On 27 Mar 2026, at 9:37, David Hildenbrand (Arm) wrote: > On 3/27/26 02:42, Zi Yan wrote: >> collapse_file() requires FSes supporting large folio with at least >> PMD_ORDER, so replace the READ_ONLY_THP_FOR_FS check with that. shmem with >> huge option turned on also sets large folio order on mapping, so the check >> also applies to shmem. >> >> While at it, replace VM_BUG_ON with returning failure values. > > Why not VM_WARN_ON_ONCE() ? > > These are conditions that must be checked earlier, no?
start & (HPAGE_PMD_NR - 1) yes. I can convert it to VM_WARN_ON_ONCE(). For mapping_max_folio_order(mapping) < PMD_ORDER, I probably should move it to collapse_scan_file() to prevent wasting scanning time if the file does not support large folio. Then, I can turn it into a VM_WARN_ON_ONCE(). Best Regards, Yan, Zi
