On Tue, Mar 19, 2024 at 05:27:30PM +0800, Kairui Song wrote:
> From: Kairui Song <kasong@xxxxxxxxxxx>
>
> xas_split_alloc could fail with NOMEM, and in such case, it should abort
> early instead of keep going and fail the xas_split below.
>
> Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx>
The usual way of programming with an xa_state is to not do any error
handling; the xas_ functions check for error and become no-ops, so we
only have to check at the end.
I think this case is worth making an exception for because we avoid
acquiring/releasing the lock. Not that we should be getting ENOMEM
very often; we only allocate about 8 nodes usually and we get 7
nodes/page.
Acked-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> mm/filemap.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 7437b2bd75c1..f07ea0b97698 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -880,9 +880,12 @@ noinline int __filemap_add_folio(struct address_space *mapping,
> unsigned int order = xa_get_order(xas.xa, xas.xa_index);
> void *entry, *old = NULL;
>
> - if (order > folio_order(folio))
> + if (order > folio_order(folio)) {
> xas_split_alloc(&xas, xa_load(xas.xa, xas.xa_index),
> order, gfp);
> + if (xas_error(&xas))
> + goto error;
> + }
> xas_lock_irq(&xas);
> xas_for_each_conflict(&xas, entry) {
> old = entry;
> --
> 2.43.0
>
