On Thu, Aug 20, 2026 at 07:37:29PM -0400, Zi Yan wrote: > On Thu Aug 20, 2026 at 5:23 PM EDT, Yeoreum Yun wrote: > > On Thu, Aug 20, 2026 at 03:51:34PM -0400, Zi Yan wrote: > >> On Thu Aug 20, 2026 at 3:40 PM EDT, Yeoreum Yun wrote: > >> > There're some random failure for split_huge_page_test when khugepaged > >> > collapses pages into pmd again which had split by the test. > >> > > >> > Prevent the khugepaged's collapses for split page by setting the > >> > mapped pmd-huge-page with MADV_NOHUGEPAGE before split. > >> > >> Why not disable khugepaged using APIs from hugepage_setting.h? > > > > Well, this also works with hugepage_save_settings() and write the > > khugepaged/scan_sleep_millisecs with the maximum integer. > > > > I don't have a strong opinion but since it seems more hackish way to > > change scan_sllep_millisecs, I use madvise() with MADV_NOHUGEPATE. > > > > Would it be better to change using APIs in hugepage_setting,h? > > No. I did not realize there is no way of stopping khugepaged completely. > > BTW, I am curious about your khugepaged config causing this issue. > IIRC, khugepaged scan interval is about minutes and > the time between madvise(MADV_HUGEPAGE) and the second > is_backed_by_folio() should not be that long.
Yes. it's relly timing sensitive and I've failed to reproduce in the real hardware. but in the emulation environment it often failed with the scan_sllep_millisecs as 10 seconds while the test running. > > For your patch, maybe you want to check the return value of madvise() to > make sure it succeeds. Yeap. but it seems enough just worning message for the madvise() with MADV_NOHUGEPAGE. > > Otherwise, > > feel free to add > > Reviewed-by: Zi Yan <[email protected]> Thanks! -- Sincerely, Yeoreum Yun
