Re: [PATCH v2 0/3] hold PTL for several .hugetlb_entry callbacks

[Jinjiang Tu <tujinjiang@huawei.com>]

在 2025/7/25 0:26, David Hildenbrand 写道:
> On 24.07.25 11:09, Jinjiang Tu wrote:
>> Changelog since v1:
>>   * update the subject pacth #1
>>   * add patch #2 and #3 to hold PTL for some other .hugetlb_entry 
>> callbacks
>>
>> Patch #1 fixes a race between smaps_hugetlb_range() and migration by 
>> holding
>> PTL in smaps_hugetlb_range().
>>
>> To avoid operating on stale pages, add PTL for several .hugetlb_entry
>> callbacks too. We don't hold PTL in __s390_enable_skey_hugetlb() and
>> prot_none_hugetlb_entry(), since the mmap write lock is held.
>
> There could be rmap walkers only holding the rmap lock (but I recall 
> that s390x does not support migration of hugetlb folios, not sure).
>
> In any, case, ok to leave that alone for now.
>
> We don't
>> hold PTL in hwpoison_hugetlb_range() too, since it only reads the pte 
>> and
>> doesn't operate the page.
>
> Not sure ... we should just handle it like the PTE/PMD case and not 
> play any tricks.
>
Indeed, I will update hwpoison_hugetlb_range() too.