From: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
filemap_create_folio() and do_read_cache_folio() were always allocating
folio of order 0. __filemap_get_folio was trying to allocate higher
order folios when fgp_flags had higher order hint set but it will default
to order 0 folio if higher order memory allocation fails.
As we bring the notion of mapping_min_order, make sure these functions
allocate at least folio of mapping_min_order as we need to guarantee it
in the page cache.
Add some additional VM_BUG_ON() in __filemap_add_folio to catch errors
where we add folios that has order less than min_order.
Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Acked-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
mm/filemap.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index 96fe5c7fe094..3e621c6344f7 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -849,6 +849,8 @@ noinline int __filemap_add_folio(struct address_space *mapping,
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
VM_BUG_ON_FOLIO(folio_test_swapbacked(folio), folio);
+ VM_BUG_ON_FOLIO(folio_order(folio) < mapping_min_folio_order(mapping),
+ folio);
mapping_set_update(&xas, mapping);
if (!huge) {
@@ -1886,8 +1888,10 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
folio_wait_stable(folio);
no_page:
if (!folio && (fgp_flags & FGP_CREAT)) {
- unsigned order = FGF_GET_ORDER(fgp_flags);
+ unsigned int min_order = mapping_min_folio_order(mapping);
+ unsigned int order = max(min_order, FGF_GET_ORDER(fgp_flags));
int err;
+ index = mapping_align_start_index(mapping, index);
if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping))
gfp |= __GFP_WRITE;
@@ -1912,8 +1916,11 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
gfp_t alloc_gfp = gfp;
err = -ENOMEM;
+ if (order < min_order)
+ order = min_order;
if (order > 0)
alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN;
+
folio = filemap_alloc_folio(alloc_gfp, order);
if (!folio)
continue;
@@ -1927,7 +1934,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
break;
folio_put(folio);
folio = NULL;
- } while (order-- > 0);
+ } while (order-- > min_order);
if (err == -EEXIST)
goto repeat;
@@ -2424,7 +2431,8 @@ static int filemap_create_folio(struct file *file,
unsigned int min_order = mapping_min_folio_order(mapping);
pgoff_t index;
- folio = filemap_alloc_folio(mapping_gfp_mask(mapping), 0);
+ folio = filemap_alloc_folio(mapping_gfp_mask(mapping),
+ min_order);
if (!folio)
return -ENOMEM;
@@ -3666,7 +3674,8 @@ static struct folio *do_read_cache_folio(struct address_space *mapping,
repeat:
folio = filemap_get_folio(mapping, index);
if (IS_ERR(folio)) {
- folio = filemap_alloc_folio(gfp, 0);
+ folio = filemap_alloc_folio(gfp,
+ mapping_min_folio_order(mapping));
if (!folio)
return ERR_PTR(-ENOMEM);
err = filemap_add_folio(mapping, folio, index, gfp);
--
2.43.0
