On 26.08.24 01:25, Hugh Dickins wrote:
Although shmem_get_folio_gfp() is correctly putting inodes on the
shrinklist according to the folio size, shmem_unused_huge_shrink()
was still dealing with that shrinklist in terms of HPAGE_PMD_SIZE.
Generalize that; and to handle the mixture of sizes more sensibly,
shmem_alloc_and_add_folio() give it a number of pages to be freed
(approximate: no need to minimize that with an exact calculation)
instead of a number of inodes to split.
That might be worth a comment in the code.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
---
This patch would most naturally go into mm-unstable as 10/9 over
Baolin's "support large folio swap-out and swap-in for shmem" series.
mm/shmem.c | 45 ++++++++++++++++++++-------------------------
1 file changed, 20 insertions(+), 25 deletions(-)
diff --git a/mm/shmem.c b/mm/shmem.c
index 4dd0570962fa..4c9921c234b7 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -636,15 +636,14 @@ static const char *shmem_format_huge(int huge)
#endif
static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
- struct shrink_control *sc, unsigned long nr_to_split)
+ struct shrink_control *sc, unsigned long nr_to_free)
{
LIST_HEAD(list), *pos, *next;
- LIST_HEAD(to_remove);
struct inode *inode;
struct shmem_inode_info *info;
struct folio *folio;
unsigned long batch = sc ? sc->nr_to_scan : 128;
- int split = 0;
+ unsigned long split = 0, freed = 0;
if (list_empty(&sbinfo->shrinklist))
return SHRINK_STOP;
@@ -662,13 +661,6 @@ static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
goto next;
}
- /* Check if there's anything to gain */
- if (round_up(inode->i_size, PAGE_SIZE) ==
- round_up(inode->i_size, HPAGE_PMD_SIZE)) {
- list_move(&info->shrinklist, &to_remove);
- goto next;
- }
-
list_move(&info->shrinklist, &list);
next:
sbinfo->shrinklist_len--;
@@ -677,34 +669,36 @@ static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
}
spin_unlock(&sbinfo->shrinklist_lock);
- list_for_each_safe(pos, next, &to_remove) {
- info = list_entry(pos, struct shmem_inode_info, shrinklist);
- inode = &info->vfs_inode;
- list_del_init(&info->shrinklist);
- iput(inode);
- }
-
list_for_each_safe(pos, next, &list) {
+ pgoff_t next, end;
+ loff_t i_size;
int ret;
- pgoff_t index;
info = list_entry(pos, struct shmem_inode_info, shrinklist);
inode = &info->vfs_inode;
- if (nr_to_split && split >= nr_to_split)
+ if (nr_to_free && freed >= nr_to_free)
goto move_back;
- index = (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT;
- folio = filemap_get_folio(inode->i_mapping, index);
- if (IS_ERR(folio))
+ i_size = i_size_read(inode);
+ folio = filemap_get_entry(inode->i_mapping, i_size / PAGE_SIZE);
+ if (!folio || xa_is_value(folio))
goto drop;
- /* No huge page at the end of the file: nothing to split */
+ /* No large page at the end of the file: nothing to split */
s/large page/large folio/
Or simply "Nothing to split."
if (!folio_test_large(folio)) {
folio_put(folio);
goto drop;
}
+ /* Check if there is anything to gain from splitting */
+ next = folio_next_index(folio);
+ end = shmem_fallocend(inode, DIV_ROUND_UP(i_size, PAGE_SIZE));
+ if (end <= folio->index || end >= next) {
+ folio_put(folio);
+ goto drop;
+ }
+
Looks sensible to me
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
--
Cheers,
David / dhildenb
