Re: [PATCH 1/2] Revert "drm/tidss: Annotate dma-fence critical section in commit path"
From: Aradhya Bhatia
Date: Mon Oct 02 2023 - 20:19:30 EST
On 20-Sep-23 18:27, Tomi Valkeinen wrote:
> This reverts commit 4d56a4f08391857ba93465de489707b66adad114.
>
> The DMA-fence annotations cause a lockdep warning (see below). As per
> https://patchwork.freedesktop.org/patch/462170/ it sounds like the
> annotations don't work correctly.
>
> ======================================================
> WARNING: possible circular locking dependency detected
> 6.6.0-rc2+ #1 Not tainted
> ------------------------------------------------------
> kmstest/733 is trying to acquire lock:
> ffff8000819377f0 (fs_reclaim){+.+.}-{0:0}, at: __kmem_cache_alloc_node+0x58/0x2d4
>
> but task is already holding lock:
> ffff800081a06aa0 (dma_fence_map){++++}-{0:0}, at: tidss_atomic_commit_tail+0x20/0xc0 [tidss]
>
> which lock already depends on the new lock.
>
> the existing dependency chain (in reverse order) is:
>
> -> #2 (dma_fence_map){++++}-{0:0}:
> __dma_fence_might_wait+0x5c/0xd0
> dma_resv_lockdep+0x1a4/0x32c
> do_one_initcall+0x84/0x2fc
> kernel_init_freeable+0x28c/0x4c4
> kernel_init+0x24/0x1dc
> ret_from_fork+0x10/0x20
>
> -> #1 (mmu_notifier_invalidate_range_start){+.+.}-{0:0}:
> fs_reclaim_acquire+0x70/0xe4
> __kmem_cache_alloc_node+0x58/0x2d4
> kmalloc_trace+0x38/0x78
> __kthread_create_worker+0x3c/0x150
> kthread_create_worker+0x64/0x8c
> workqueue_init+0x1e8/0x2f0
> kernel_init_freeable+0x11c/0x4c4
> kernel_init+0x24/0x1dc
> ret_from_fork+0x10/0x20
>
> -> #0 (fs_reclaim){+.+.}-{0:0}:
> __lock_acquire+0x1370/0x20d8
> lock_acquire+0x1e8/0x308
> fs_reclaim_acquire+0xd0/0xe4
> __kmem_cache_alloc_node+0x58/0x2d4
> __kmalloc_node_track_caller+0x58/0xf0
> kmemdup+0x34/0x60
> regmap_bulk_write+0x64/0x2c0
> tc358768_bridge_pre_enable+0x8c/0x12d0 [tc358768]
> drm_atomic_bridge_call_pre_enable+0x68/0x80 [drm]
> drm_atomic_bridge_chain_pre_enable+0x50/0x158 [drm]
> drm_atomic_helper_commit_modeset_enables+0x164/0x264 [drm_kms_helper]
> tidss_atomic_commit_tail+0x58/0xc0 [tidss]
> commit_tail+0xa0/0x188 [drm_kms_helper]
> drm_atomic_helper_commit+0x1a8/0x1c0 [drm_kms_helper]
> drm_atomic_commit+0xa8/0xe0 [drm]
> drm_mode_atomic_ioctl+0x9ec/0xc80 [drm]
> drm_ioctl_kernel+0xc4/0x170 [drm]
> drm_ioctl+0x234/0x4b0 [drm]
> drm_compat_ioctl+0x110/0x12c [drm]
> __arm64_compat_sys_ioctl+0x128/0x150
> invoke_syscall+0x48/0x110
> el0_svc_common.constprop.0+0x40/0xe0
> do_el0_svc_compat+0x1c/0x38
> el0_svc_compat+0x48/0xb4
> el0t_32_sync_handler+0xb0/0x138
> el0t_32_sync+0x194/0x198
>
> other info that might help us debug this:
>
> Chain exists of:
> fs_reclaim --> mmu_notifier_invalidate_range_start --> dma_fence_map
>
> Possible unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> rlock(dma_fence_map);
> lock(mmu_notifier_invalidate_range_start);
> lock(dma_fence_map);
> lock(fs_reclaim);
>
> *** DEADLOCK ***
>
> 3 locks held by kmstest/733:
