On Thu, Mar 02, 2023 at 06:54:23PM +0100, David Hildenbrand wrote: > Currently, we'd lose the userfaultfd-wp marker when PTE-mapping a huge > zeropage, resulting in the next write faults in the PMD range > not triggering uffd-wp events. > > Various actions (partial MADV_DONTNEED, partial mremap, partial munmap, > partial mprotect) could trigger this. However, most importantly, > un-protecting a single sub-page from the userfaultfd-wp handler when > processing a uffd-wp event will PTE-map the shared huge zeropage and > lose the uffd-wp bit for the remainder of the PMD. > > Let's properly propagate the uffd-wp bit to the PMDs. Ouch.. I thought this was reported once, probably it fell through the cracks. Acked-by: Peter Xu <peterx@xxxxxxxxxx> Thanks, -- Peter Xu
