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Shutemov" , Yang Shi , Paul Mackerras , Ben Skeggs , Andrew Morton Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Oct 12, 2020 at 10:46 AM Ralph Campbell wrote: > > ZONE_DEVICE struct pages have an extra reference count that complicates the > code for put_page() and several places in the kernel that need to check the > reference count to see that a page is not being used (gup, compaction, > migration, etc.). Clean up the code so the reference count doesn't need to > be treated specially for device private pages, leaving DAX as still being > a special case. Please no half-step to removing the special casing... [..] > +void free_zone_device_page(struct page *page) > +{ > + if (!is_device_private_page(page)) > return; That seems too subtle to be acceptable to me. All ZONE_DEVICE pages need to have the same relationship with respect to idle-ness and the page reference count.