On Mon, Oct 30, 2023 at 07:41:23PM -0400, Gregory Price wrote: > On Mon, Oct 30, 2023 at 11:22:18PM +0000, Matthew Wilcox wrote: > > On Mon, Oct 30, 2023 at 02:00:05PM -0400, Gregory Price wrote: > > > kpageflags reads page-flags directly from the page, even when the > > > respective flag is only updated on the headpage of a folio. > > > > > > Update bitchecks to use PAGEFLAG() interfaces to check folio for the > > > referenced, dirty, lru, active, and unevictable bits. > > > > But uptodate, writeback and reclaim (amongst others) are also defined > > only on the head page. > > > > Ah yes i was only looking at the things defined w/ PAGEFLAG defines in > page-flags.h. I'll give it full once over can collect them all, my bad. > > (also i forgot to update my commit message) > > Quick question here since i have your attention: any recommendation on > what to do for ONLY_HEAD flags? If the provided page is not the head, > should the flag report 0... or whatever the head says? Thinking about it some more, really almost all flags are per-folio, not per-page. The only exceptions are HWPoison and AnonExclusive. So probably the right way to do this is to make k = folio->flags, and then just change a few places rather than changing all the places that test 'k'.
