| Message ID | d6f8e4451910da1de0420eb82724dd85c368741c.1724054125.git.baolin.wang@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | support shmem mTHP collapse | expand |
On 19.08.24 10:14, Baolin Wang wrote: > Expand the is_refcount_suitable() to support reference checks for file folios, > as preparation for supporting shmem mTHP collapse. > > Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> > --- > mm/khugepaged.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index cdd1d8655a76..f11b4f172e61 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -549,8 +549,14 @@ static bool is_refcount_suitable(struct folio *folio) > int expected_refcount; > > expected_refcount = folio_mapcount(folio); > - if (folio_test_swapcache(folio)) > + if (folio_test_anon(folio)) { > + expected_refcount += folio_test_swapcache(folio) ? > + folio_nr_pages(folio) : 0; > + } else { > expected_refcount += folio_nr_pages(folio); > + if (folio_test_private(folio)) > + expected_refcount++; > + } Alternatively, a bit neater if (!folio_test_anon(folio) || folio_test_swapcache(folio)) expected_refcount += folio_nr_pages(folio); if (folio_test_private(folio)) expected_refcount++; The latter check should be fine even for anon folios (although always false) > > return folio_ref_count(folio) == expected_refcount; > } > @@ -2285,8 +2291,7 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr, > break; > } > > - if (folio_ref_count(folio) != > - 1 + folio_mapcount(folio) + folio_test_private(folio)) { The "1" is due to the pagecache, right? IIUC, we don't hold a raised folio refcount as we do the xas_for_each().
On 2024/8/19 16:36, David Hildenbrand wrote: > On 19.08.24 10:14, Baolin Wang wrote: >> Expand the is_refcount_suitable() to support reference checks for file >> folios, >> as preparation for supporting shmem mTHP collapse. >> >> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> >> --- >> mm/khugepaged.c | 11 ++++++++--- >> 1 file changed, 8 insertions(+), 3 deletions(-) >> >> diff --git a/mm/khugepaged.c b/mm/khugepaged.c >> index cdd1d8655a76..f11b4f172e61 100644 >> --- a/mm/khugepaged.c >> +++ b/mm/khugepaged.c >> @@ -549,8 +549,14 @@ static bool is_refcount_suitable(struct folio >> *folio) >> int expected_refcount; >> expected_refcount = folio_mapcount(folio); >> - if (folio_test_swapcache(folio)) >> + if (folio_test_anon(folio)) { >> + expected_refcount += folio_test_swapcache(folio) ? >> + folio_nr_pages(folio) : 0; >> + } else { >> expected_refcount += folio_nr_pages(folio); >> + if (folio_test_private(folio)) >> + expected_refcount++; >> + } > > Alternatively, a bit neater > > if (!folio_test_anon(folio) || folio_test_swapcache(folio)) > expected_refcount += folio_nr_pages(folio); > if (folio_test_private(folio)) > expected_refcount++; > > The latter check should be fine even for anon folios (although always > false) Looks better. Will do in v2. >> return folio_ref_count(folio) == expected_refcount; >> } >> @@ -2285,8 +2291,7 @@ static int hpage_collapse_scan_file(struct >> mm_struct *mm, unsigned long addr, >> break; >> } >> - if (folio_ref_count(folio) != >> - 1 + folio_mapcount(folio) + folio_test_private(folio)) { > > The "1" is due to the pagecache, right? IIUC, we don't hold a raised > folio refcount as we do the xas_for_each(). Right.
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index cdd1d8655a76..f11b4f172e61 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -549,8 +549,14 @@ static bool is_refcount_suitable(struct folio *folio) int expected_refcount; expected_refcount = folio_mapcount(folio); - if (folio_test_swapcache(folio)) + if (folio_test_anon(folio)) { + expected_refcount += folio_test_swapcache(folio) ? + folio_nr_pages(folio) : 0; + } else { expected_refcount += folio_nr_pages(folio); + if (folio_test_private(folio)) + expected_refcount++; + } return folio_ref_count(folio) == expected_refcount; } @@ -2285,8 +2291,7 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr, break; } - if (folio_ref_count(folio) != - 1 + folio_mapcount(folio) + folio_test_private(folio)) { + if (!is_refcount_suitable(folio)) { result = SCAN_PAGE_COUNT; break; }
Expand the is_refcount_suitable() to support reference checks for file folios, as preparation for supporting shmem mTHP collapse. Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> --- mm/khugepaged.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)