Hi Thomas,
On 10/28/25 10:14, Thomas Zimmermann wrote:
Am 28.10.25 um 04:43 schrieb Chintan Patel:
Currently, wait_event_timeout() in drm_wait_one_vblank() uses a 100ms
timeout. Under heavy scheduling pressure or rare delayed vblank
handling, this can trigger WARNs unnecessarily.
Increase the timeout to 1000ms to reduce spurious WARNs, while still
catching genuine issues.
Thanks a lot.
Reported-by: [email protected]
Closes: https://syzkaller.appspot.com/bug?extid=147ba789658184f0ce04
Tested-by: [email protected]
Signed-off-by: Chintan Patel <[email protected]>
Reviewed-by: Thomas Zimmermann <[email protected]>
Gentle ping on this patch. Please let me know if there are any issues
with the patch, or if it requires any changes or further testing.
v2:
- Dropped unnecessary in-code comment (suggested by Thomas Zimmermann)
- Removed else branch, only log timeout case
v3:
- Replaced drm_dbg_kms()/manual logging with drm_err() (suggested by
Ville Syrjälä)
- Removed unnecessary curr = drm_vblank_count() (suggested by Thomas
Zimmermann)
- Fixed commit message wording ("invalid userspace calls" → "delayed
vblank handling")
v4:
- Keep the original drm_WARN() to catch genuine kernel issues
- Increased timeout from 100ms → 1000ms to reduce spurious WARNs
(suggested by Thomas Zimmermann)
---
drivers/gpu/drm/drm_vblank.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 46f59883183d..f779103b261b 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -1303,7 +1303,7 @@ void drm_wait_one_vblank(struct drm_device *dev,
unsigned int pipe)
ret = wait_event_timeout(vblank->queue,
last != drm_vblank_count(dev, pipe),
- msecs_to_jiffies(100));
+ msecs_to_jiffies(1000));
drm_WARN(dev, ret == 0, "vblank wait timed out on crtc %i\n",
pipe);
