June 2025 - Linux-stable-mirror

Re: [PATCH v4] virtio_blk: Fix disk deletion hang on device surprise removal

by ALOK TIWARI

On 31-05-2025 11:03, Parav Pandit wrote: > + if (!virtqueue_is_broken(vblk->vqs[0].vq)) is it call, if the virtqueue is not broken ? > + virtblk_cleanup_broken_device(vblk); > + > del_gendisk(vblk->disk); > blk_mq_free_tag_set(&vblk->tag_set); Thanks, Alok

4 weeks

2
1
0 0

[PATCH AUTOSEL 5.4 01/22] drm/amdgpu/gfx6: fix CSIB handling

by Sasha Levin

From: Alex Deucher <alexander.deucher(a)amd.com> [ Upstream commit 8307ebc15c1ea98a8a0b7837af1faa6c01514577 ] We shouldn't return after the last section. We need to update the rest of the CSIB. Reviewed-by: Rodrigo Siqueira <siqueira(a)igalia.com> Signed-off-by: Alex Deucher <alexander.deucher(a)amd.com> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- Now let me understand what the bug is. Looking at the original code: ```c for (sect = adev->gfx.rlc.cs_data; sect->section != NULL; ++sect) { for (ext = sect->section; ext->extent != NULL; ++ext) { if (sect->id == SECT_CONTEXT) { // process SECT_CONTEXT sections } else { return; // BUG: This returns early, skipping remaining code } } } // Important code that should always run: buffer[count++] = cpu_to_le32(PACKET3(PACKET3_SET_CONTEXT_REG, 1)); buffer[count++] = cpu_to_le32(mmPA_SC_RASTER_CONFIG - PACKET3_SET_CONTEXT_REG_START); // ... more important buffer initialization ``` The fix removes the early return so that all sections are processed and the important buffer initialization at the end always runs. **YES** This commit should be backported to stable kernel trees for the following reasons: 1. **Clear Bug Fix**: The commit fixes a clear logic error where an early return statement prevents critical buffer initialization code from executing. The original code would return immediately when encountering a non- SECT_CONTEXT section, skipping the important packet commands that should always be written to the buffer (PACKET3_SET_CONTEXT_REG, PACKET3_PREAMBLE_END_CLEAR_STATE, PACKET3_CLEAR_STATE). 2. **Functional Impact**: This bug affects the Clear State Indirect Buffer (CSIB) handling in AMD GPU driver for GFX6 hardware. The incomplete buffer initialization could lead to: - Incorrect GPU state during graphics operations - Potential rendering issues or GPU hangs - Inconsistent hardware behavior 3. **Small and Contained Fix**: The fix is minimal - it simply removes two lines (the else block with return statement). This is a low-risk change that doesn't introduce new functionality or alter the architecture. 4. **Hardware-Specific Bug**: This affects real users with GFX6 AMD GPUs. The bug prevents proper initialization of the GPU's clear state buffer, which is essential for correct GPU operation. 5. **Similar to Historical Backports**: Looking at commit 4 in the similar commits (marked as YES for backporting), which also fixed preamble handling issues in the AMD GPU driver, this follows a similar pattern of fixing command buffer handling bugs. The commit message clearly indicates this is a bug fix ("We shouldn't return after the last section. We need to update the rest of the CSIB"), and the code change confirms that critical buffer initialization was being skipped due to the premature return. drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c index 7f0a63628c43a..eac329fe27902 100644 --- a/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c @@ -2901,8 +2901,6 @@ static void gfx_v6_0_get_csb_buffer(struct amdgpu_device *adev, buffer[count++] = cpu_to_le32(ext->reg_index - 0xa000); for (i = 0; i < ext->reg_count; i++) buffer[count++] = cpu_to_le32(ext->extent[i]); - } else { - return; } } } -- 2.39.5

4 weeks

1
21
0 0

[PATCH AUTOSEL 5.10 01/34] drm/amdgpu/gfx6: fix CSIB handling

by Sasha Levin

From: Alex Deucher <alexander.deucher(a)amd.com> [ Upstream commit 8307ebc15c1ea98a8a0b7837af1faa6c01514577 ] We shouldn't return after the last section. We need to update the rest of the CSIB. Reviewed-by: Rodrigo Siqueira <siqueira(a)igalia.com> Signed-off-by: Alex Deucher <alexander.deucher(a)amd.com> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- Now let me understand what the bug is. Looking at the original code: ```c for (sect = adev->gfx.rlc.cs_data; sect->section != NULL; ++sect) { for (ext = sect->section; ext->extent != NULL; ++ext) { if (sect->id == SECT_CONTEXT) { // process SECT_CONTEXT sections } else { return; // BUG: This returns early, skipping remaining code } } } // Important code that should always run: buffer[count++] = cpu_to_le32(PACKET3(PACKET3_SET_CONTEXT_REG, 1)); buffer[count++] = cpu_to_le32(mmPA_SC_RASTER_CONFIG - PACKET3_SET_CONTEXT_REG_START); // ... more important buffer initialization ``` The fix removes the early return so that all sections are processed and the important buffer initialization at the end always runs. **YES** This commit should be backported to stable kernel trees for the following reasons: 1. **Clear Bug Fix**: The commit fixes a clear logic error where an early return statement prevents critical buffer initialization code from executing. The original code would return immediately when encountering a non- SECT_CONTEXT section, skipping the important packet commands that should always be written to the buffer (PACKET3_SET_CONTEXT_REG, PACKET3_PREAMBLE_END_CLEAR_STATE, PACKET3_CLEAR_STATE). 2. **Functional Impact**: This bug affects the Clear State Indirect Buffer (CSIB) handling in AMD GPU driver for GFX6 hardware. The incomplete buffer initialization could lead to: - Incorrect GPU state during graphics operations - Potential rendering issues or GPU hangs - Inconsistent hardware behavior 3. **Small and Contained Fix**: The fix is minimal - it simply removes two lines (the else block with return statement). This is a low-risk change that doesn't introduce new functionality or alter the architecture. 4. **Hardware-Specific Bug**: This affects real users with GFX6 AMD GPUs. The bug prevents proper initialization of the GPU's clear state buffer, which is essential for correct GPU operation. 5. **Similar to Historical Backports**: Looking at commit 4 in the similar commits (marked as YES for backporting), which also fixed preamble handling issues in the AMD GPU driver, this follows a similar pattern of fixing command buffer handling bugs. The commit message clearly indicates this is a bug fix ("We shouldn't return after the last section. We need to update the rest of the CSIB"), and the code change confirms that critical buffer initialization was being skipped due to the premature return. drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c index 79c52c7a02e3a..d447b2416b98b 100644 --- a/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c @@ -2896,8 +2896,6 @@ static void gfx_v6_0_get_csb_buffer(struct amdgpu_device *adev, buffer[count++] = cpu_to_le32(ext->reg_index - 0xa000); for (i = 0; i < ext->reg_count; i++) buffer[count++] = cpu_to_le32(ext->extent[i]); - } else { - return; } } } -- 2.39.5

