Sat Jul 16 13:02:34 2022 +0200
net: devlink: add unlocked variants of devling_trap*() functions
Add unlocked variants of devl_trap*() functions to be used in drivers
called-in with devlink->lock held.
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