diff options
| author | Zi Yan <ziy@nvidia.com> | 2026-05-17 09:54:08 -0400 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-05-28 21:31:38 -0700 |
| commit | 0e68ac2c8791d0f411e6b090f663fed7970640d9 (patch) | |
| tree | 69ffa11e737c644359c0120d73cab6b70af5ee7b /mm | |
| parent | bb82860db5c4d2a2761e805dc31ce61719784c74 (diff) | |
| download | linux-next-history-0e68ac2c8791d0f411e6b090f663fed7970640d9.tar.gz | |
mm: fs: remove filemap_nr_thps*() functions and their users
They are used by READ_ONLY_THP_FOR_FS to handle writes to FSes without
large folio support, so that read-only THPs created in these FSes are not
seen by the FSes when the underlying fd becomes writable. Now read-only
PMD THPs only appear in a FS with large folio support and the supported
orders include PMD_ORDER.
READ_ONLY_THP_FOR_FS was using mapping->nr_thps, inode->i_writecount, and
smp_mb() to prevent writes to a read-only THP and collapsing writable
folios into a THP. In collapse_file(), mapping->nr_thps is increased,
then smp_mb(), and if inode->i_writecount > 0, collapse is stopped, while
do_dentry_open() first increases inode->i_writecount, then a full memory
fence, and if mapping->nr_thps > 0, all read-only THPs are truncated.
Now this mechanism can be removed along with READ_ONLY_THP_FOR_FS code,
since a dirty folio check has been added after try_to_unmap() in
collapse_file() to prevent dirty folios from being collapsed as clean.
Link: https://lore.kernel.org/20260517135416.1434539-7-ziy@nvidia.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Mason <clm@fb.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Sterba <dsterba@suse.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/filemap.c | 1 | ||||
| -rw-r--r-- | mm/huge_memory.c | 1 | ||||
| -rw-r--r-- | mm/khugepaged.c | 28 |
3 files changed, 0 insertions, 30 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index 4263d97759985..5aaba0d3e81d6 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -189,7 +189,6 @@ static void filemap_unaccount_folio(struct address_space *mapping, lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, -nr); } else if (folio_test_pmd_mappable(folio)) { lruvec_stat_mod_folio(folio, NR_FILE_THPS, -nr); - filemap_nr_thps_dec(mapping); } if (test_bit(AS_KERNEL_FILE, &folio->mapping->flags)) mod_node_page_state(folio_pgdat(folio), diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 009316de626df..fbbb0bab50de7 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3953,7 +3953,6 @@ static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int n } else { lruvec_stat_mod_folio(folio, NR_FILE_THPS, -nr); - filemap_nr_thps_dec(mapping); } } } diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 90332ac118d84..1e232022d2da9 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2489,21 +2489,6 @@ out_unlock: goto xa_unlocked; } - if (!is_shmem) { - filemap_nr_thps_inc(mapping); - /* - * Paired with the fence in do_dentry_open() -> get_write_access() - * to ensure i_writecount is up to date and the update to nr_thps - * is visible. Ensures the page cache will be truncated if the - * file is opened writable. - */ - smp_mb(); - if (inode_is_open_for_write(mapping->host)) { - result = SCAN_FAIL; - filemap_nr_thps_dec(mapping); - } - } - xa_locked: xas_unlock_irq(&xas); xa_unlocked: @@ -2681,19 +2666,6 @@ rollback: folio_putback_lru(folio); folio_put(folio); } - /* - * Undo the updates of filemap_nr_thps_inc for non-SHMEM - * file only. This undo is not needed unless failure is - * due to SCAN_COPY_MC. - */ - if (!is_shmem && result == SCAN_COPY_MC) { - filemap_nr_thps_dec(mapping); - /* - * Paired with the fence in do_dentry_open() -> get_write_access() - * to ensure the update to nr_thps is visible. - */ - smp_mb(); - } new_folio->mapping = NULL; |