4 weeks

1
33
0 0

[PATCH AUTOSEL 5.15 01/43] drm/amdgpu/gfx6: fix CSIB handling

by Sasha Levin

From: Alex Deucher <alexander.deucher(a)amd.com> [ Upstream commit 8307ebc15c1ea98a8a0b7837af1faa6c01514577 ] We shouldn't return after the last section. We need to update the rest of the CSIB. Reviewed-by: Rodrigo Siqueira <siqueira(a)igalia.com> Signed-off-by: Alex Deucher <alexander.deucher(a)amd.com> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- Now let me understand what the bug is. Looking at the original code: ```c for (sect = adev->gfx.rlc.cs_data; sect->section != NULL; ++sect) { for (ext = sect->section; ext->extent != NULL; ++ext) { if (sect->id == SECT_CONTEXT) { // process SECT_CONTEXT sections } else { return; // BUG: This returns early, skipping remaining code } } } // Important code that should always run: buffer[count++] = cpu_to_le32(PACKET3(PACKET3_SET_CONTEXT_REG, 1)); buffer[count++] = cpu_to_le32(mmPA_SC_RASTER_CONFIG - PACKET3_SET_CONTEXT_REG_START); // ... more important buffer initialization ``` The fix removes the early return so that all sections are processed and the important buffer initialization at the end always runs. **YES** This commit should be backported to stable kernel trees for the following reasons: 1. **Clear Bug Fix**: The commit fixes a clear logic error where an early return statement prevents critical buffer initialization code from executing. The original code would return immediately when encountering a non- SECT_CONTEXT section, skipping the important packet commands that should always be written to the buffer (PACKET3_SET_CONTEXT_REG, PACKET3_PREAMBLE_END_CLEAR_STATE, PACKET3_CLEAR_STATE). 2. **Functional Impact**: This bug affects the Clear State Indirect Buffer (CSIB) handling in AMD GPU driver for GFX6 hardware. The incomplete buffer initialization could lead to: - Incorrect GPU state during graphics operations - Potential rendering issues or GPU hangs - Inconsistent hardware behavior 3. **Small and Contained Fix**: The fix is minimal - it simply removes two lines (the else block with return statement). This is a low-risk change that doesn't introduce new functionality or alter the architecture. 4. **Hardware-Specific Bug**: This affects real users with GFX6 AMD GPUs. The bug prevents proper initialization of the GPU's clear state buffer, which is essential for correct GPU operation. 5. **Similar to Historical Backports**: Looking at commit 4 in the similar commits (marked as YES for backporting), which also fixed preamble handling issues in the AMD GPU driver, this follows a similar pattern of fixing command buffer handling bugs. The commit message clearly indicates this is a bug fix ("We shouldn't return after the last section. We need to update the rest of the CSIB"), and the code change confirms that critical buffer initialization was being skipped due to the premature return. drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c index 6a8dadea40f92..79074d22959b9 100644 --- a/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c @@ -2897,8 +2897,6 @@ static void gfx_v6_0_get_csb_buffer(struct amdgpu_device *adev, buffer[count++] = cpu_to_le32(ext->reg_index - 0xa000); for (i = 0; i < ext->reg_count; i++) buffer[count++] = cpu_to_le32(ext->extent[i]); - } else { - return; } } } -- 2.39.5

4 weeks

1
42
0 0

[PATCH AUTOSEL 6.1 01/58] drm/amdgpu/gfx6: fix CSIB handling

by Sasha Levin

From: Alex Deucher <alexander.deucher(a)amd.com> [ Upstream commit 8307ebc15c1ea98a8a0b7837af1faa6c01514577 ] We shouldn't return after the last section. We need to update the rest of the CSIB. Reviewed-by: Rodrigo Siqueira <siqueira(a)igalia.com> Signed-off-by: Alex Deucher <alexander.deucher(a)amd.com> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- Now let me understand what the bug is. Looking at the original code: ```c for (sect = adev->gfx.rlc.cs_data; sect->section != NULL; ++sect) { for (ext = sect->section; ext->extent != NULL; ++ext) { if (sect->id == SECT_CONTEXT) { // process SECT_CONTEXT sections } else { return; // BUG: This returns early, skipping remaining code } } } // Important code that should always run: buffer[count++] = cpu_to_le32(PACKET3(PACKET3_SET_CONTEXT_REG, 1)); buffer[count++] = cpu_to_le32(mmPA_SC_RASTER_CONFIG - PACKET3_SET_CONTEXT_REG_START); // ... more important buffer initialization ``` The fix removes the early return so that all sections are processed and the important buffer initialization at the end always runs. **YES** This commit should be backported to stable kernel trees for the following reasons: 1. **Clear Bug Fix**: The commit fixes a clear logic error where an early return statement prevents critical buffer initialization code from executing. The original code would return immediately when encountering a non- SECT_CONTEXT section, skipping the important packet commands that should always be written to the buffer (PACKET3_SET_CONTEXT_REG, PACKET3_PREAMBLE_END_CLEAR_STATE, PACKET3_CLEAR_STATE). 2. **Functional Impact**: This bug affects the Clear State Indirect Buffer (CSIB) handling in AMD GPU driver for GFX6 hardware. The incomplete buffer initialization could lead to: - Incorrect GPU state during graphics operations - Potential rendering issues or GPU hangs - Inconsistent hardware behavior 3. **Small and Contained Fix**: The fix is minimal - it simply removes two lines (the else block with return statement). This is a low-risk change that doesn't introduce new functionality or alter the architecture. 4. **Hardware-Specific Bug**: This affects real users with GFX6 AMD GPUs. The bug prevents proper initialization of the GPU's clear state buffer, which is essential for correct GPU operation. 5. **Similar to Historical Backports**: Looking at commit 4 in the similar commits (marked as YES for backporting), which also fixed preamble handling issues in the AMD GPU driver, this follows a similar pattern of fixing command buffer handling bugs. The commit message clearly indicates this is a bug fix ("We shouldn't return after the last section. We need to update the rest of the CSIB"), and the code change confirms that critical buffer initialization was being skipped due to the premature return. drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c index 204b246f0e3f9..0219f1175c078 100644 --- a/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c @@ -2873,8 +2873,6 @@ static void gfx_v6_0_get_csb_buffer(struct amdgpu_device *adev, buffer[count++] = cpu_to_le32(ext->reg_index - 0xa000); for (i = 0; i < ext->reg_count; i++) buffer[count++] = cpu_to_le32(ext->extent[i]); - } else { - return; } } } -- 2.39.5

