[regression] Re: Linux 6.12.75

[regression] Re: Linux 6.12.75

[Vitaly Chikunov]

Sasha,

1. I cannot find this commit posted on lore.kernel.org to report to
exact patch.

| From: Matt Roper <matthew.d.roper@intel.com>
| 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.
| 
| To avoid a flag day across the whole driver, munge the function names
| and add temporary compatibility macros with the original function names
| that can accept either the new xe_mmio or the old xe_gt structure as a
| parameter.  This will allow us to slowly convert parts of the driver
| over to the new interface independently.
| 
| Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
| Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
| Link: https://patchwork.freedesktop.org/patch/msgid/20240910234719.3335472-54-matthew.d.roper@intel.com
| Stable-dep-of: 4a9b4e1fa52a ("drm/xe/mmio: Avoid double-adjust in 64-bit reads")
| Signed-off-by: Sasha Levin <sashal@kernel.org>
| ---
|  drivers/gpu/drm/xe/xe_mmio.h  |  72 +++++++++++++++----
|  drivers/gpu/drm/xe/xe_trace.h |   7 +-
|  drivers/gpu/drm/xe/xe_mmio.c  | 131 ++++++++++++++++------------------
|  3 files changed, 124 insertions(+), 86 deletions(-)

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:

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI
  CPU: 8 UID: 0 PID: 310 Comm: (udev-worker) Not tainted 6.12.79-6.12-alt1 #1
  Hardware name: Micro-Star International Co., Ltd. MS-7D25/MAG H670 TOMAHAWK WIFI DDR4(MS-7D25), BIOS H.N0 07/31/2025
  RIP: 0010:__xe_mmio_read32+0x23/0xe0 [xe]

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:

  (gdb) list *__xe_mmio_read32+0x23
  0x35723 is in __xe_mmio_read32 (drivers/gpu/drm/xe/xe_mmio.c:195).
  190     static void mmio_flush_pending_writes(struct xe_mmio *mmio)
  191     {
  192     #define DUMMY_REG_OFFSET        0x130030
  193             int i;
  194
  195             if (mmio->tile->xe->info.platform != XE_LUNARLAKE)
  196                     return;
  197
  198             /* 4 dummy writes */
  199             for (i = 0; i < 4; i++)

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:

  ac596dee8008 drm/xe: Move Wa_15015404425 to use the new XE_DEVICE_WA macro

Thanks,

#regzbot introduced: v6.12.75

Related drm/xe bug report https://gitlab.freedesktop.org/drm/xe/kernel/-/work_items/7661

On Wed, Mar 04, 2026 at 08:14:02AM -0500, Sasha Levin wrote:
> diff --git a/drivers/gpu/drm/xe/xe_mmio.c b/drivers/gpu/drm/xe/xe_mmio.c
> index 3fd462fda6255..449e6c5636712 100644
> --- a/drivers/gpu/drm/xe/xe_mmio.c
> +++ b/drivers/gpu/drm/xe/xe_mmio.c
> @@ -172,122 +180,118 @@ int xe_mmio_init(struct xe_device *xe)
> -static void mmio_flush_pending_writes(struct xe_gt *gt)
> +static void mmio_flush_pending_writes(struct xe_mmio *mmio)
>  {
>  #define DUMMY_REG_OFFSET	0x130030
> -	struct xe_tile *tile = gt_to_tile(gt);
>  	int i;
>  
> -	if (tile->xe->info.platform != XE_LUNARLAKE)
> +	if (mmio->tile->xe->info.platform != XE_LUNARLAKE)
>  		return;
>  
>  	/* 4 dummy writes */
>  	for (i = 0; i < 4; i++)
> -		writel(0, tile->mmio.regs + DUMMY_REG_OFFSET);
> +		writel(0, mmio->regs + DUMMY_REG_OFFSET);
>  }
>  

Re: [regression] Re: Linux 6.12.75

[Thorsten Leemhuis]

On 4/2/26 10:44, Vitaly Chikunov wrote:
> Sasha,
> 
> 1. I cannot find this commit posted on lore.kernel.org to report to
> exact patch.
> 
> | From: Matt Roper <matthew.d.roper@intel.com>
> | 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?

Ciao, Thorsten

Re: [regression] Re: Linux 6.12.75

[Vitaly Chikunov]

Thorsten, Sasha,

On Mon, Apr 13, 2026 at 01:33:18PM +0200, Thorsten Leemhuis wrote:
> On 4/2/26 10:44, Vitaly Chikunov wrote:
> > Sasha,
> > 
> > 1. I cannot find this commit posted on lore.kernel.org to report to
> > exact patch.
> > 
> > | From: Matt Roper <matthew.d.roper@intel.com>
> > | 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?

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

Re: [regression] Re: Linux 6.12.75

[Vitaly Chikunov]

Thorsten,

On Mon, Apr 13, 2026 at 05:17:30PM +0300, Vitaly Chikunov wrote:
> Thorsten, Sasha,
> 
> On Mon, Apr 13, 2026 at 01:33:18PM +0200, Thorsten Leemhuis wrote:
> > On 4/2/26 10:44, Vitaly Chikunov wrote:
> > > Sasha,
> > > 
> > > 1. I cannot find this commit posted on lore.kernel.org to report to
> > > exact patch.
> > > 
> > > | From: Matt Roper <matthew.d.roper@intel.com>
> > > | 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.

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

Re: [regression] Re: Linux 6.12.75

[Vitaly Chikunov]

Thorsten, Sasha,

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 <matthew.d.roper@intel.com>
> > > > | 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.

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

Re: [regression] Re: Linux 6.12.75

[Vitaly Chikunov]

Thorsten, Sasha,

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 <matthew.d.roper@intel.com>
> > > > > | 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")

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

Re: [regression] Re: Linux 6.12.75

[Vitaly Chikunov]

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 <matthew.d.roper@intel.com>
> > > > > > | 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