It turns out that if you happen to have a kernel config where CONFIG_DRM_PANIC is disabled and spinlock debugging is enabled, along with KMS being enabled - we'll end up trying to acquire an uninitialized spin_lock with drm_panic_lock() when we try to do a commit:
rvkms rvkms.0: [drm:drm_atomic_commit] committing 0000000068d2ade1 INFO: trying to register non-static key. The code is fine but needs lockdep annotation, or maybe you didn't initialize this object before use? turning off the locking correctness validator. CPU: 4 PID: 1347 Comm: modprobe Not tainted 6.10.0-rc1Lyude-Test+ #272 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS edk2-20240524-3.fc40 05/24/2024 Call Trace: <TASK> dump_stack_lvl+0x77/0xa0 assign_lock_key+0x114/0x120 register_lock_class+0xa8/0x2c0 __lock_acquire+0x7d/0x2bd0 ? __vmap_pages_range_noflush+0x3a8/0x550 ? drm_atomic_helper_swap_state+0x2ad/0x3a0 lock_acquire+0xec/0x290 ? drm_atomic_helper_swap_state+0x2ad/0x3a0 ? lock_release+0xee/0x310 _raw_spin_lock_irqsave+0x4e/0x70 ? drm_atomic_helper_swap_state+0x2ad/0x3a0 drm_atomic_helper_swap_state+0x2ad/0x3a0 drm_atomic_helper_commit+0xb1/0x270 drm_atomic_commit+0xaf/0xe0 ? __pfx___drm_printfn_info+0x10/0x10 drm_client_modeset_commit_atomic+0x1a1/0x250 drm_client_modeset_commit_locked+0x4b/0x180 drm_client_modeset_commit+0x27/0x50 __drm_fb_helper_restore_fbdev_mode_unlocked+0x76/0x90 drm_fb_helper_set_par+0x38/0x40 fbcon_init+0x3c4/0x690 visual_init+0xc0/0x120 do_bind_con_driver+0x409/0x4c0 do_take_over_console+0x233/0x280 do_fb_registered+0x11f/0x210 fbcon_fb_registered+0x2c/0x60 register_framebuffer+0x248/0x2a0 __drm_fb_helper_initial_config_and_unlock+0x58a/0x720 drm_fbdev_generic_client_hotplug+0x6e/0xb0 drm_client_register+0x76/0xc0 _RNvXs_CsHeezP08sTT_5rvkmsNtB4_5RvkmsNtNtCs1cdwasc6FUb_6kernel8platform6Driver5probe+0xed2/0x1060 [rvkms] ? _RNvMs_NtCs1cdwasc6FUb_6kernel8platformINtB4_7AdapterNtCsHeezP08sTT_5rvkms5RvkmsE14probe_callbackBQ_+0x2b/0x70 [rvkms] ? acpi_dev_pm_attach+0x25/0x110 ? platform_probe+0x6a/0xa0 ? really_probe+0x10b/0x400 ? __driver_probe_device+0x7c/0x140 ? driver_probe_device+0x22/0x1b0 ? __device_attach_driver+0x13a/0x1c0 ? __pfx___device_attach_driver+0x10/0x10 ? bus_for_each_drv+0x114/0x170 ? __device_attach+0xd6/0x1b0 ? bus_probe_device+0x9e/0x120 ? device_add+0x288/0x4b0 ? platform_device_add+0x75/0x230 ? platform_device_register_full+0x141/0x180 ? rust_helper_platform_device_register_simple+0x85/0xb0 ? _RNvMs2_NtCs1cdwasc6FUb_6kernel8platformNtB5_6Device13create_simple+0x1d/0x60 ? _RNvXs0_CsHeezP08sTT_5rvkmsNtB5_5RvkmsNtCs1cdwasc6FUb_6kernel6Module4init+0x11e/0x160 [rvkms] ? 0xffffffffc083f000 ? init_module+0x20/0x1000 [rvkms] ? kernfs_xattr_get+0x3e/0x80 ? do_one_initcall+0x148/0x3f0 ? __lock_acquire+0x5ef/0x2bd0 ? __lock_acquire+0x5ef/0x2bd0 ? __lock_acquire+0x5ef/0x2bd0 ? put_cpu_partial+0x51/0x1d0 ? lock_acquire+0xec/0x290 ? put_cpu_partial+0x51/0x1d0 ? lock_release+0xee/0x310 ? put_cpu_partial+0x51/0x1d0 ? fs_reclaim_acquire+0x69/0xf0 ? lock_acquire+0xec/0x290 ? fs_reclaim_acquire+0x69/0xf0 ? kfree+0x22f/0x340 ? lock_release+0xee/0x310 ? kmalloc_trace_noprof+0x48/0x340 ? do_init_module+0x22/0x240 ? kmalloc_trace_noprof+0x155/0x340 ? do_init_module+0x60/0x240 ? __se_sys_finit_module+0x2e0/0x3f0 ? do_syscall_64+0xa4/0x180 ? syscall_exit_to_user_mode+0x108/0x140 ? do_syscall_64+0xb0/0x180 ? vma_end_read+0xd0/0xe0 ? do_user_addr_fault+0x309/0x640 ? clear_bhb_loop+0x45/0xa0 ? clear_bhb_loop+0x45/0xa0 ? clear_bhb_loop+0x45/0xa0 ? entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK>
Fix this by stubbing these macros out when this config option isn't enabled, along with fixing the unused variable warning that introduces.
