From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 B8EDC3E0C55; Tue, 26 May 2026 11:35:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779795314; cv=none; b=nPgd0OK6v9lLTVqQyypttIe2H5LeUqUmUnUmdxjl1fgggDERr2wosjbjAizS7xZXrhJlPVrbEhCtECKFtzauC4ohh3uSSo89QoDh4iUaGGPaDhCsLu00cD4n4kAWk1GG2DdKHnOQ77D9DBYYGZYSamSPATY8p+LkTOsHOoZOXQw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779795314; c=relaxed/simple; bh=2H3H3vnC2GwG0fDzZ6w637YY6pI9aFKfjn1RibsbrmE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ia5i4acpCQYzPSX2x70KB5zhTdua5sF+uDMux8riPGlLV8zT4dAuUFzpRBoubYcApPtWQhFSLdYRsjBqnwXmS/uoIsHwjDJ/LmFpV0wuauya3Lk9LxqjRu7UICzIml6r+/QRaKqsWWA5x+emY9CJuOp3yEPyNv38dRbPWUAFKoE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NBpmCATl; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NBpmCATl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 56E051F000E9; Tue, 26 May 2026 11:35:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779795313; bh=XAFFB/ti5ppyZh8MzLYmcCCCoGstaLaSac5HP7Oym30=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=NBpmCATlSk82CG+IjXD3NxX/P+FXuwztclyQ9bxhPOji4foWcNghs5hT2Nif2/BhN 5LEbXKSPAZC8waxhBCtNJLow5qzi0h+zq2ky3HGiRnWgexPmgC65RRbZyiONGuhcf+ 9PrVGuEp9e2MzpI7Cd39vB+TCS06sWLD1wReWMXQU1jCDaDiL0c5jAaDCf53KlbpX0 YxM04pnnwhkrboup/wJQVcU/MYdsTzDUbiQ8ynKgbg4vFq8RRQDBGMboKR8yXugEkZ QYFNgFkyBI4jle9UBwq+82qnyYVMGKdIGq5jfTQDHbee43MdA4vSWQvHHMSQUonmEs E+WqatJb0KqQg== From: Sasha Levin To: stable@vger.kernel.org, gregkh@linuxfoundation.org Cc: Sasha Levin , 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>, w15303746062@163.com Subject: Re: [PATCH 6.18.y 0/5] drm/vkms: Backport generic vblank timer to fix ABBA deadlock Date: Tue, 26 May 2026 07:35:05 -0400 Message-ID: <20260525231000.agent5-0001@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260525131610.608273-1-w15303746062@163.com> References: <9c4a68c4-43a3-4a9b-a131-9570174c8df3@linux.intel.com> <20260525131610.608273-1-w15303746062@163.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > [PATCH 6.18.y 0/5] drm/vkms: Backport generic vblank timer to fix ABBA deadlock > > 1/5 drm/vblank: Add vblank timer (74afeb812850) > 2/5 drm/vblank: Add CRTC helpers for simple use cases (d54dbb5963bd) > 3/5 drm/vkms: Convert to DRM's vblank timer (02e2681ffe1a) > 4/5 drm/atomic: Increase timeout in drm_atomic_helper_wait_for_vblanks() (79ae8510b5b8) > 5/5 drm/vblank: Fix kernel docs for vblank timer (3946d3ba9934) Thanks for putting this together. Looking at the five commits: - 1/5 (74afeb812850) is the one that actually fixes the ABBA deadlock you observed under Syzkaller; it adds the generic vblank timer that replaces the open-coded vkms hrtimer path. - 2/5 (d54dbb5963bd) adds new CRTC helpers for "simple use cases". No Fixes:/Cc:stable, no described bug. - 3/5 (02e2681ffe1a) is a refactor that converts vkms to the new helpers. No Fixes:/Cc:stable, no described bug. - 4/5 (79ae8510b5b8) is a v7.1-rc1 timeout bump that depends on 1/5. It is not yet in any released stable, so applying it to 6.18.y would put it on an LTS before any LTS contains it. - 5/5 (3946d3ba9934) is a doc fix for 1/5. Per stable-kernel-rules, what I need to queue is the minimum set that fixes the bug. Could you explain, per patch, why 2/5..5/5 are required to make 1/5 work / are required to actually fix the deadlock? If only 1/5 is needed, please resend just that one with your Signed-off-by added (the carried patches today only have Thomas's S-o-b, which breaks the chain of custody on a stable submission). -- Thanks, Sasha