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 of up_read
usage.
Signed-off-by: Xiangliang.Yu <Xiangliang.Yu at amd.com>
---
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 fb72edc..08b37c2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -323,7 +323,7 @@ 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)
@@ -348,9 +348,6 @@ 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);
--
2.7.4
