From d5a480b44b189bad1d67df5d4c5ed9e6c750e8f2 Mon Sep 17 00:00:00 2001 From: "Xiangliang.Yu" Date: Fri, 20 Oct 2017 17:21:40 +0800 Subject: [PATCH] drm/amdgpu: fix kernel hang when starting VNC server MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit After starting VNC server or running CTS test, kernel will hang and can see below call trace: [961816] INFO: task khugepaged:42 blocked for more than 120 seconds. [968581] Tainted: G OE 4.13.0 #1 [973495] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [980962] khugepaged D 0 42 2 0x00000000 [980967] Call Trace: [980977] __schedule+0x28d/0x890 [980982] schedule+0x36/0x80 [980986] rwsem_down_read_failed+0x139/0x1c0 [980991] ? update_curr+0x100/0x1c0 [981004] call_rwsem_down_read_failed+0x18/0x30 [981007] down_read+0x20/0x40 [981012] khugepaged_scan_mm_slot+0x78/0x1ac0 [981018] ? __switch_to+0x23e/0x4a0 [981022] ? finish_task_switch+0x79/0x240 [981026] khugepaged+0x146/0x480 [981031] ? remove_wait_queue+0x60/0x60 [981035] kthread+0x109/0x140 [981037] ? khugepaged_scan_mm_slot+0x1ac0/0x1ac0 [981039] ? kthread_park+0x60/0x60 [981044] ret_from_fork+0x25/0x30 After checking code and found 'commit b72cf4fca2bb7 ("drm/amdgpu: move taking mmap_sem into get_user_pages v2")' forget to drop one case of up_read. Signed-off-by: Xiangliang.Yu Reviewed-by: Christian König Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c index 951d625bbdd7..14aff2f15a94 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c @@ -328,7 +328,7 @@ int amdgpu_gem_userptr_ioctl(struct drm_device *dev, void *data, r = amdgpu_ttm_tt_get_user_pages(bo->tbo.ttm, bo->tbo.ttm->pages); if (r) - goto unlock_mmap_sem; + goto release_object; r = amdgpu_bo_reserve(bo, true); if (r) @@ -353,9 +353,6 @@ int amdgpu_gem_userptr_ioctl(struct drm_device *dev, void *data, free_pages: release_pages(bo->tbo.ttm->pages, bo->tbo.ttm->num_pages, false); -unlock_mmap_sem: - up_read(¤t->mm->mmap_sem); - release_object: drm_gem_object_put_unlocked(gobj); -- GitLab