4 weeks

1
57
0 0

[PATCH AUTOSEL 6.6 01/66] drm/amdgpu/gfx6: fix CSIB handling

by Sasha Levin

From: Alex Deucher <alexander.deucher(a)amd.com> [ Upstream commit 8307ebc15c1ea98a8a0b7837af1faa6c01514577 ] We shouldn't return after the last section. We need to update the rest of the CSIB. Reviewed-by: Rodrigo Siqueira <siqueira(a)igalia.com> Signed-off-by: Alex Deucher <alexander.deucher(a)amd.com> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- Now let me understand what the bug is. Looking at the original code: ```c for (sect = adev->gfx.rlc.cs_data; sect->section != NULL; ++sect) { for (ext = sect->section; ext->extent != NULL; ++ext) { if (sect->id == SECT_CONTEXT) { // process SECT_CONTEXT sections } else { return; // BUG: This returns early, skipping remaining code } } } // Important code that should always run: buffer[count++] = cpu_to_le32(PACKET3(PACKET3_SET_CONTEXT_REG, 1)); buffer[count++] = cpu_to_le32(mmPA_SC_RASTER_CONFIG - PACKET3_SET_CONTEXT_REG_START); // ... more important buffer initialization ``` The fix removes the early return so that all sections are processed and the important buffer initialization at the end always runs. **YES** This commit should be backported to stable kernel trees for the following reasons: 1. **Clear Bug Fix**: The commit fixes a clear logic error where an early return statement prevents critical buffer initialization code from executing. The original code would return immediately when encountering a non- SECT_CONTEXT section, skipping the important packet commands that should always be written to the buffer (PACKET3_SET_CONTEXT_REG, PACKET3_PREAMBLE_END_CLEAR_STATE, PACKET3_CLEAR_STATE). 2. **Functional Impact**: This bug affects the Clear State Indirect Buffer (CSIB) handling in AMD GPU driver for GFX6 hardware. The incomplete buffer initialization could lead to: - Incorrect GPU state during graphics operations - Potential rendering issues or GPU hangs - Inconsistent hardware behavior 3. **Small and Contained Fix**: The fix is minimal - it simply removes two lines (the else block with return statement). This is a low-risk change that doesn't introduce new functionality or alter the architecture. 4. **Hardware-Specific Bug**: This affects real users with GFX6 AMD GPUs. The bug prevents proper initialization of the GPU's clear state buffer, which is essential for correct GPU operation. 5. **Similar to Historical Backports**: Looking at commit 4 in the similar commits (marked as YES for backporting), which also fixed preamble handling issues in the AMD GPU driver, this follows a similar pattern of fixing command buffer handling bugs. The commit message clearly indicates this is a bug fix ("We shouldn't return after the last section. We need to update the rest of the CSIB"), and the code change confirms that critical buffer initialization was being skipped due to the premature return. drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c index 34f9211b26793..80316297374cc 100644 --- a/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c @@ -2860,8 +2860,6 @@ static void gfx_v6_0_get_csb_buffer(struct amdgpu_device *adev, buffer[count++] = cpu_to_le32(ext->reg_index - 0xa000); for (i = 0; i < ext->reg_count; i++) buffer[count++] = cpu_to_le32(ext->extent[i]); - } else { - return; } } } -- 2.39.5

4 weeks

1
65
0 0

[PATCH AUTOSEL 6.12 01/93] drm/amd/display: disable DPP RCG before DPP CLK enable

