Re: [PATCH 1/3] mm/hugetlb: Fix race condition of uffd missing/minor handling

[Nadav Amit]

On Oct 3, 2022, at 2:16 PM, Peter Xu <peterx@xxxxxxxxxx> wrote:

> On Mon, Oct 03, 2022 at 02:00:36PM -0700, Nadav Amit wrote:
>> On Oct 3, 2022, at 8:56 AM, Peter Xu <peterx@xxxxxxxxxx> wrote:
>> 
>>> +			 */
>>> +			if (hugetlb_pte_stable(h, mm, ptep, old_pte))
>>> +				ret = hugetlb_handle_userfault(
>>> +				    vma, mapping, idx, flags, haddr,
>>> +				    address, VM_UFFD_MISSING);
>>> +			else
>>> +				/* Retry the fault */
>>> +				ret = 0;
>> 
>> Might be unrelated, but at least for the sake of consistency if not
>> potential GUP issues, don’t you want to return VM_FAULT_RETRY ?
> 
> VM_FAULT_RETRY implies releasing of mmap sem, while we didn't?

Of course. My bad.