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Thu, 4 Dec 2025 07:34:44 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id Xmc4EpQ5MWlHZAAAD6G6ig (envelope-from ); Thu, 04 Dec 2025 07:34:44 +0000 Message-ID: Date: Thu, 4 Dec 2025 08:34:43 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] drm/vblank: Increase timeout in drm_wait_one_vblank() To: Chintan Patel , maarten.lankhorst@linux.intel.com, maxime.ripard@kernel.org, airlied@gmail.com, simona@ffwll.ch Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, syzbot+147ba789658184f0ce04@syzkaller.appspotmail.com References: <20251028034337.6341-1-chintanlike@gmail.com> <2dae83e3-6fee-4e66-964e-c7baf46eecd8@suse.de> <67663eda-dce6-48e7-ad54-572bbce8b944@gmail.com> Content-Language: en-US From: Thomas Zimmermann Autocrypt: addr=tzimmermann@suse.de; keydata= xsBNBFs50uABCADEHPidWt974CaxBVbrIBwqcq/WURinJ3+2WlIrKWspiP83vfZKaXhFYsdg XH47fDVbPPj+d6tQrw5lPQCyqjwrCPYnq3WlIBnGPJ4/jreTL6V+qfKRDlGLWFjZcsrPJGE0 BeB5BbqP5erN1qylK9i3gPoQjXGhpBpQYwRrEyQyjuvk+Ev0K1Jc5tVDeJAuau3TGNgah4Yc hdHm3bkPjz9EErV85RwvImQ1dptvx6s7xzwXTgGAsaYZsL8WCwDaTuqFa1d1jjlaxg6+tZsB 9GluwvIhSezPgnEmimZDkGnZRRSFiGP8yjqTjjWuf0bSj5rUnTGiyLyRZRNGcXmu6hjlABEB AAHNJ1Rob21hcyBaaW1tZXJtYW5uIDx0emltbWVybWFubkBzdXNlLmRlPsLAjgQTAQgAOAIb AwULCQgHAgYVCgkICwIEFgIDAQIeAQIXgBYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJftODH AAoJEGgNwR1TC3ojx1wH/0hKGWugiqDgLNXLRD/4TfHBEKmxIrmfu9Z5t7vwUKfwhFL6hqvo lXPJJKQpQ2z8+X2vZm/slsLn7J1yjrOsoJhKABDi+3QWWSGkaGwRJAdPVVyJMfJRNNNIKwVb U6B1BkX2XDKDGffF4TxlOpSQzdtNI/9gleOoUA8+jy8knnDYzjBNOZqLG2FuTdicBXblz0Mf vg41gd9kCwYXDnD91rJU8tzylXv03E75NCaTxTM+FBXPmsAVYQ4GYhhgFt8S2UWMoaaABLDe 7l5FdnLdDEcbmd8uLU2CaG4W2cLrUaI4jz2XbkcPQkqTQ3EB67hYkjiEE6Zy3ggOitiQGcqp j//OwE0EWznS4AEIAMYmP4M/V+T5RY5at/g7rUdNsLhWv1APYrh9RQefODYHrNRHUE9eosYb T6XMryR9hT8XlGOYRwKWwiQBoWSDiTMo/Xi29jUnn4BXfI2px2DTXwc22LKtLAgTRjP+qbU6 3Y0xnQN29UGDbYgyyK51DW3H0If2a3JNsheAAK+Xc9baj0LGIc8T9uiEWHBnCH+RdhgATnWW GKdDegUR5BkDfDg5O/FISymJBHx2Dyoklv5g4BzkgqTqwmaYzsl8UxZKvbaxq0zbehDda8lv hFXodNFMAgTLJlLuDYOGLK2AwbrS3Sp0AEbkpdJBb44qVlGm5bApZouHeJ/+n+7r12+lqdsA EQEAAcLAdgQYAQgAIAIbDBYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJftOH6AAoJEGgNwR1T C3ojVSkIALpAPkIJPQoURPb1VWjh34l0HlglmYHvZszJWTXYwavHR8+k6Baa6H7ufXNQtThR yIxJrQLW6rV5lm7TjhffEhxVCn37+cg0zZ3j7zIsSS0rx/aMwi6VhFJA5hfn3T0TtrijKP4A SAQO9xD1Zk9/61JWk8OysuIh7MXkl0fxbRKWE93XeQBhIJHQfnc+YBLprdnxR446Sh8Wn/2D Ya8cavuWf2zrB6cZurs048xe0UbSW5AOSo4V9M0jzYI4nZqTmPxYyXbm30Kvmz0rYVRaitYJ 4kyYYMhuULvrJDMjZRvaNe52tkKAvMevcGdt38H4KSVXAylqyQOW5zvPc4/sq9c= In-Reply-To: <67663eda-dce6-48e7-ad54-572bbce8b944@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.997]; MIME_GOOD(-0.10)[text/plain]; RCPT_COUNT_SEVEN(0.00)[8]; FREEMAIL_TO(0.00)[gmail.com,linux.intel.com,kernel.org,ffwll.ch]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; TAGGED_RCPT(0.00)[147ba789658184f0ce04]; MID_RHS_MATCH_FROM(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; TO_DN_SOME(0.00)[] X-Spam-Level: X-Spam-Flag: NO X-Spam-Score: -2.80 Hi Am 04.12.25 um 04:44 schrieb Chintan Patel: > 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: syzbot+147ba789658184f0ce04@syzkaller.appspotmail.com >>> Closes: https://syzkaller.appspot.com/bug?extid=147ba789658184f0ce04 >>> Tested-by: syzbot+147ba789658184f0ce04@syzkaller.appspotmail.com >>> Signed-off-by: Chintan Patel >> >> Reviewed-by: Thomas Zimmermann > > 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. It's on its way already. This patch has been merged as commit f050da08a4ed ("drm/vblank: Increase timeout in drm_wait_one_vblank()"). It was part of the recent PR for v6.19-rc1. Best regards Thomas [1] https://lore.kernel.org/dri-devel/CAPM=9tySHmq2KLAvW95MeKcb-37gZBhHTY5hf4dCTgUFLd+RKg@mail.gmail.com/T/#u > >>> >>> 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); >> > -- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)