by Sasha Levin

From: Charlene Liu <Charlene.Liu(a)amd.com> [ Upstream commit 1bcd679209420305a86833bc357d50021909edaf ] [why] DPP CLK enable needs to disable DPPCLK RCG first. The DPPCLK_en in dccg should always be enabled when the corresponding pipe is enabled. Reviewed-by: Hansen Dsouza <hansen.dsouza(a)amd.com> Signed-off-by: Charlene Liu <Charlene.Liu(a)amd.com> Signed-off-by: Ray Wu <ray.wu(a)amd.com> Tested-by: Daniel Wheeler <daniel.wheeler(a)amd.com> Signed-off-by: Alex Deucher <alexander.deucher(a)amd.com> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- Based on my analysis of both the commit message and code changes, my answer is: **YES** This commit should be backported to stable kernel trees for the following reasons: ## Critical Hardware Sequencing Fix The commit addresses a fundamental hardware sequencing requirement where DPP (Display Pipes and Planes) Root Clock Gating (RCG) must be disabled before enabling the DPP clock. This is a critical timing constraint that, if violated, can cause severe system issues. ## Specific Code Evidence 1. **In `dccg35_update_dpp_dto()`**, the fix adds a crucial sequencing step: ```c + dccg35_set_dppclk_rcg(dccg, dpp_inst, false); REG_SET_2(DPPCLK_DTO_PARAM[dpp_inst], 0, DPPCLK0_DTO_PHASE, phase, DPPCLK0_DTO_MODULO, modulo); dcn35_set_dppclk_enable(dccg, dpp_inst, true); ``` This ensures RCG is disabled (false) before enabling the DPP clock. 2. **In `dcn35_enable_plane()`**, explicit clock control is added: ```c + /*make sure DPPCLK is on*/ + dccg->funcs->dccg_root_gate_disable_control(dccg, dpp->inst, true); + dpp->funcs->dpp_dppclk_control(dpp, false, true); ``` 3. **Removal of problematic init code** in `dcn35_init_hw()`: ```c - if (res_pool->dccg->funcs->dccg_root_gate_disable_control) { - for (i = 0; i < res_pool->pipe_count; i++) - res_pool->dccg->funcs->dccg_root_gate_disable_control(res_pool->dccg, i, 0); - } ``` ## Similarity to Previous Critical Fixes This commit follows the pattern of Similar Commit #1, which also addressed clock gating sequencing issues that could cause system hangs. The commit message explicitly states this is needed because "DPP CLK enable needs to disable DPPCLK RCG first." ## Impact and Risk Assessment - **Bug Fixed**: Incorrect clock sequencing that can cause system instability - **Scope**: Limited to DCN35 display hardware (recent AMD GPUs) - **Complexity**: Small, focused changes with clear purpose - **Risk**: Low risk of regression - adds proper sequencing without major architectural changes This fix meets all criteria for stable backporting: - Fixes a real bug affecting users (system stability) - Small and contained changes - No new features or architectural changes - Addresses hardware constraints that cannot be worked around The commit should be backported to all stable kernels that include DCN35 display support to ensure proper display functionality and system stability for users with affected AMD GPUs. .../amd/display/dc/dccg/dcn35/dcn35_dccg.c | 38 ++++++++++++------- .../amd/display/dc/hwss/dcn35/dcn35_hwseq.c | 21 ++++++---- 2 files changed, 38 insertions(+), 21 deletions(-) diff --git a/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c b/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c index b363f5360818d..ad910065f463f 100644 --- a/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c +++ b/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c @@ -391,6 +391,7 @@ static void dccg35_set_dppclk_rcg(struct dccg *dccg, struct dcn_dccg *dccg_dcn = TO_DCN_DCCG(dccg); + if (!dccg->ctx->dc->debug.root_clock_optimization.bits.dpp && enable) return; @@ -411,6 +412,8 @@ static void dccg35_set_dppclk_rcg(struct dccg *dccg, BREAK_TO_DEBUGGER(); break; } + //DC_LOG_DEBUG("%s: inst(%d) DPPCLK rcg_disable: %d\n", __func__, inst, enable ? 0 : 1); + } static void dccg35_set_dpstreamclk_rcg( @@ -1112,30 +1115,24 @@ static void dcn35_set_dppclk_enable(struct dccg *dccg, { struct dcn_dccg *dccg_dcn = TO_DCN_DCCG(dccg); + switch (dpp_inst) { case 0: REG_UPDATE(DPPCLK_CTRL, DPPCLK0_EN, enable); - if (dccg->ctx->dc->debug.root_clock_optimization.bits.dpp) - REG_UPDATE(DCCG_GATE_DISABLE_CNTL6, DPPCLK0_ROOT_GATE_DISABLE, enable); break; case 1: REG_UPDATE(DPPCLK_CTRL, DPPCLK1_EN, enable); - if (dccg->ctx->dc->debug.root_clock_optimization.bits.dpp) - REG_UPDATE(DCCG_GATE_DISABLE_CNTL6, DPPCLK1_ROOT_GATE_DISABLE, enable); break; case 2: REG_UPDATE(DPPCLK_CTRL, DPPCLK2_EN, enable); - if (dccg->ctx->dc->debug.root_clock_optimization.bits.dpp) - REG_UPDATE(DCCG_GATE_DISABLE_CNTL6, DPPCLK2_ROOT_GATE_DISABLE, enable); break; case 3: REG_UPDATE(DPPCLK_CTRL, DPPCLK3_EN, enable); - if (dccg->ctx->dc->debug.root_clock_optimization.bits.dpp) - REG_UPDATE(DCCG_GATE_DISABLE_CNTL6, DPPCLK3_ROOT_GATE_DISABLE, enable); break; default: break; } + //DC_LOG_DEBUG("%s: dpp_inst(%d) DPPCLK_EN = %d\n", __func__, dpp_inst, enable); } @@ -1163,14 +1160,18 @@ static void dccg35_update_dpp_dto(struct dccg *dccg, int dpp_inst, ASSERT(false); phase = 0xff; } + dccg35_set_dppclk_rcg(dccg, dpp_inst, false); REG_SET_2(DPPCLK_DTO_PARAM[dpp_inst], 