This is a note to let you know that I've just added the patch titled drm/amd/display: Fix nested FPU context in dcn21_validate_bandwidth() to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-amd-display-fix-nested-fpu-context-in-dcn21_validate_bandwidth.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 15e8b95d5f7509e0b09289be8c422c459c9f0412 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Holger=20Hoffst=C3=A4tte?= <holger@xxxxxxxxxxxxxxxxxxxxxx> Date: Fri, 5 Mar 2021 12:39:21 +0100 Subject: drm/amd/display: Fix nested FPU context in dcn21_validate_bandwidth() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Holger Hoffstätte <holger@xxxxxxxxxxxxxxxxxxxxxx> commit 15e8b95d5f7509e0b09289be8c422c459c9f0412 upstream. Commit 41401ac67791 added FPU wrappers to dcn21_validate_bandwidth(), which was correct. Unfortunately a nested function alredy contained DC_FP_START()/DC_FP_END() calls, which results in nested FPU context enter/exit and complaints by kernel_fpu_begin_mask(). This can be observed e.g. with 5.10.20, which backported 41401ac67791 and now emits the following warning on boot: WARNING: CPU: 6 PID: 858 at arch/x86/kernel/fpu/core.c:129 kernel_fpu_begin_mask+0xa5/0xc0 Call Trace: dcn21_calculate_wm+0x47/0xa90 [amdgpu] dcn21_validate_bandwidth_fp+0x15d/0x2b0 [amdgpu] dcn21_validate_bandwidth+0x29/0x40 [amdgpu] dc_validate_global_state+0x3c7/0x4c0 [amdgpu] The warning is emitted due to the additional DC_FP_START/END calls in patch_bounding_box(), which is inlined into dcn21_calculate_wm(), its only caller. Removing the calls brings the code in line with dcn20 and makes the warning disappear. Fixes: 41401ac67791 ("drm/amd/display: Add FPU wrappers to dcn21_validate_bandwidth()") Signed-off-by: Holger Hoffstätte <holger@xxxxxxxxxxxxxxxxxxxxxx> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c | 4 ---- 1 file changed, 4 deletions(-) --- a/drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c +++ b/drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c @@ -1062,8 +1062,6 @@ static void patch_bounding_box(struct dc { int i; - DC_FP_START(); - if (dc->bb_overrides.sr_exit_time_ns) { for (i = 0; i < WM_SET_COUNT; i++) { dc->clk_mgr->bw_params->wm_table.entries[i].sr_exit_time_us = @@ -1088,8 +1086,6 @@ static void patch_bounding_box(struct dc dc->bb_overrides.dram_clock_change_latency_ns / 1000.0; } } - - DC_FP_END(); } void dcn21_calculate_wm( Patches currently in stable-queue which might be from holger@xxxxxxxxxxxxxxxxxxxxxx are queue-5.11/drm-amd-display-fix-nested-fpu-context-in-dcn21_validate_bandwidth.patch queue-5.11/drm-amdgpu-display-use-gfp_atomic-in-dcn21_validate_bandwidth_fp.patch