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Mon, 27 Oct 2025 20:44:24 -0700 (PDT) Received: from cmpatel-home.hsd1.or.comcast.net ([2601:1c0:5780:9200:7eda:5d15:414e:cb9e]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-b712f0c0b1asm8946849a12.32.2025.10.27.20.44.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Oct 2025 20:44:23 -0700 (PDT) From: Chintan Patel To: maarten.lankhorst@linux.intel.com, maxime.ripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, syzbot+147ba789658184f0ce04@syzkaller.appspotmail.com, Chintan Patel Subject: [PATCH v4] drm/vblank: Increase timeout in drm_wait_one_vblank() Date: Mon, 27 Oct 2025 20:43:37 -0700 Message-ID: <20251028034337.6341-1-chintanlike@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable 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. Reported-by: syzbot+147ba789658184f0ce04@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D147ba789658184f0ce04 Tested-by: syzbot+147ba789658184f0ce04@syzkaller.appspotmail.com Signed-off-by: Chintan Patel 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= Syrj=C3=A4l=C3=A4) - Removed unnecessary curr =3D drm_vblank_count() (suggested by Thomas Zim= mermann) - Fixed commit message wording ("invalid userspace calls" =E2=86=92 "delay= ed vblank handling") v4: - Keep the original drm_WARN() to catch genuine kernel issues - Increased timeout from 100ms =E2=86=92 1000ms to reduce spurious WARNs (= suggested by Thomas Zimmermann) Reviewed-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, unsi= gned int pipe) =20 ret =3D wait_event_timeout(vblank->queue, last !=3D drm_vblank_count(dev, pipe), - msecs_to_jiffies(100)); + msecs_to_jiffies(1000)); =20 drm_WARN(dev, ret =3D=3D 0, "vblank wait timed out on crtc %i\n", pipe); =20 --=20 2.43.0