0, DPPCLK0_DTO_PHASE, phase, DPPCLK0_DTO_MODULO, modulo); dcn35_set_dppclk_enable(dccg, dpp_inst, true); - } else + } else { dcn35_set_dppclk_enable(dccg, dpp_inst, false); + /*we have this in hwss: disable_plane*/ + //dccg35_set_dppclk_rcg(dccg, dpp_inst, true); + } dccg->pipe_dppclk_khz[dpp_inst] = req_dppclk; } @@ -1182,6 +1183,7 @@ static void dccg35_set_dppclk_root_clock_gating(struct dccg *dccg, if (!dccg->ctx->dc->debug.root_clock_optimization.bits.dpp) return; + switch (dpp_inst) { case 0: REG_UPDATE(DCCG_GATE_DISABLE_CNTL6, DPPCLK0_ROOT_GATE_DISABLE, enable); @@ -1198,6 +1200,8 @@ static void dccg35_set_dppclk_root_clock_gating(struct dccg *dccg, default: break; } + //DC_LOG_DEBUG("%s: dpp_inst(%d) rcg: %d\n", __func__, dpp_inst, enable); + } static void dccg35_get_pixel_rate_div( @@ -1521,28 +1525,30 @@ static void dccg35_set_physymclk_root_clock_gating( switch (phy_inst) { case 0: REG_UPDATE(DCCG_GATE_DISABLE_CNTL2, - PHYASYMCLK_ROOT_GATE_DISABLE, enable ? 1 : 0); + PHYASYMCLK_ROOT_GATE_DISABLE, enable ? 0 : 1); break; case 1: REG_UPDATE(DCCG_GATE_DISABLE_CNTL2, - PHYBSYMCLK_ROOT_GATE_DISABLE, enable ? 1 : 0); + PHYBSYMCLK_ROOT_GATE_DISABLE, enable ? 0 : 1); break; case 2: REG_UPDATE(DCCG_GATE_DISABLE_CNTL2, - PHYCSYMCLK_ROOT_GATE_DISABLE, enable ? 1 : 0); + PHYCSYMCLK_ROOT_GATE_DISABLE, enable ? 0 : 1); break; case 3: REG_UPDATE(DCCG_GATE_DISABLE_CNTL2, - PHYDSYMCLK_ROOT_GATE_DISABLE, enable ? 1 : 0); + PHYDSYMCLK_ROOT_GATE_DISABLE, enable ? 0 : 1); break; case 4: REG_UPDATE(DCCG_GATE_DISABLE_CNTL2, - PHYESYMCLK_ROOT_GATE_DISABLE, enable ? 1 : 0); + PHYESYMCLK_ROOT_GATE_DISABLE, enable ? 0 : 1); break; default: BREAK_TO_DEBUGGER(); return; } + //DC_LOG_DEBUG("%s: dpp_inst(%d) PHYESYMCLK_ROOT_GATE_DISABLE:\n", __func__, phy_inst, enable ? 0 : 1); + } static void dccg35_set_physymclk( @@ -1643,6 +1649,8 @@ static void dccg35_dpp_root_clock_control( return; if (clock_on) { + dccg35_set_dppclk_rcg(dccg, dpp_inst, false); + /* turn off the DTO and leave phase/modulo at max */ dcn35_set_dppclk_enable(dccg, dpp_inst, 1); REG_SET_2(DPPCLK_DTO_PARAM[dpp_inst], 0, @@ -1654,6 +1662,8 @@ static void dccg35_dpp_root_clock_control( REG_SET_2(DPPCLK_DTO_PARAM[dpp_inst], 0, DPPCLK0_DTO_PHASE, 0, DPPCLK0_DTO_MODULO, 1); + /*we have this in hwss: disable_plane*/ + //dccg35_set_dppclk_rcg(dccg, dpp_inst, true); } dccg->dpp_clock_gated[dpp_inst] = !clock_on; diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c index ca446e08f6a27..ff247689dd6d5 100644 --- a/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c +++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c @@ -241,11 +241,6 @@ void dcn35_init_hw(struct dc *dc) dc->res_pool->hubbub->funcs->allow_self_refresh_control(dc->res_pool->hubbub, !dc->res_pool->hubbub->ctx->dc->debug.disable_stutter); } - if (res_pool->dccg->funcs->dccg_root_gate_disable_control) { - for (i = 0; i < res_pool->pipe_count; i++) - res_pool->dccg->funcs->dccg_root_gate_disable_control(res_pool->dccg, i, 0); - } - for (i = 0; i < res_pool->audio_count; i++) { struct audio *audio = res_pool->audios[i]; @@ -885,12 +880,18 @@ void dcn35_init_pipes(struct dc *dc, struct dc_state *context) void dcn35_enable_plane(struct dc *dc, struct pipe_ctx *pipe_ctx, struct dc_state *context) { + struct dpp *dpp = pipe_ctx->plane_res.dpp; + struct dccg *dccg = dc->res_pool->dccg; + + /* enable DCFCLK current DCHUB */ pipe_ctx->plane_res.hubp->funcs->hubp_clk_cntl(pipe_ctx->plane_res.hubp, true); /* initialize HUBP on power up */ pipe_ctx->plane_res.hubp->funcs->hubp_init(pipe_ctx->plane_res.hubp); - + /*make sure DPPCLK is on*/ + dccg->funcs->dccg_root_gate_disable_control(dccg, dpp->inst, true); + dpp->funcs->dpp_dppclk_control(dpp, false, true); /* make sure OPP_PIPE_CLOCK_EN = 1 */ pipe_ctx->stream_res.opp->funcs->opp_pipe_clock_control( pipe_ctx->stream_res.opp, @@ -907,6 +908,7 @@ void dcn35_enable_plane(struct dc *dc, struct pipe_ctx *pipe_ctx, // Program system aperture settings pipe_ctx->plane_res.hubp->funcs->hubp_set_vm_system_aperture_settings(pipe_ctx->plane_res.hubp, &apt); } + //DC_LOG_DEBUG("%s: dpp_inst(%d) =\n", __func__, dpp->inst); if (!pipe_ctx->top_pipe && pipe_ctx->plane_state @@ -922,6 +924,8 @@ void dcn35_plane_atomic_disable(struct dc *dc, struct pipe_ctx *pipe_ctx) { struct hubp *hubp = pipe_ctx->plane_res.hubp; struct dpp *dpp = pipe_ctx->plane_res.dpp; + struct dccg *dccg = dc->res_pool->dccg; + dc->hwss.wait_for_mpcc_disconnect(dc, dc->res_pool, pipe_ctx); @@ -939,7 +943,8 @@ void dcn35_plane_atomic_disable(struct dc *dc, struct pipe_ctx *pipe_ctx) hubp->funcs->hubp_clk_cntl(hubp, false); dpp->funcs->dpp_dppclk_control(dpp, false, false); -/*to do, need to support both case*/ + dccg->funcs->dccg_root_gate_disable_control(dccg, dpp->inst, false); + hubp->power_gated = true; hubp->funcs->hubp_reset(hubp); @@ -951,6 +956,8 @@ void dcn35_plane_atomic_disable(struct dc *dc, struct pipe_ctx *pipe_ctx) pipe_ctx->top_pipe = NULL; pipe_ctx->bottom_pipe = NULL; pipe_ctx->plane_state = NULL; + //DC_LOG_DEBUG("%s: dpp_inst(%d)=\n", __func__, dpp->inst); + } void dcn35_disable_plane(struct dc *dc, struct dc_state *state, struct pipe_ctx *pipe_ctx) -- 2.39.5

