This is a note to let you know that I've just added the patch titled drm/vkms: fix misuse of WARN_ON to the 5.4-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-vkms-fix-misuse-of-warn_on.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 8f9d6bbd3a43b40b67c1d6d0e07dc4ccd0999a3a Author: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Date: Sat Mar 20 14:28:40 2021 +0100 drm/vkms: fix misuse of WARN_ON [ Upstream commit b4142fc4d52d051d4d8df1fb6c569e5b445d369e ] vkms_vblank_simulate() uses WARN_ON for timing-dependent condition (timer overrun). This is a mis-use of WARN_ON, WARN_ON must be used to denote kernel bugs. Use pr_warn() instead. Signed-off-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Reported-by: syzbot+4fc21a003c8332eb0bdd@xxxxxxxxxxxxxxxxxxxxxxxxx Cc: Rodrigo Siqueira <rodrigosiqueiramelo@xxxxxxxxx> Cc: Melissa Wen <melissa.srw@xxxxxxxxx> Cc: Haneen Mohammed <hamohammed.sa@xxxxxxxxx> Cc: Daniel Vetter <daniel@xxxxxxxx> Cc: David Airlie <airlied@xxxxxxxx> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Acked-by: Melissa Wen <melissa.srw@xxxxxxxxx> Signed-off-by: Melissa Wen <melissa.srw@xxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20210320132840.1315853-1-dvyukov@xxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c index 927dafaebc76..8b01fae65f43 100644 --- a/drivers/gpu/drm/vkms/vkms_crtc.c +++ b/drivers/gpu/drm/vkms/vkms_crtc.c @@ -20,7 +20,8 @@ static enum hrtimer_restart vkms_vblank_simulate(struct hrtimer *timer) ret_overrun = hrtimer_forward_now(&output->vblank_hrtimer, output->period_ns); - WARN_ON(ret_overrun != 1); + if (ret_overrun != 1) + pr_warn("%s: vblank timer overrun\n", __func__); ret = drm_crtc_handle_vblank(crtc); if (!ret)