Re: [PATCH] mm/memfd: clear hugetlb pages on allocation

[Deepanshu Kartikey]

Hi Oscar and David,

Thanks for the guidance!

> I guess it is worth looking into it, I shall fiddle with it.

Great, I'll focus on fixing the immediate bugs in v2 and you can handle
the refactoring in a follow-up. This keeps my patch focused on the
security fix + the missing initialization steps.

> Yes, I would go with folio_zero_user() as well, to match what we do in
> all paths.

Understood. I'll use folio_zero_user() in v2.

So for v2, I'll add:
1. folio_zero_user() instead of folio_zero_range()
2. folio_mark_uptodate()
3. hugetlb_fault_mutex locking around hugetlb_add_to_page_cache()

This will match the pattern in hugetlb_no_page() and fix the information
leak, missing uptodate flag, and locking issue.

I'll send v2 shortly after testing.

Thanks,
Deepanshu