From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EE862CCA470 for ; Fri, 3 Oct 2025 03:23:29 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 33A4110E0A6; Fri, 3 Oct 2025 03:23:29 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="UHOGf3iT"; dkim-atps=neutral Received: from mail-pf1-f179.google.com (mail-pf1-f179.google.com [209.85.210.179]) by gabe.freedesktop.org (Postfix) with ESMTPS id DF3AE10E0A6 for ; Fri, 3 Oct 2025 03:23:27 +0000 (UTC) Received: by mail-pf1-f179.google.com with SMTP id d2e1a72fcca58-77f1f29a551so2404665b3a.3 for ; Thu, 02 Oct 2025 20:23:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1759461807; x=1760066607; darn=lists.freedesktop.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=4MpfPEc8P9b4L2GNCySEMZpVOERhqW8EFBw6DoknkFk=; b=UHOGf3iTIs/j7Mb+ruxlcaVVBImG4WnY23rObMIw792O7JCBMF1SaQIBQIuNrtYy3G Fz7X9VkX1cGNHc8dBwVLDPe1VfUy1FBGXnNs2lssJ3fCBUYYWk1WBmuYe0BdTrgykFPo unB1PPsheZkWBd2ETzt9fljlg4o/veIQCf/DdEUYjpPoovKBpVu5iNpCOVgsGpKKKNb6 ktXppsOx+D/omW1Zaht31SyzU4grQfvHj5JYPdmPDW5bynjXBNykVSYjEGsW0ETwhs9U up+YQmu0yqq6IgIoBzkPJ/JQw7R2bv4zCwtmbj1k0RZ6fcE27MTW8/X+dmr3W59DxIVv +s0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1759461807; x=1760066607; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=4MpfPEc8P9b4L2GNCySEMZpVOERhqW8EFBw6DoknkFk=; b=FYTd7GjDelTrYWvbe80sBGQrqyGbRoQy/9ax6lyhvd3jGkVu2OpKyzIc8zRFTvW+YN mEcp6bg4Vl8Llx4Hv4jDsLTQLHZphEP0De8AShJfA/tzOkaYokHnEkPc5ojzlQbxAamQ YfnEA6Anrf/N/hAShmS7LNn6FKj/fQpFOnCPjFwQspwq/fgNcaiiXTPGIn+o6aKs68iP UhQfOCqWjWoKitwH5l7ONEEiQl0oJu6as4mnejvGru+OsDNMzULRlJSySVo4WamhGFC7 llqP0o9C5s6wEXX6/bFo5BXMWMflN0/7Z/e7EbwcUQSg24T2/GpI+RxMNLmju5oSXq/S j9Sg== X-Gm-Message-State: AOJu0Yxy/Y7CCADRBJ40Yfvc72cGcy6A/vnyjePZpmNa6uZDZ42tem+Z 60DE7YGumjxGiadEskogJfYVVeSNgFOAFylbhisowuyDOTcJP7cJa7qE X-Gm-Gg: ASbGncu8wN4UfbT1acBqbNfyetRQbYA9PBKLjJEvT3ExYmwqwmTEYpnlqA1nn1zhHnU VfPOG8RqOiXubSgKZfGk8qt7v0h4o+w23nf/xagthw1/TjC+2GYuiW1vdw8mmAdKCgHMzUSbEAR F1Pz6hbFdasCxbwQbscbSZYm3ovmrEftsChb34ye10xBiycOXDOtNViL1S0GbUofsHO8p/hgcTV NIzuniBH5UEcQGJRYfw90GU0J2wzee+00B/6K6gX11bGp7ky5c5opy8EhYXu8h/I2J9u84bK+Ko dqLYBHSv4kR8nz3Ct8f2afz1yJpcw5iAFHfAHMTp+Z6U3vfrcYpkj1e0Q6HUo9ODwlFKYkxYZBT 4mBVhsQ9PZocBtdUFJw8GP2KZEHtTHLTJ0IXxbgPxBG1+xVvY3J+SuBEzuNWG3Ymj6F+0WI3nw6 TEjoc= X-Google-Smtp-Source: AGHT+IHVZ5V7HiW9Rkw0s33+w+cQO1spnlPihGJa+P8ngoTWf74O/b6uIrMzfDZNNheYb8e6iNEHnA== X-Received: by 2002:a05:6a00:230b:b0:781:1dc6:4e69 with SMTP id d2e1a72fcca58-78c98a89454mr2351558b3a.14.1759461807296; Thu, 02 Oct 2025 20:23:27 -0700 (PDT) Received: from cmpatel-home.hsd1.or.comcast.net ([2601:1c0:5780:9200:326a:8939:a05c:b9d5]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-78b0206e81fsm3460145b3a.70.2025.10.02.20.23.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Oct 2025 20:23:26 -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 v3] drm/vblank: downgrade vblank wait timeout from WARN to error Date: Thu, 2 Oct 2025 20:23:03 -0700 Message-ID: <20251003032303.16518-1-chintanlike@gmail.com> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" When wait_event_timeout() in drm_wait_one_vblank() times out, the current WARN can cause unnecessary kernel panics in environments with panic_on_warn set (e.g. CI, fuzzing). These timeouts can happen under heavy scheduling pressure or in rare cases of delayed vblank handling, and are not always a kernel bug. Replace the WARN with drm_err() messages that report the timeout without crashing the system. Developers can still enable drm.debug to diagnose genuine problems. 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 v2: - Drop unnecessary in-code comment (suggested by Thomas Zimmermann) - Remove else branch, only log timeout case v3: - Use drm_err() instead of drm_dbg_kms() (suggested by Ville Syrjälä) - Remove unnecessary curr = drm_vblank_count() (suggested by Thomas Zimmermann) - Fix commit message wording (“invalid userspace calls” → “delayed vblank handling”) --- drivers/gpu/drm/drm_vblank.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index 46f59883183d..0664aea1b924 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -1305,7 +1305,8 @@ void drm_wait_one_vblank(struct drm_device *dev, unsigned int pipe) last != drm_vblank_count(dev, pipe), msecs_to_jiffies(100)); - drm_WARN(dev, ret == 0, "vblank wait timed out on crtc %i\n", pipe); + if (!ret) + drm_err(dev, "vblank wait timed out on crtc %i\n", pipe); drm_vblank_put(dev, pipe); } -- 2.43.0