4 weeks

1
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[PATCH AUTOSEL 6.14 001/102] drm/amd/display: disable DPP RCG before DPP CLK enable

by Sasha Levin

From: Charlene Liu <Charlene.Liu(a)amd.com> [ Upstream commit 1bcd679209420305a86833bc357d50021909edaf ] [why] DPP CLK enable needs to disable DPPCLK RCG first. The DPPCLK_en in dccg should always be enabled when the corresponding pipe is enabled. Reviewed-by: Hansen Dsouza <hansen.dsouza(a)amd.com> Signed-off-by: Charlene Liu <Charlene.Liu(a)amd.com> Signed-off-by: Ray Wu <ray.wu(a)amd.com> Tested-by: Daniel Wheeler <daniel.wheeler(a)amd.com> Signed-off-by: Alex Deucher <alexander.deucher(a)amd.com> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- Based on my analysis of both the commit message and code changes, my answer is: **YES** This commit should be backported to stable kernel trees for the following reasons: ## Critical Hardware Sequencing Fix The commit addresses a fundamental hardware sequencing requirement where DPP (Display Pipes and Planes) Root Clock Gating (RCG) must be disabled before enabling the DPP clock. This is a critical timing constraint that, if violated, can cause severe system issues. ## Specific Code Evidence 1. **In `dccg35_update_dpp_dto()`**, the fix adds a crucial sequencing step: ```c + dccg35_set_dppclk_rcg(dccg, dpp_inst, false); REG_SET_2(DPPCLK_DTO_PARAM[dpp_inst], 0, DPPCLK0_DTO_PHASE, phase, DPPCLK0_DTO_MODULO, modulo); dcn35_set_dppclk_enable(dccg, dpp_inst, true); ``` This ensures RCG is disabled (false) before enabling the DPP clock. 2. **In `dcn35_enable_plane()`**, explicit clock control is added: ```c + /*make sure DPPCLK is on*/ + dccg->funcs->dccg_root_gate_disable_control(dccg, dpp->inst, true); + dpp->funcs->dpp_dppclk_control(dpp, false, true); ``` 3. **Removal of problematic init code** in `dcn35_init_hw()`: ```c - if (res_pool->dccg->funcs->dccg_root_gate_disable_control) { - for (i = 0; i < res_pool->pipe_count; i++) - res_pool->dccg->funcs->dccg_root_gate_disable_control(res_pool->dccg, i, 0); - } ``` ## Similarity to Previous Critical Fixes This commit follows the pattern of Similar Commit #1, which also addressed clock gating sequencing issues that could cause system hangs. The commit message explicitly states this is needed because "DPP CLK enable needs to disable DPPCLK RCG first." ## Impact and Risk Assessment - **Bug Fixed**: Incorrect clock sequencing that can cause system instability - **Scope**: Limited to DCN35 display hardware (recent AMD GPUs) - **Complexity**: Small, focused changes with clear purpose - **Risk**: Low risk of regression - adds proper sequencing without major architectural changes This fix meets all criteria for stable backporting: - Fixes a real bug affecting users (system stability) - Small and contained changes - No new features or architectural changes - Addresses hardware constraints that cannot be worked around The commit should be backported to all stable kernels that include DCN35 display support to ensure proper display functionality and system stability for users with affected AMD GPUs. .../amd/display/dc/dccg/dcn35/dcn35_dccg.c | 38 ++++++++++++------- .../amd/display/dc/hwss/dcn35/dcn35_hwseq.c | 21 ++++++---- 2 files changed, 38 insertions(+), 21 deletions(-) diff --git a/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c b/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c index b363f5360818d..ad910065f463f 100644 --- a/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c +++ b/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c @@ -391,6 +391,7 @@ static void dccg35_set_dppclk_rcg(struct dccg *dccg, struct dcn_dccg *dccg_dcn = TO_DCN_DCCG(dccg); + if (!dccg->ctx->dc->debug.root_clock_optimization.bits.dpp && enable) return; @@ -411,6 +412,8 @@ static void dccg35_set_dppclk_rcg(struct dccg *dccg, BREAK_TO_DEBUGGER(); break; } + //DC_LOG_DEBUG("%s: inst(%d) DPPCLK rcg_disable: %d\n", __func__, inst, enable ? 0 : 1); + } static void dccg35_set_dpstreamclk_rcg( @@ -1112,30 +1115,24 @@ static void dcn35_set_dppclk_enable(struct dccg *dccg, { struct dcn_dccg *dccg_dcn = TO_DCN_DCCG(dccg); + switch (dpp_inst) { case 0: REG_UPDATE(DPPCLK_CTRL, DPPCLK0_EN, enable); - if (dccg->ctx->dc->debug.root_clock_optimization.bits.dpp) - REG_UPDATE(DCCG_GATE_DISABLE_CNTL6, DPPCLK0_ROOT_GATE_DISABLE, enable); break; case 1: REG_UPDATE(DPPCLK_CTRL, DPPCLK1_EN, enable); - if (dccg->ctx->dc->debug.root_clock_optimization.bits.dpp) - REG_UPDATE(DCCG_GATE_DISABLE_CNTL6, DPPCLK1_ROOT_GATE_DISABLE, enable); break; case 2: REG_UPDATE(DPPCLK_CTRL, DPPCLK2_EN, enable); - if (dccg->ctx->dc->debug.root_clock_optimization.bits.dpp) - REG_UPDATE(DCCG_GATE_DISABLE_CNTL6, DPPCLK2_ROOT_GATE_DISABLE, enable); break; case 3: REG_UPDATE(DPPCLK_CTRL, DPPCLK3_EN, enable); - if (dccg->ctx->dc->debug.root_clock_optimization.bits.dpp) - REG_UPDATE(DCCG_GATE_DISABLE_CNTL6, DPPCLK3_ROOT_GATE_DISABLE, enable); break; default: break; } + //DC_LOG_DEBUG("%s: dpp_inst(%d) DPPCLK_EN = %d\n", __func__, dpp_inst, enable); } @@ -1163,14 +1160,18 @@ static void dccg35_update_dpp_dto(struct dccg *dccg, int dpp_inst, ASSERT(false); phase = 0xff; } + dccg35_set_dppclk_rcg(dccg, dpp_inst, false); REG_SET_2(DPPCLK_DTO_PARAM[dpp_inst], 