On Thu, Jun 03, 2021 at 11:32:16AM -0700, Axel Rasmussen wrote: [...] Not a native speaker, feel free to take anything I said with a grain of salt.. > @@ -278,14 +287,8 @@ by the current kernel version. > (Since Linux 4.3.) > Register a memory address range with the userfaultfd object. > The pages in the range must be "compatible". > -.PP > -Up to Linux kernel 4.11, > -only private anonymous ranges are compatible for registering with > -.BR UFFDIO_REGISTER . > -.PP > -Since Linux 4.11, > -hugetlbfs and shared memory ranges are also compatible with > -.BR UFFDIO_REGISTER . > +What constitutes "compatible" depends on the mode(s) being used, as described > +below. Would below be slightly better? Please refer to the list of register modes below for the compatible memory backends for each mode. [...] > @@ -735,6 +745,109 @@ or not registered with userfaultfd write-protect mode. > .TP > .B EFAULT > Encountered a generic fault during processing. > +.\" > +.SS UFFDIO_CONTINUE > +(Since Linux 5.13.) > +Used for resolving minor faults specifically. > +Take the existing page(s) in the range registered with > +.B UFFDIO_REGISTER_MODE_MINOR > +and install page table entries for them. "Take the existing page" reads a bit weird to me. How about something like: "Resolving minor-mode trapped page faults by installing page table entries with pages in the page cache"? [...] > +.TP > +.B EINVAL > +An invalid bit was specified in the > +.IR mode > +field. > +.TP > +.B EEXIST > +One or more pages were already mapped in the given range. I'd think this sentence is good enough; slightly prefer dropping the latter one "In other words..." below, as "mapped" should mean the same to me (and the wording "fully mapped" is a bit confusing too..). > +In other words, not only did pages exist in the page cache, but page table > +entries already existed for those pages and they were fully mapped. [...] Thanks, -- Peter Xu
