Re: [PATCH] rv: Fix boot failure when kernel lockdown is active
From: Gabriele Monaco <gmonaco@redhat.com>
Date: 2025-09-17 13:57:44
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On Wed, 2025-09-17 at 12:57 +0000, Xiu Jianfeng wrote:
From: Xiu Jianfeng <xiujianfeng@huawei.com> When booting kernel with lockdown=confidentiality parameter, the system will hang at rv_register_reactor() due to waiting for rv_interface_lock, as shown in the following log,
Thanks for finding this, the problem was already fixed in [1], which is on its way to getting merged. [1] - https://lore.kernel.org/all/20250903065112.1878330-1-zhen.ni@easystack.cn (local)
quoted hunk ↗ jump to hunk
INFO: task swapper/0:1 blocked for more than 122 seconds. Not tainted 6.17.0-rc6-next-20250915+ #29 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:swapper/0 state:D stack:0 pid:1 tgid:1 ppid:0 Call Trace: <TASK> __schedule+0x492/0x1600 schedule+0x27/0xf0 schedule_preempt_disabled+0x15/0x30 __mutex_lock.constprop.0+0x538/0x9e0 ? vprintk+0x18/0x50 ? _printk+0x5f/0x90 __mutex_lock_slowpath+0x13/0x20 mutex_lock+0x3b/0x50 rv_register_reactor+0x48/0xe0 ? __pfx_register_react_printk+0x10/0x10 register_react_printk+0x15/0x20 do_one_initcall+0x5d/0x340 kernel_init_freeable+0x351/0x540 ? __pfx_kernel_init+0x10/0x10 kernel_init+0x1b/0x200 ? __pfx_kernel_init+0x10/0x10 ret_from_fork+0x1fb/0x220 ? __pfx_kernel_init+0x10/0x10 ret_from_fork_asm+0x1a/0x30 The root cause is that, when the kernel lockdown is in confidentiality mode, rv_create_dir(), which is essentially tracefs_create_dir(), will return NULL. This, in turn, causes create_monitor_dir() to return -ENOMEM, and finally leading to the mutex not being unlocked. Fixes: 24cbfe18d55a ("rv: Merge struct rv_monitor_def into struct rv_monitor") Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com> --- kernel/trace/rv/rv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/kernel/trace/rv/rv.c b/kernel/trace/rv/rv.c index 1482e91c39f4..e35565dd2dc5 100644 --- a/kernel/trace/rv/rv.c +++ b/kernel/trace/rv/rv.c@@ -805,7 +805,7 @@ int rv_register_monitor(struct rv_monitor*monitor, struct rv_monitor *parent) retval = create_monitor_dir(monitor, parent); if (retval) - return retval; + goto out_unlock; /* keep children close to the parent for easier visualisation */ if (parent)