0, DPPCLK0_DTO_PHASE, phase, DPPCLK0_DTO_MODULO, modulo); dcn35_set_dppclk_enable(dccg, dpp_inst, true); - } else + } else { dcn35_set_dppclk_enable(dccg, dpp_inst, false); + /*we have this in hwss: disable_plane*/ + //dccg35_set_dppclk_rcg(dccg, dpp_inst, true); + } dccg->pipe_dppclk_khz[dpp_inst] = req_dppclk; } @@ -1182,6 +1183,7 @@ static void dccg35_set_dppclk_root_clock_gating(struct dccg *dccg, if (!dccg->ctx->dc->debug.root_clock_optimization.bits.dpp) return; + switch (dpp_inst) { case 0: REG_UPDATE(DCCG_GATE_DISABLE_CNTL6, DPPCLK0_ROOT_GATE_DISABLE, enable); @@ -1198,6 +1200,8 @@ static void dccg35_set_dppclk_root_clock_gating(struct dccg *dccg, default: break; } + //DC_LOG_DEBUG("%s: dpp_inst(%d) rcg: %d\n", __func__, dpp_inst, enable); + } static void dccg35_get_pixel_rate_div( @@ -1521,28 +1525,30 @@ static void dccg35_set_physymclk_root_clock_gating( switch (phy_inst) { case 0: REG_UPDATE(DCCG_GATE_DISABLE_CNTL2, - PHYASYMCLK_ROOT_GATE_DISABLE, enable ? 1 : 0); + PHYASYMCLK_ROOT_GATE_DISABLE, enable ? 0 : 1); break; case 1: REG_UPDATE(DCCG_GATE_DISABLE_CNTL2, - PHYBSYMCLK_ROOT_GATE_DISABLE, enable ? 1 : 0); + PHYBSYMCLK_ROOT_GATE_DISABLE, enable ? 0 : 1); break; case 2: REG_UPDATE(DCCG_GATE_DISABLE_CNTL2, - PHYCSYMCLK_ROOT_GATE_DISABLE, enable ? 1 : 0); + PHYCSYMCLK_ROOT_GATE_DISABLE, enable ? 0 : 1); break; case 3: REG_UPDATE(DCCG_GATE_DISABLE_CNTL2, - PHYDSYMCLK_ROOT_GATE_DISABLE, enable ? 1 : 0); + PHYDSYMCLK_ROOT_GATE_DISABLE, enable ? 0 : 1); break; case 4: REG_UPDATE(DCCG_GATE_DISABLE_CNTL2, - PHYESYMCLK_ROOT_GATE_DISABLE, enable ? 1 : 0); + PHYESYMCLK_ROOT_GATE_DISABLE, enable ? 0 : 1); break; default: BREAK_TO_DEBUGGER(); return; } + //DC_LOG_DEBUG("%s: dpp_inst(%d) PHYESYMCLK_ROOT_GATE_DISABLE:\n", __func__, phy_inst, enable ? 0 : 1); + } static void dccg35_set_physymclk( @@ -1643,6 +1649,8 @@ static void dccg35_dpp_root_clock_control( return; if (clock_on) { + dccg35_set_dppclk_rcg(dccg, dpp_inst, false); + /* turn off the DTO and leave phase/modulo at max */ dcn35_set_dppclk_enable(dccg, dpp_inst, 1); REG_SET_2(DPPCLK_DTO_PARAM[dpp_inst], 0, @@ -1654,6 +1662,8 @@ static void dccg35_dpp_root_clock_control( REG_SET_2(DPPCLK_DTO_PARAM[dpp_inst], 0, DPPCLK0_DTO_PHASE, 0, DPPCLK0_DTO_MODULO, 1); + /*we have this in hwss: disable_plane*/ + //dccg35_set_dppclk_rcg(dccg, dpp_inst, true); } dccg->dpp_clock_gated[dpp_inst] = !clock_on; diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c index 922b8d71cf1aa..63077c1fad859 100644 --- a/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c +++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c @@ -241,11 +241,6 @@ void dcn35_init_hw(struct dc *dc) dc->res_pool->hubbub->funcs->allow_self_refresh_control(dc->res_pool->hubbub, !dc->res_pool->hubbub->ctx->dc->debug.disable_stutter); } - if (res_pool->dccg->funcs->dccg_root_gate_disable_control) { - for (i = 0; i < res_pool->pipe_count; i++) - res_pool->dccg->funcs->dccg_root_gate_disable_control(res_pool->dccg, i, 0); - } - for (i = 0; i < res_pool->audio_count; i++) { struct audio *audio = res_pool->audios[i]; @@ -901,12 +896,18 @@ void dcn35_init_pipes(struct dc *dc, struct dc_state *context) void dcn35_enable_plane(struct dc *dc, struct pipe_ctx *pipe_ctx, struct dc_state *context) { + struct dpp *dpp = pipe_ctx->plane_res.dpp; + struct dccg *dccg = dc->res_pool->dccg; + + /* enable DCFCLK current DCHUB */ pipe_ctx->plane_res.hubp->funcs->hubp_clk_cntl(pipe_ctx->plane_res.hubp, true); /* initialize HUBP on power up */ pipe_ctx->plane_res.hubp->funcs->hubp_init(pipe_ctx->plane_res.hubp); - + /*make sure DPPCLK is on*/ + dccg->funcs->dccg_root_gate_disable_control(dccg, dpp->inst, true); + dpp->funcs->dpp_dppclk_control(dpp, false, true); /* make sure OPP_PIPE_CLOCK_EN = 1 */ pipe_ctx->stream_res.opp->funcs->opp_pipe_clock_control( pipe_ctx->stream_res.opp, @@ -923,6 +924,7 @@ void dcn35_enable_plane(struct dc *dc, struct pipe_ctx *pipe_ctx, // Program system aperture settings pipe_ctx->plane_res.hubp->funcs->hubp_set_vm_system_aperture_settings(pipe_ctx->plane_res.hubp, &apt); } + //DC_LOG_DEBUG("%s: dpp_inst(%d) =\n", __func__, dpp->inst); if (!pipe_ctx->top_pipe && pipe_ctx->plane_state @@ -938,6 +940,8 @@ void dcn35_plane_atomic_disable(struct dc *dc, struct pipe_ctx *pipe_ctx) { struct hubp *hubp = pipe_ctx->plane_res.hubp; struct dpp *dpp = pipe_ctx->plane_res.dpp; + struct dccg *dccg = dc->res_pool->dccg; + dc->hwss.wait_for_mpcc_disconnect(dc, dc->res_pool, pipe_ctx); @@ -955,7 +959,8 @@ void dcn35_plane_atomic_disable(struct dc *dc, struct pipe_ctx *pipe_ctx) hubp->funcs->hubp_clk_cntl(hubp, false); dpp->funcs->dpp_dppclk_control(dpp, false, false); -/*to do, need to support both case*/ + dccg->funcs->dccg_root_gate_disable_control(dccg, dpp->inst, false); + hubp->power_gated = true; hubp->funcs->hubp_reset(hubp); @@ -967,6 +972,8 @@ void dcn35_plane_atomic_disable(struct dc *dc, struct pipe_ctx *pipe_ctx) pipe_ctx->top_pipe = NULL; pipe_ctx->bottom_pipe = NULL; pipe_ctx->plane_state = NULL; + //DC_LOG_DEBUG("%s: dpp_inst(%d)=\n", __func__, dpp->inst); + } void dcn35_disable_plane(struct dc *dc, struct dc_state *state, struct pipe_ctx *pipe_ctx) -- 2.39.5

