On 11/02/2025 00:30, Nico Pache wrote: > alloc_charge_folio allocates the new folio for the khugepaged collapse. > Generalize the order of the folio allocations to support future mTHP > collapsing. > > No functional changes in this patch. > > Signed-off-by: Nico Pache <[email protected]> > --- > mm/khugepaged.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index c834ea842847..0cfcdc11cabd 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1074,14 +1074,14 @@ static int __collapse_huge_page_swapin(struct > mm_struct *mm, > } > > static int alloc_charge_folio(struct folio **foliop, struct mm_struct *mm, > - struct collapse_control *cc) > + struct collapse_control *cc, int order) > { > gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() : > GFP_TRANSHUGE); > int node = khugepaged_find_target_node(cc); > struct folio *folio; > > - folio = __folio_alloc(gfp, HPAGE_PMD_ORDER, node, &cc->alloc_nmask); > + folio = __folio_alloc(gfp, order, node, &cc->alloc_nmask); > if (!folio) { > *foliop = NULL; > count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
Stats management is different for PMD-sized THP vs mTHP. All the PMD-sized THP stats continue to be accumulated in /proc/meminfo (or whatever its called). Other THP sizes are not accounted here. All mTHP sizes (*including* PMD-sized) should accounted in /sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/stats/*. There is a file for each stat. We decided to do it this way for fear of breaking unenlightened user space that only understands PMD-sized THP. You can find the mTHP stats machinery at count_mthp_stat(). > @@ -1125,7 +1125,7 @@ static int collapse_huge_page(struct mm_struct *mm, > unsigned long address, > */ > mmap_read_unlock(mm); > > - result = alloc_charge_folio(&folio, mm, cc); > + result = alloc_charge_folio(&folio, mm, cc, HPAGE_PMD_ORDER); > if (result != SCAN_SUCCEED) > goto out_nolock; > > @@ -1851,7 +1851,7 @@ static int collapse_file(struct mm_struct *mm, unsigned > long addr, > VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); > VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); > > - result = alloc_charge_folio(&new_folio, mm, cc); > + result = alloc_charge_folio(&new_folio, mm, cc, HPAGE_PMD_ORDER); > if (result != SCAN_SUCCEED) > goto out; >
