On Fri, May 31, 2019 at 7:52 AM Ira Weiny <ira.weiny@xxxxxxxxx> wrote: > > On Thu, May 30, 2019 at 04:21:19PM -0700, John Hubbard wrote: > > On 5/30/19 2:47 PM, Ira Weiny wrote: > > > On Thu, May 30, 2019 at 06:54:04AM +0800, Pingfan Liu wrote: > > [...] > > >> + for (j = i; j < nr; j++) > > >> + put_page(pages[j]); > > > > > > Should be put_user_page() now. For now that just calls put_page() but it is > > > slated to change soon. > > > > > > I also wonder if this would be more efficient as a check as we are walking the > > > page tables and bail early. > > > > > > Perhaps the code complexity is not worth it? > > > > Good point, it might be worth it. Because now we've got two loops that > > we run, after the interrupts-off page walk, and it's starting to look like > > a potential performance concern. > > FWIW I don't see this being a huge issue at the moment. Perhaps those more > familiar with CMA can weigh in here. How was this issue found? If it was > found by running some test perhaps that indicates a performance preference? > I found the bug by reading code. And I do not see any performance concern. Bailing out early contritute little to performance, as we fall on the slow path immediately. Regards, Pingfan [....]
