From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from vmicros1.altlinux.org (vmicros1.altlinux.org [194.107.17.57]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A06D21CFBA; Wed, 15 Apr 2026 12:24:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=194.107.17.57 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776256115; cv=none; b=VLCj4iy06LLwdmTuc8wbHioetL+IdM9KpT+QyNBN2SJMA4I81BYYvn30C3+qSnKO+7Aen+rGuqJf9OqG2CLv6w7cju/qx6DABnh5aQTyadysp7zM6cO5kJRb4lYy8kEfbYMc+ZRrb+7aJEwMFknhhRif0QBWcrj1Oos1EqFyb3I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776256115; c=relaxed/simple; bh=WhMRwHxqrUmLB1iTZPrhNMa7cyGhlCwbvs9D5uo4/7U=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UsjUX8kW/WJaqhU4V7IWhLqtSMtq3knZIpJRHR0EgK6kpX4rCP3aATu1olyduTX8yKOg+7ldic257emCC93h+ZNAaBE3jSe6zzADAI4TAh7f/6iwQLIecOf6LIAF+lNQo03fplXrZBMuxa6TC0GQ1BO6CousT7KiLD7dJSI9Q00= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=altlinux.org; spf=pass smtp.mailfrom=altlinux.org; arc=none smtp.client-ip=194.107.17.57 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=altlinux.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=altlinux.org Received: from imap.altlinux.org (imap.altlinux.org [194.107.17.38]) by vmicros1.altlinux.org (Postfix) with ESMTP id 28ED172C8CC; Wed, 15 Apr 2026 15:24:03 +0300 (MSK) Received: from altlinux.org (unknown [193.43.10.9]) by imap.altlinux.org (Postfix) with ESMTPSA id 1B06E36D00D0; Wed, 15 Apr 2026 15:24:03 +0300 (MSK) Date: Wed, 15 Apr 2026 15:24:02 +0300 From: Vitaly Chikunov To: Thorsten Leemhuis , Sasha Levin Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, gregkh@linuxfoundation.org, regressions@lists.linux.dev, Matt Roper , Rodrigo Vivi Subject: Re: [regression] Re: Linux 6.12.75 Message-ID: References: <20260304131402.83200-1-sashal@kernel.org> <20260304131402.83200-2-sashal@kernel.org> 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=koi8-r Content-Disposition: inline In-Reply-To: Thorsten, Sasha, On Tue, Apr 14, 2026 at 06:24:38PM +0300, Vitaly Chikunov wrote: > On Tue, Apr 14, 2026 at 04:57:38PM +0300, Vitaly Chikunov wrote: > > On Tue, Apr 14, 2026 at 03:17:38AM +0300, Vitaly Chikunov wrote: > > > On Mon, Apr 13, 2026 at 05:17:30PM +0300, Vitaly Chikunov wrote: > > > > On Mon, Apr 13, 2026 at 01:33:18PM +0200, Thorsten Leemhuis wrote: > > > > > On 4/2/26 10:44, Vitaly Chikunov wrote: > > > > > > > > > > > > 1. I cannot find this commit posted on lore.kernel.org to report to > > > > > > exact patch. > > > > > > > > > > > > | From: Matt Roper > > > > > > | Date: Tue, 10 Sep 2024 16:47:29 -0700 > > > > > > | Subject: [PATCH 6.12/sisyphus] drm/xe: Switch MMIO interface to take xe_mmio > > > > > > | instead of xe_gt > > > > > > | > > > > > > | [ Upstream commit a84590c5ceb354d2e9f7f6812cfb3a9709e14afa ] > > > > > > | > > > > > > | Since much of the MMIO register access done by the driver is to non-GT > > > > > > | registers, use of 'xe_gt' in these interfaces has been a long-standing > > > > > > | design flaw that's been hard to disentangle. > > > > > > [...] > > > > > > > > > > > > 2. After this patch applied to 6.12.75 there is kernel NULL pointer > > > > > > dereference BUG on MSI MAG H670 12th Gen Intel(R) Core(TM) i5-12600K > > > > > > with ASRock Intel Arc B580 Challenger [Alchemist], 12GB: > > > > > > [...] > > > > > > The commit is found not by a git bisect (since it's reported by end > > > > > > user and I cannot reproduce it on my hardware) but (by analyzing dmesg) > > > > > > with: > > > > > > [...] > > > > > > Then finding the suspecting commit: > > > > > > > > > > > > $ git log --oneline -G'XE_LUNARLAKE' v6.12.74..v6.12.75 > > > > > > 26a40327c25c drm/xe: Switch MMIO interface to take xe_mmio instead of xe_gt > > > > > > > > > > > > 6.18 and above are not affected by the bug. Also, they have another commit > > > > > > modifying the line which is not present in 6.12 branch: > > > > > > [...] > > > > > > Related drm/xe bug report https://gitlab.freedesktop.org/drm/xe/kernel/-/work_items/7661 > > > > > Nobody reacted to this and it seems the gitlab ticket is stalled, too. > > > > > So let me ask: can this be resolved by reverting 26a40327c25c in 6.12.y? > > > > > > It's turned out these two commits are revertible together: > > > > > > 8f6848b2f6ea ("drm/xe/mmio: Avoid double-adjust in 64-bit reads") > > > 26a40327c25c ("drm/xe: Switch MMIO interface to take xe_mmio instead of xe_gt") > > > > > > I am going to ask the users to test this. > > > > After testing revert of these two commits, users report that regress > > does not appear, kernel boots without panic and there is no video artifacts. > > After analyzing the problem slightly deeper, it seems that there is > uninitialized mmio.tile issue. Which is fixed in mainline commit > > 58548b91101f ("drm/xe: Defer gt->mmio initialization until after multi-tile setup") Applying this commit to v6.12.81 does not resolve the regress. Thus, I would suggest reverting commits 26a40327c25c and 8f6848b2f6ea. Thanks, > > The commit also have tag: > > Fixes: fa599b8c95a7 ("drm/xe: Populate GT's mmio iomap from tile during init") > > The commit fa599b8c95a7 is picked into 6.12.75 as 0b433e086b9f, but the > fix is not. Piking it may be the better way to fix the regression than > the revert of the two aforementioned commits. > > I will try to pick the fix, test, and report if it resolves the regress. > > Thanks, > > > > > > So, I kindly ask to revert them from 6.12.y branch if they aren't > > critical. > > > > Thanks, > > > > > > > > Thanks, > > > > > > > > > > > As of me, this is not easy to revert, as it depends on many other > > > > commits, and git does not have tooling to determine all dependant > > > > commits for revert. I hope someone from drm subsystem notices this to > > > > work on it, or Sasha can pull missing commits or revert this (obviously, > > > > he have tooling for this, but I was unable to find it). [I found > > > > obsolete references to deps but is seems not used for years and Python > > > > git-deps tool seems broken.] > > > > > > > > What I found is, offending commit is picked due to > > > > > > > > Stable-dep-of: 4a9b4e1fa52a ("drm/xe/mmio: Avoid double-adjust in 64-bit reads") > > > > > > > > Which, perhaps, needs to be reverted. > > > > > > > > Offending commit 26a40327c25c is not tracked in lore. > > > > It's part of 9 piece patchset, perhaps they are logically dependent too, > > > > so need to be reverted together. > > > > > > > > The possible fix is part of 6 piece patchset, which does not cherry-pick > > > > easily due to conflicts. > > > > > > > > If someone can produce correct fix we can participate in the tests. > > > > > > > > Thanks, > > > > > > > > > > > > > > Ciao, Thorsten