From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EF73E357D0B; Mon, 25 May 2026 13:17:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779715042; cv=none; b=QnVazqOeF4otlxGJv+rHamM5k6BkyFVkaGb5jXEhlEXdWfd7RHdNVupG+R7XGFe0+tn3+CooFpmh78YLvURRbWYxRu4lngHH29fWr+8a704/bijWAi759WlgnduO6+YGGHg1UJ0rBthiuZLSrCTwdlOVoNwZviHHvaMpt/huyWo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779715042; c=relaxed/simple; bh=6NLJbUHriJcEPTHc/gZJQ9HqrSvmrLir58qBUwmC6K0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=V0GyIkWHPFsPKzNmykbZ6LLTsbkurcvd7eGIVtUfBQ2cea3rRPzjOPNIHpfvXzpmYi8zXKd0oLzfinMXeWVNnmq/ES3R1YEX/sc9oRuOzlGjL0pDDB+mMx91/lm5WVZjohTI/QJDGzcJowTSkklN9oC5fgt8QtdvW8AAiFw2Lok= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=ViIADVMJ; arc=none smtp.client-ip=117.135.210.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="ViIADVMJ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=rc ojwpS/HH3aFSbpC+5s77qh50pJ7oQ8VBYS0FcRMdM=; b=ViIADVMJK3C/AOjGlo Dcx1Y51s2m8Z+gon422bl0ZtGWgdx3oVnXFug1Y8Oe6XCXC3Ib2xvpSg7q+sVSvr 3ezztEVwQsCcKFbsePkNweXYsXIFQ+FKAYGm0woorvrTVDP+Yly0B74Fedj3AJxD CGkdqomKiBMpTF77maX4Ht+h4= Received: from 163.com (unknown []) by gzga-smtp-mtada-g0-3 (Coremail) with SMTP id _____wCn6zidSxRqC7WEDQ--.19334S2; Mon, 25 May 2026 21:16:21 +0800 (CST) From: w15303746062@163.com To: stable@vger.kernel.org, gregkh@linuxfoundation.org Cc: tzimmermann@suse.de, maarten.lankhorst@linux.intel.com, mripard@kernel.org, louis.chauvet@bootlin.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Mingyu Wang <25181214217@stu.xidian.edu.cn> Subject: [PATCH 6.18.y 0/5] drm/vkms: Backport generic vblank timer to fix ABBA deadlock Date: Mon, 25 May 2026 21:16:05 +0800 Message-Id: <20260525131610.608273-1-w15303746062@163.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <9c4a68c4-43a3-4a9b-a131-9570174c8df3@linux.intel.com> References: <9c4a68c4-43a3-4a9b-a131-9570174c8df3@linux.intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wCn6zidSxRqC7WEDQ--.19334S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7KFykWF1rGF1kur43KF1Utrb_yoW8uF48pF sxJryayr45JFZxJwnxAFs7Z3W5ZayrXrWkKr9rK3s5Zw1FyF17AF18Jw43WFWUJrnrZr42 qrnFyr1Uur1UCrJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07j5_-PUUUUU= X-CM-SenderInfo: jzrvjiatxuliiws6il2tof0z/xtbC-wWbf2oUS6UmKAAA3A From: Mingyu Wang <25181214217@stu.xidian.edu.cn> Hi Greg and all, This patch series backports the generic DRM vblank timer infrastructure and converts the vkms driver to use it, specifically targeting the 6.18.y stable branch. During local fuzzing with Syzkaller, an RCU preempt stall (ABBA deadlock) was consistently observed in the 6.18.y vkms driver. This deadlock occurs between the legacy drm_vblank_disable_and_save() function and the vkms_vblank_simulate() hrtimer callback. A previous localized patch was submitted to address this in 6.18.y using hrtimer_try_to_cancel. However, as discussed with Greg KH and Maarten Lankhorst on the mailing list, the correct and most maintainable approach is to backport the mainline commits that inherently resolve this by removing the custom vkms hrtimer entirely. Following Maarten's roadmap, this series cherry-picks the exact dependency chain from mainline to introduce the drm_vblank_helper infrastructure and migrate vkms to it. The series applies smoothly to 6.18.y and completely resolves the soft lockup in the fuzzing environment. Thanks, Mingyu Wang Thomas Zimmermann (5): drm/vblank: Add vblank timer drm/vblank: Add CRTC helpers for simple use cases drm/vkms: Convert to DRM's vblank timer drm/atomic: Increase timeout in drm_atomic_helper_wait_for_vblanks() drm/vblank: Fix kernel docs for vblank timer Documentation/gpu/drm-kms-helpers.rst | 12 ++ drivers/gpu/drm/Makefile | 3 +- drivers/gpu/drm/drm_atomic_helper.c | 2 +- drivers/gpu/drm/drm_vblank.c | 172 +++++++++++++++++++++- drivers/gpu/drm/drm_vblank_helper.c | 176 +++++++++++++++++++++++ drivers/gpu/drm/vkms/vkms_crtc.c | 83 +---------- drivers/gpu/drm/vkms/vkms_drv.h | 2 - include/drm/drm_modeset_helper_vtables.h | 12 ++ include/drm/drm_vblank.h | 32 +++++ include/drm/drm_vblank_helper.h | 56 ++++++++ 10 files changed, 468 insertions(+), 82 deletions(-) create mode 100644 drivers/gpu/drm/drm_vblank_helper.c create mode 100644 include/drm/drm_vblank_helper.h -- 2.34.1