Re: [git pull] drm for 6.13-rc1

[AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>]

Il 06/12/24 09:54, CK Hu (胡俊光) ha scritto:
> Hi, Sasha:
> 
> On Mon, 2024-11-25 at 01:35 +0100, Javier Carrasco wrote:
>> External email : Please do not click links or open attachments until you have verified the sender or the content.
>>
>>
>> On 24/11/2024 23:58, Dave Airlie wrote:
>>> On Mon, 25 Nov 2024 at 02:41, Sasha Levin <sashal@kernel.org> wrote:
>>>>
>>>> On Thu, Nov 21, 2024 at 10:25:45AM +1000, Dave Airlie wrote:
>>>>> Hi Linus,
>>>>>
>>>>> This is the main drm pull request for 6.13.
>>>>>
>>>>> I've done a test merge into your tree, there were two conflicts both
>>>>> of which seem easy enough to resolve for you.
>>>>>
>>>>> There's a lot of rework, the panic helper support is being added to
>>>>> more drivers, v3d gets support for HW superpages, scheduler
>>>>> documentation, drm client and video aperture reworks, some new
>>>>> MAINTAINERS added, amdgpu has the usual lots of IP refactors, Intel
>>>>> has some Pantherlake enablement and xe is getting some SRIOV bits, but
>>>>> just lots of stuff everywhere.
>>>>>
>>>>> Let me know if there are any issues,
>>>>
>>>> Hey Dave,
>>>>
>>>> After the PR was merged, I've started seeing boot failures reported by
>>>> KernelCI:
>>>
>>> I'll add the mediatek names I see who touched anything in the area recently.
>>>
>>> Dave.
>>>>
>>>> [    4.395400] mediatek-drm mediatek-drm.5.auto: bound 1c014000.merge (ops 0xffffd35fd12975f8)
>>>> [    4.396155] mediatek-drm mediatek-drm.5.auto: bound 1c000000.ovl (ops 0xffffd35fd12977b8)
>>>> [    4.411951] mediatek-drm mediatek-drm.5.auto: bound 1c002000.rdma (ops 0xffffd35fd12989c0)
>>>> [    4.536837] mediatek-drm mediatek-drm.5.auto: bound 1c004000.ccorr (ops 0xffffd35fd1296cf0)
>>>> [    4.545181] mediatek-drm mediatek-drm.5.auto: bound 1c005000.aal (ops 0xffffd35fd1296a80)
>>>> [    4.553344] mediatek-drm mediatek-drm.5.auto: bound 1c006000.gamma (ops 0xffffd35fd12972b0)
>>>> [    4.561680] mediatek-drm mediatek-drm.5.auto: bound 1c014000.merge (ops 0xffffd35fd12975f8)
>>>> [    4.570025] ------------[ cut here ]------------
>>>> [    4.574630] refcount_t: underflow; use-after-free.
>>>> [    4.579416] WARNING: CPU: 6 PID: 81 at lib/refcount.c:28 refcount_warn_saturate+0xf4/0x148
>>>> [    4.587670] Modules linked in:
>>>> [    4.590714] CPU: 6 UID: 0 PID: 81 Comm: kworker/u32:3 Tainted: G        W          6.12.0 #1 cab58e2e59020ebd4be8ada89a65f465a316c742
>>>> [    4.602695] Tainted: [W]=WARN
>>>> [    4.605649] Hardware name: Acer Tomato (rev2) board (DT)
>>>> [    4.610947] Workqueue: events_unbound deferred_probe_work_func
>>>> [    4.616768] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>>>> [    4.623715] pc : refcount_warn_saturate+0xf4/0x148
>>>> [    4.628493] lr : refcount_warn_saturate+0xf4/0x148
>>>> [    4.633270] sp : ffff8000807639c0
>>>> [    4.636571] x29: ffff8000807639c0 x28: ffff34ff4116c640 x27: ffff34ff4368e080
>>>> [    4.643693] x26: ffffd35fd1299ac8 x25: ffff34ff46c8c410 x24: 0000000000000000
>>>> [    4.650814] x23: ffff34ff4368e080 x22: 00000000fffffdfb x21: 0000000000000002
>>>> [    4.657934] x20: ffff34ff470c6000 x19: ffff34ff410c7c10 x18: 0000000000000006
>>>> [    4.665055] x17: 666678302073706f x16: 2820656772656d2e x15: ffff800080763440
>>>> [    4.672176] x14: 0000000000000000 x13: 2e656572662d7265 x12: ffffd35fd2ed14f0
>>>> [    4.679297] x11: 0000000000000001 x10: 0000000000000001 x9 : ffffd35fd0342150
>>>> [    4.686418] x8 : c0000000ffffdfff x7 : ffffd35fd2e21450 x6 : 00000000000affa8
>>>> [    4.693539] x5 : ffffd35fd2ed1498 x4 : 0000000000000000 x3 : 0000000000000000