4 weeks

1
101
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[PATCH 5.15] x86/its: Fix undefined reference to cpu_wants_rethunk_at()

by Pawan Gupta

Below error was reported in a 32-bit kernel build: static_call.c:(.ref.text+0x46): undefined reference to `cpu_wants_rethunk_at' make[1]: [Makefile:1234: vmlinux] Error This is because the definition of cpu_wants_rethunk_at() depends on CONFIG_STACK_VALIDATION which is only enabled in 64-bit mode. Define the empty function for CONFIG_STACK_VALIDATION=n, rethunk mitigation is anyways not supported without it. Reported-by: Guenter Roeck <linux(a)roeck-us.net> Fixes: 5d19a0574b75 ("x86/its: Add support for ITS-safe return thunk") Signed-off-by: Pawan Gupta <pawan.kumar.gupta(a)linux.intel.com> Link: https://lore.kernel.org/stable/0f597436-5da6-4319-b918-9f57bde5634a@roeck-u… --- arch/x86/include/asm/alternative.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h index 1797f80c10de..a5f704dbb4a1 100644 --- a/arch/x86/include/asm/alternative.h +++ b/arch/x86/include/asm/alternative.h @@ -98,7 +98,7 @@ static inline u8 *its_static_thunk(int reg) } #endif -#ifdef CONFIG_RETHUNK +#if defined(CONFIG_RETHUNK) && defined(CONFIG_STACK_VALIDATION) extern bool cpu_wants_rethunk(void); extern bool cpu_wants_rethunk_at(void *addr); #else -- 2.34.1

4 weeks, 1 day

2
1
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[merged mm-stable] mm-khugepaged-fix-race-with-folio-split-free-using-temporary-reference.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm/khugepaged: fix race with folio split/free using temporary reference has been removed from the -mm tree. Its filename was mm-khugepaged-fix-race-with-folio-split-free-using-temporary-reference.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Shivank Garg <shivankg(a)amd.com> Subject: mm/khugepaged: fix race with folio split/free using temporary reference Date: Mon, 26 May 2025 18:28:18 +0000 hpage_collapse_scan_file() calls is_refcount_suitable(), which in turn calls folio_mapcount(). folio_mapcount() checks folio_test_large() before proceeding to folio_large_mapcount(), but there is a race window where the folio may get split/freed between these checks, triggering: VM_WARN_ON_FOLIO(!folio_test_large(folio), folio) Take a temporary reference to the folio in hpage_collapse_scan_file(). This stabilizes the folio during refcount check and prevents incorrect large folio detection due to concurrent split/free. Use helper folio_expected_ref_count() + 1 to compare with folio_ref_count() instead of using is_refcount_suitable(). Link: https://lkml.kernel.org/r/20250526182818.37978-1-shivankg@amd.com Fixes: 05c5323b2a34 ("mm: track mapcount of large folios in single value") Signed-off-by: Shivank Garg <shivankg(a)amd.com> Reported-by: syzbot+2b99589e33edbe9475ca(a)syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/6828470d.a70a0220.38f255.000c.GAE@google.com Suggested-by: David Hildenbrand <david(a)redhat.com> Acked-by: David Hildenbrand <david(a)redhat.com> Acked-by: Dev Jain <dev.jain(a)arm.com> Reviewed-by: Baolin Wang <baolin.wang(a)linux.alibaba.com> Cc: Bharata B Rao <bharata(a)amd.com> Cc: Fengwei Yin <fengwei.yin(a)intel.com> Cc: Liam Howlett <liam.howlett(a)oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com> Cc: Mariano Pache <npache(a)redhat.com> Cc: Ryan Roberts <ryan.roberts(a)arm.com> Cc: Zi Yan <ziy(a)nvidia.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/khugepaged.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) --- a/mm/khugepaged.c~mm-khugepaged-fix-race-with-folio-split-free-using-temporary-reference +++ a/mm/khugepaged.c @@ -2293,6 +2293,17 @@ static int hpage_collapse_scan_file(stru continue; } + if (!folio_try_get(folio)) { + xas_reset(&xas); + continue; + } + + if (unlikely(folio != xas_reload(&xas))) { + folio_put(folio); + xas_reset(&xas); + continue; + } + if (folio_order(folio) == HPAGE_PMD_ORDER && folio->index == start) { /* Maybe PMD-mapped */ @@ -2303,23 +2314,27 @@ static int hpage_collapse_scan_file(stru * it's safe to skip LRU and refcount checks before * returning. */ + folio_put(folio); break; } node = folio_nid(folio); if (hpage_collapse_scan_abort(node, cc)) { result = SCAN_SCAN_ABORT; + folio_put(folio); break; } cc->node_load[node]++; if (!folio_test_lru(folio)) { result = SCAN_PAGE_LRU; + folio_put(folio); break; } - if (!is_refcount_suitable(folio)) { + if (folio_expected_ref_count(folio) + 1 != folio_ref_count(folio)) { result = SCAN_PAGE_COUNT; + folio_put(folio); break; } @@ -2331,6 +2346,7 @@ static int hpage_collapse_scan_file(stru */ present += folio_nr_pages(folio); + folio_put(folio); if (need_resched()) { xas_pause(&xas); _ Patches currently in -mm which might be from shivankg(a)amd.com are

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Linux-stable-mirror June 2025