On Tue, Nov 20, 2018 at 02:43:23PM +0100, Michal Hocko wrote: > From: Michal Hocko <mhocko@xxxxxxxx> > > filemap_map_pages takes a speculative reference to each page in the > range before it tries to lock that page. While this is correct it > also can influence page migration which will bail out when seeing > an elevated reference count. The faultaround code would bail on > seeing a locked page so we can pro-actively check the PageLocked > bit before page_cache_get_speculative and prevent from pointless > reference count churn. Looks fine to me. But please drop a line of comment in the code. As is it might be confusing for a reader. -- Kirill A. Shutemov