>>>> [    4.700660] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff34ff40932580
>>>> [    4.707781] Call trace:
>>>> [    4.710216]  refcount_warn_saturate+0xf4/0x148 (P)
>>>> [    4.714993]  refcount_warn_saturate+0xf4/0x148 (L)
>>>> [    4.719772]  kobject_put+0x110/0x118
>>>> [    4.723335]  put_device+0x1c/0x38
>>>> [    4.726638]  mtk_drm_bind+0x294/0x5c0
>>>> [    4.730289]  try_to_bring_up_aggregate_device+0x16c/0x1e0
>>>> [    4.735673]  __component_add+0xbc/0x1c0
>>>> [    4.739495]  component_add+0x1c/0x30
>>>> [    4.743058]  mtk_disp_rdma_probe+0x140/0x210
>>>> [    4.747314]  platform_probe+0x70/0xd0
>>>> [    4.750964]  really_probe+0xc4/0x2a8
>>>> [    4.754527]  __driver_probe_device+0x80/0x140
>>>> [    4.758870]  driver_probe_device+0x44/0x120
>>>> [    4.763040]  __device_attach_driver+0xc0/0x108
>>>> [    4.767470]  bus_for_each_drv+0x8c/0xf0
>>>> [    4.771294]  __device_attach+0xa4/0x198
>>>> [    4.775117]  device_initial_probe+0x1c/0x30
>>>> [    4.779286]  bus_probe_device+0xb4/0xc0
>>>> [    4.783109]  deferred_probe_work_func+0xb0/0x100
>>>> [    4.787714]  process_one_work+0x18c/0x420
>>>> [    4.791712]  worker_thread+0x30c/0x418
>>>> [    4.795449]  kthread+0x128/0x138
>>>> [    4.798665]  ret_from_fork+0x10/0x20
>>>> [    4.802229] ---[ end trace 0000000000000000 ]---
>>>>
>>>> I don't think that I'll be able to bisect further as I don't have the
>>>> relevant hardware available.
>>>>
>>>> --
>>>> Thanks,
>>>> Sasha
>>
>>
>> Hello, I am one of those who touched something in the area.
>>
>> To check if my changes are the cause of the boot failures, please apply
>> this patch:
>>
>> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
>> b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
>> index 9a8ef8558da9..85be035a209a 100644
>> --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
>> +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
>> @@ -373,11 +373,12 @@ static bool mtk_drm_get_all_drm_priv(struct device
>> *dev)
>>          struct mtk_drm_private *temp_drm_priv;
>>          struct device_node *phandle = dev->parent->of_node;
>>          const struct of_device_id *of_id;
>> +       struct device_node *node;
>>          struct device *drm_dev;
>>          unsigned int cnt = 0;
>>          int i, j;
>>
>> -       for_each_child_of_node_scoped(phandle->parent, node) {
>> +       for_each_child_of_node(phandle->parent, node) {
>>                  struct platform_device *pdev;
>>
>>                  of_id = of_match_node(mtk_drm_of_ids, node);
>>
> 
> Does Javier's patch fix the problem?
> 

CK, to resolve the issue, please revert commit

fd620fc25d88 ("drm/mediatek: Switch to for_each_child_of_node_scoped()")

Thanks,
Angelo

> Regards,
> CK
> 
>>
>> ---
>>
>>
>> This chunk can be found in mtk_drm_get_all_drm_priv(), which is not
>> listed in the trace, but it is called from mtk_drm_bind().
>>
>> The loop did not release the child_node if cnt == MAX_CRTC (by means of
>> a break), which goes against how for_each_child_of_node() should be
>> handled. If the child_node is indeed required afterwards (it is not
>> referenced anywhere after the loop), it should be acquired via
>> of_node_get() and stored somewhere to be able to put it later.
>>
>> Then another issue would lie underneath as the reference to the
>> child_node is not stored in any way. But if this patch fixes the issue,
>> then I suppose it should be applied immediately, and the rest should be
>> discussed later on.
>>
>> By the way, are there any logs with debug/error messages to analyze
>> further is the issue is something different?
>>
>> Thanks and best regards,
>> Javier Carrasco
>