On 4/28/26 22:17, Zi Yan wrote: > On 28 Apr 2026, at 16:07, David Hildenbrand (Arm) wrote: > >> On 4/28/26 21:56, Zi Yan wrote: >>> >>> >>> This patch breaks the khugepaged test for READ_ONLY_THP_FOR_FS. >>> >>> When I ran sudo ./khugepaged all:file ~/ on ext4, >>> >>> collapse_max_ptes_none (khugepaged:file) fails. >> >> madvise() still works? Is it maybe because of dirty folios? (but that should >> also be the case on write ...) > > I asked codex instead. > > Basically, mmap(MMAP_SHARED) makes the written folio dirty and the folio > survives the later drop_caches. Adding msync() fixes the issue.
But why doesn't the write() make the folios dirty? Or are we running into some race condition where the old code just worked by chance? -- Cheers, David