Signed-off-by: Lyude Paul lyude@redhat.com Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Fixes: e2a1cda3e0c7 ("drm/panic: Add drm panic locking") Cc: stable@vger.kernel.org # v6.10+
---
V2: * Use static inline instead of macros so we don't need __maybe_unused
--- drivers/gpu/drm/drm_atomic_helper.c | 2 +- include/drm/drm_panic.h | 14 ++++++++++++++ 2 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 43cdf39019a44..5186d2114a503 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -3015,7 +3015,7 @@ int drm_atomic_helper_swap_state(struct drm_atomic_state *state, bool stall) { int i, ret; - unsigned long flags; + unsigned long flags = 0; struct drm_connector *connector; struct drm_connector_state *old_conn_state, *new_conn_state; struct drm_crtc *crtc; diff --git a/include/drm/drm_panic.h b/include/drm/drm_panic.h index 54085d5d05c34..f4e1fa9ae607a 100644 --- a/include/drm/drm_panic.h +++ b/include/drm/drm_panic.h @@ -64,6 +64,8 @@ struct drm_scanout_buffer {
};
+#ifdef CONFIG_DRM_PANIC + /** * drm_panic_trylock - try to enter the panic printing critical section * @dev: struct drm_device @@ -149,4 +151,16 @@ struct drm_scanout_buffer { #define drm_panic_unlock(dev, flags) \ raw_spin_unlock_irqrestore(&(dev)->mode_config.panic_lock, flags)
+#else + +static inline bool drm_panic_trylock(struct drm_device *dev, unsigned long flags) +{ + return true; +} + +static inline void drm_panic_lock(struct drm_device *dev, unsigned long flags) {} +static inline void drm_panic_unlock(struct drm_device *dev, unsigned long flags) {} + +#endif + #endif /* __DRM_PANIC_H__ */
base-commit: bf05aeac230e390a5aee4bd3dc978b0c4d7e745f
On 17/09/2024 01:00, Lyude Paul wrote:
It turns out that if you happen to have a kernel config where CONFIG_DRM_PANIC is disabled and spinlock debugging is enabled, along with KMS being enabled - we'll end up trying to acquire an uninitialized spin_lock with drm_panic_lock() when we try to do a commit:
The raw spinlock should be initialized in drm_dev_init() [1] regardless of DRM_PANIC being enabled or not.
From the call trace, it looks like you are calling drm_client_register() before calling drm_dev_register(), and that's probably the root cause.
I didn't find a doc saying drm_dev_register() should be done before drm_client_register(), but all drivers are doing it this way.
Can you try to do that in rvkms, and see if it fixes this error ?
Best regards,
Eek - sorry, I had already pushed this since it had been reviewed a while ago and I just forgot to push it afterwards. This being said though - I'm a little confused here myself. This is correct - drm_client_register was getting called too early, I wonder if I ran into this before I had moved around the order of stuff in the KMS init stuff for rust. I will check today and if it fixes the issue, I'll look at just sending out a revert for review.
On Tue, 2024-09-17 at 09:32 +0200, Jocelyn Falempe wrote:
On 17/09/2024 01:00, Lyude Paul wrote:
It turns out that if you happen to have a kernel config where CONFIG_DRM_PANIC is disabled and spinlock debugging is enabled, along with KMS being enabled - we'll end up trying to acquire an uninitialized spin_lock with drm_panic_lock() when we try to do a commit:
The raw spinlock should be initialized in drm_dev_init() [1] regardless of DRM_PANIC being enabled or not.
From the call trace, it looks like you are calling drm_client_register() before calling drm_dev_register(), and that's probably the root cause.
I didn't find a doc saying drm_dev_register() should be done before drm_client_register(), but all drivers are doing it this way.
Can you try to do that in rvkms, and see if it fixes this error ?
Best regards,
linux-stable-mirror@lists.linaro.org
-
Jocelyn Falempe -
Lyude Paul