Messages in this thread | | | From | Linus Torvalds <> | Date | Thu, 7 Jan 2021 12:32:09 -0800 | Subject | Re: [PATCH 0/2] page_count can't be used to decide when wp_page_copy |
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On Thu, Jan 7, 2021 at 12:25 PM Jason Gunthorpe <jgg@ziepe.ca> wrote: > > Lots of places are relying on pin_user_pages long term pins of memory, > and cannot be converted to notifiers. > > I don't think it is reasonable to just declare that insecure and > requires privileges, it is a huge ABI break.
Also, I think GUP (and pin_user_pages() as a special case) is a lot more important and more commonly used than UFFD.
Which is really why I think this needs to be fixed by just fixing UFFD to take the write lock.
I think Andrea is blinded by his own love for UFFDIO: when I do a debian codesearch for UFFDIO_WRITEPROTECT, all it finds is the kernel and strace (and the qemu copies of the kernel headers).
Does the debian code search cover everything? Obviously not. But if you cannot find A SINGLE USE of that thing in the Debian code search, then that is sure a sign of _something_.
Linus
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