| Message ID | 20250228174953.2222831-1-ziy@nvidia.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] mm/migrate: fix shmem xarray update during migration | expand |
On 2025/3/1 01:49, Zi Yan wrote: > Pagecache uses multi-index entries for large folio, so does shmem. Only > swap cache still stores multiple entries for a single large folio. > Commit fc346d0a70a1 ("mm: migrate high-order folios in swap cache correctly") > fixed swap cache but got shmem wrong by storing multiple entries for > a large shmem folio. Fix it by storing a single entry for a shmem > folio. > > Fixes: fc346d0a70a1 ("mm: migrate high-order folios in swap cache correctly") > Reported-by: Liu Shixin <liushixin2@huawei.com> > Closes: https://lore.kernel.org/all/28546fb4-5210-bf75-16d6-43e1f8646080@huawei.com/ > Signed-off-by: Zi Yan <ziy@nvidia.com> > Reviewed-by: Shivank Garg <shivankg@amd.com> LGTM. Thanks. Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> > --- > mm/migrate.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/mm/migrate.c b/mm/migrate.c > index 365c6daa8d1b..2c9669135a38 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -524,7 +524,11 @@ static int __folio_migrate_mapping(struct address_space *mapping, > folio_set_swapcache(newfolio); > newfolio->private = folio_get_private(folio); > } > - entries = nr; > + /* shmem uses high-order entry */ > + if (!folio_test_anon(folio)) > + entries = 1; > + else > + entries = nr; > } else { > VM_BUG_ON_FOLIO(folio_test_swapcache(folio), folio); > entries = 1;
diff --git a/mm/migrate.c b/mm/migrate.c index 365c6daa8d1b..2c9669135a38 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -524,7 +524,11 @@ static int __folio_migrate_mapping(struct address_space *mapping, folio_set_swapcache(newfolio); newfolio->private = folio_get_private(folio); } - entries = nr; + /* shmem uses high-order entry */ + if (!folio_test_anon(folio)) + entries = 1; + else + entries = nr; } else { VM_BUG_ON_FOLIO(folio_test_swapcache(folio), folio); entries = 1;
Pagecache uses multi-index entries for large folio, so does shmem. Only swap cache still stores multiple entries for a single large folio. Commit fc346d0a70a1 ("mm: migrate high-order folios in swap cache correctly") fixed swap cache but got shmem wrong by storing multiple entries for a large shmem folio. Fix it by storing a single entry for a shmem folio. Fixes: fc346d0a70a1 ("mm: migrate high-order folios in swap cache correctly") Reported-by: Liu Shixin <liushixin2@huawei.com> Closes: https://lore.kernel.org/all/28546fb4-5210-bf75-16d6-43e1f8646080@huawei.com/ Signed-off-by: Zi Yan <ziy@nvidia.com> Reviewed-by: Shivank Garg <shivankg@amd.com> --- mm/migrate.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)