On 18.12.21 03:42, Linus Torvalds wrote:
On Fri, Dec 17, 2021 at 6:17 PM Linus Torvalds torvalds@linux-foundation.org wrote:
I think the hugepage code should use the exact same logic that the regular wp fault code does.
IOW, I think that this stupid (AND UNTESTED) patch should likely just fix David's test-case with the hugepage and splice thing..
Or at least be somewhat close. But it should be paired with the GUP side doing the right thing too, of course. Maybe it already does, maybe it doesn't, I didn't check...
And maybe there's something subtle about the page_count() of a THP entry. Again, I can't really claim to have tested this all, but I'm hoping this makes somebody go "Ahh, now I see what Linus means"
Not the reaction you are hoping for: "Gah, Linus still doesn't see why the page_count is just wrong". :)
See the mail I just wrote, let's get a common understanding of how our check should actually look like.