Messages in this thread |  | | From | Linus Torvalds <> | Date | Sat, 9 Jan 2021 17:37:09 -0800 | Subject | Re: [PATCH 0/1] mm: restore full accuracy in COW page reuse |
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On Sat, Jan 9, 2021 at 5:19 PM Linus Torvalds <torvalds@linux-foundation.org> wrote: > > And no, I didn't make the UFFDIO_WRITEPROTECT code take the mmap_sem > for writing. For whoever wants to look at that, it's > mwriteprotect_range() in mm/userfaultfd.c and the fix is literally to > turn the read-lock (and unlock) into a write-lock (and unlock).
Oh, and if it wasn't obvious, we'll have to debate what to do with trying to mprotect() a pinned page. Do we just ignore the pinned page (the way my clear_refs patch did)? Or do we turn it into -EBUSY? Or what?
So it's not *just* the locking that needs to be fixed. But just take a look at that suggested clear_refs patch of mine - it sure isn't complicated.
Linus
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