[PATCH] drm/amdgpu: Add a lock when accessing the buddy trim function

[Arunpravin Paneer Selvam]

When running YouTube videos and Steam games simultaneously,
the tester found a system hang / race condition issue with
the multi-display configuration setting. Adding a lock to
the buddy allocator's trim function would be the solution.

<log snip>
[ 7197.250436] general protection fault, probably for non-canonical address 0xdead000000000108
[ 7197.250447] RIP: 0010:__alloc_range+0x8b/0x340 [amddrm_buddy]
[ 7197.250470] Call Trace:
[ 7197.250472]  <TASK>
[ 7197.250475]  ? show_regs+0x6d/0x80
[ 7197.250481]  ? die_addr+0x37/0xa0
[ 7197.250483]  ? exc_general_protection+0x1db/0x480
[ 7197.250488]  ? drm_suballoc_new+0x13c/0x93d [drm_suballoc_helper]
[ 7197.250493]  ? asm_exc_general_protection+0x27/0x30
[ 7197.250498]  ? __alloc_range+0x8b/0x340 [amddrm_buddy]
[ 7197.250501]  ? __alloc_range+0x109/0x340 [amddrm_buddy]
[ 7197.250506]  amddrm_buddy_block_trim+0x1b5/0x260 [amddrm_buddy]
[ 7197.250511]  amdgpu_vram_mgr_new+0x4f5/0x590 [amdgpu]
[ 7197.250682]  amdttm_resource_alloc+0x46/0xb0 [amdttm]
[ 7197.250689]  ttm_bo_alloc_resource+0xe4/0x370 [amdttm]
[ 7197.250696]  amdttm_bo_validate+0x9d/0x180 [amdttm]
[ 7197.250701]  amdgpu_bo_pin+0x15a/0x2f0 [amdgpu]
[ 7197.250831]  amdgpu_dm_plane_helper_prepare_fb+0xb2/0x360 [amdgpu]
[ 7197.251025]  ? try_wait_for_completion+0x59/0x70
[ 7197.251030]  drm_atomic_helper_prepare_planes.part.0+0x2f/0x1e0
[ 7197.251035]  drm_atomic_helper_prepare_planes+0x5d/0x70
[ 7197.251037]  drm_atomic_helper_commit+0x84/0x160
[ 7197.251040]  drm_atomic_nonblocking_commit+0x59/0x70
[ 7197.251043]  drm_mode_atomic_ioctl+0x720/0x850
[ 7197.251047]  ? __pfx_drm_mode_atomic_ioctl+0x10/0x10
[ 7197.251049]  drm_ioctl_kernel+0xb9/0x120
[ 7197.251053]  ? srso_alias_return_thunk+0x5/0xfbef5
[ 7197.251056]  drm_ioctl+0x2d4/0x550
[ 7197.251058]  ? __pfx_drm_mode_atomic_ioctl+0x10/0x10
[ 7197.251063]  amdgpu_drm_ioctl+0x4e/0x90 [amdgpu]
[ 7197.251186]  __x64_sys_ioctl+0xa0/0xf0
[ 7197.251190]  x64_sys_call+0x143b/0x25c0
[ 7197.251193]  do_syscall_64+0x7f/0x180
[ 7197.251197]  ? srso_alias_return_thunk+0x5/0xfbef5
[ 7197.251199]  ? amdgpu_display_user_framebuffer_create+0x215/0x320 [amdgpu]
[ 7197.251329]  ? drm_internal_framebuffer_create+0xb7/0x1a0
[ 7197.251332]  ? srso_alias_return_thunk+0x5/0xfbef5

Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>
Fixes: 4a5ad08f5377 ("drm/amdgpu: Add address alignment support to DCC buffers")
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
index 7d26a962f811..ff5e52025266 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
@@ -567,7 +567,6 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
 		else
 			remaining_size -= size;
 	}
-	mutex_unlock(&mgr->lock);
 
 	if (bo->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS && adjust_dcc_size) {
 		struct drm_buddy_block *dcc_block;
@@ -584,6 +583,7 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
 				     (u64)vres->base.size,
 				     &vres->blocks);
 	}
+	mutex_unlock(&mgr->lock);
 
 	vres->base.start = 0;
 	size = max_t(u64, amdgpu_vram_mgr_blocks_size(&vres->blocks),
-- 
2.25.1