Re: [PATCH v5 mm-new 0/6] mm: hugetlb: allocate frozen gigantic folio

[Zi Yan <ziy@nvidia.com>]

On 7 Jan 2026, at 20:53, Kefeng Wang wrote:

> On 2026/1/8 9:05, Kefeng Wang wrote:
>>
>>
>> On 2026/1/8 3:38, Zi Yan wrote:
>>> On 7 Jan 2026, at 13:39, Mark Brown wrote:
>>>
>>>> On Wed, Jan 07, 2026 at 07:31:30PM +0200, Claudiu Beznea wrote:
>>>>> On 12/30/25 09:24, Kefeng Wang wrote:
>>>>
>>>>>> Introduce alloc_contig_frozen_pages() and cma_alloc_frozen_compound()
>>>>>> which avoid atomic operation about page refcount, and then convert to
>>>>>> allocate frozen gigantic folio by the new helpers in hugetlb to cleanup
>>>>>> the alloc_gigantic_folio().
>>>>>
>>>>> I'm seeing the following issues on the Renesas RZ/G3S SoC when doing suspend
>>>>> to idle:
>>>>>
>>>>> [  129.636729] Unable to handle kernel paging request at virtual address
>>>>> dead000000000108
>>>>> [  129.644674] Mem abort info:
>>>>> [  129.647456]   ESR = 0x0000000096000044
>>>>
>>>> This is also introducing OOMs when doing at least audio tests (I don't
>>>> think these are super relevant) on Raspberry Pi 3B+ running NFS root
>>>> (probably more relevant):
>>>>
>>>> [   64.064256] Unable to handle kernel paging request at virtual address fffffdffc1000000
>>>>
>>>> ...
>>>>
>>>> [   64.087583] Call trace:
>>>> [   64.087586]  kmem_cache_free+0x88/0x434 (P)
>>>> [   64.087598]  skb_free_head+0x9c/0xb8
>>>> [   64.087608]  skb_release_data+0x120/0x174
>>>> [   64.087615]  __kfree_skb+0x2c/0x44
>>>> [   64.087622]  tcp_data_queue+0x948/0xe50
>>>>
>>>> Full log:
>>>>
>>>>    https://lava.sirena.org.uk/scheduler/job/2341856#L1721
>>>>
>>>> Bisection identifies:
>>>>
>>>> [fb9a328d30400dbc8b2ea5a57daeb28bedac398b] mm: cma: add cma_alloc_frozen{_compound}()
>>>>
>>>> as being the comit that introduces the issue.  Bisect log with links to
>>>> further test runs:
>>>
>>> Hi Mark and Claudiu,
>>
>> Thanks for the reports.
>>
>>>
>>> Can you try the patch below to see if it fixes the issue? Basically,
>>> in cma_release(), count was used to drop page ref and decreased to 0,
>>> but after the loop, count becomes -1 and __cma_release_frozen()
>>> is releasing unnecessary pages.
>>
>> Oh，sorry for introducing the regression, my previous self-tests were
>> more focused on the hugetlb part, I should be more careful about this,
>> and thanks Zi Yan for the quick fix, I will do more check and test for
>> the non-hugetlb part.
>>
>>
>
> Based on the cma_debug interface, I performed quick tests to reproduce
> the issue before Zi's fix. With the fix applied, the crash was resolved,
> and no other issues were observed during testing.

It seems that the series is dropped from Andrew’s tree. You probably want
to send a new version with the fix folded.

Best Regards,
Yan, Zi