> #0: ffff800082e5bba0 (crtc_ww_class_acquire){+.+.}-{0:0}, at: drm_mode_atomic_ioctl+0x118/0xc80 [drm]
> #1: ffff000004224c88 (crtc_ww_class_mutex){+.+.}-{3:3}, at: modeset_lock+0xdc/0x1a0 [drm]
> #2: ffff800081a06aa0 (dma_fence_map){++++}-{0:0}, at: tidss_atomic_commit_tail+0x20/0xc0 [tidss]
>
> stack backtrace:
> CPU: 0 PID: 733 Comm: kmstest Not tainted 6.6.0-rc2+ #1
> Hardware name: Toradex Verdin AM62 on Verdin Development Board (DT)
> Call trace:
> dump_backtrace+0x98/0x118
> show_stack+0x18/0x24
> dump_stack_lvl+0x60/0xac
> dump_stack+0x18/0x24
> print_circular_bug+0x288/0x368
> check_noncircular+0x168/0x17c
> __lock_acquire+0x1370/0x20d8
> lock_acquire+0x1e8/0x308
> fs_reclaim_acquire+0xd0/0xe4
> __kmem_cache_alloc_node+0x58/0x2d4
> __kmalloc_node_track_caller+0x58/0xf0
> kmemdup+0x34/0x60
> regmap_bulk_write+0x64/0x2c0
> tc358768_bridge_pre_enable+0x8c/0x12d0 [tc358768]
> drm_atomic_bridge_call_pre_enable+0x68/0x80 [drm]
> drm_atomic_bridge_chain_pre_enable+0x50/0x158 [drm]
> drm_atomic_helper_commit_modeset_enables+0x164/0x264 [drm_kms_helper]
> tidss_atomic_commit_tail+0x58/0xc0 [tidss]
> commit_tail+0xa0/0x188 [drm_kms_helper]
> drm_atomic_helper_commit+0x1a8/0x1c0 [drm_kms_helper]
> drm_atomic_commit+0xa8/0xe0 [drm]
> drm_mode_atomic_ioctl+0x9ec/0xc80 [drm]
> drm_ioctl_kernel+0xc4/0x170 [drm]
> drm_ioctl+0x234/0x4b0 [drm]
> drm_compat_ioctl+0x110/0x12c [drm]
> __arm64_compat_sys_ioctl+0x128/0x150
> invoke_syscall+0x48/0x110
> el0_svc_common.constprop.0+0x40/0xe0
> do_el0_svc_compat+0x1c/0x38
> el0_svc_compat+0x48/0xb4
> el0t_32_sync_handler+0xb0/0x138
> el0t_32_sync+0x194/0x198
>
> Fixes: 4d56a4f08391 ("drm/tidss: Annotate dma-fence critical section in commit path")
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Reviewed-by: Aradhya Bhatia <a-bhatia1@xxxxxx>
Regards
Aradhya
> ---
> drivers/gpu/drm/tidss/tidss_kms.c | 4 ----
> 1 file changed, 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/tidss/tidss_kms.c b/drivers/gpu/drm/tidss/tidss_kms.c
> index c979ad1af236..d096d8d2bc8f 100644
> --- a/drivers/gpu/drm/tidss/tidss_kms.c
> +++ b/drivers/gpu/drm/tidss/tidss_kms.c
> @@ -4,8 +4,6 @@
> * Author: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
> */
>
> -#include <linux/dma-fence.h>
> -
> #include <drm/drm_atomic.h>
> #include <drm/drm_atomic_helper.h>
> #include <drm/drm_bridge.h>
> @@ -25,7 +23,6 @@ static void tidss_atomic_commit_tail(struct drm_atomic_state *old_state)
> {
> struct drm_device *ddev = old_state->dev;
> struct tidss_device *tidss = to_tidss(ddev);
> - bool fence_cookie = dma_fence_begin_signalling();
>
> dev_dbg(ddev->dev, "%s\n", __func__);
>
> @@ -36,7 +33,6 @@ static void tidss_atomic_commit_tail(struct drm_atomic_state *old_state)
> drm_atomic_helper_commit_modeset_enables(ddev, old_state);
>
> drm_atomic_helper_commit_hw_done(old_state);
> - dma_fence_end_signalling(fence_cookie);
> drm_atomic_helper_wait_for_flip_done(ddev, old_state);
>
> drm_atomic_helper_cleanup_planes(ddev, old_state);
>