David Hildenbrand <david@xxxxxxxxxx> writes:
> Let's just return 0 on success, which is less confusing.
>
> ... especially because we got it wrong in the migrate.h stub where we
> have "return -EAGAIN; /* can't migrate now */" instead of "return 0;".
> Likely this wrong return value doesn't currently matter, but it
> certainly adds confusion.
>
> We'll add migrate_misplaced_folio_prepare() next, where we want to use
> the same "return 0 on success" approach, so let's just clean this up.
>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
> ---
> mm/huge_memory.c | 5 ++---
> mm/memory.c | 2 +-
> mm/migrate.c | 4 ++--
> 3 files changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 0fffaa58a47a..fc27dabcd8e3 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1652,7 +1652,7 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
> unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
> int nid = NUMA_NO_NODE;
> int target_nid, last_cpupid = (-1 & LAST_CPUPID_MASK);
> - bool migrated = false, writable = false;
> + bool writable = false;
> int flags = 0;
>
> vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
> @@ -1696,8 +1696,7 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
> spin_unlock(vmf->ptl);
> writable = false;
>
> - migrated = migrate_misplaced_folio(folio, vma, target_nid);
> - if (migrated) {
> + if (!migrate_misplaced_folio(folio, vma, target_nid)) {
> flags |= TNF_MIGRATED;
> nid = target_nid;
> } else {
> diff --git a/mm/memory.c b/mm/memory.c
> index 00728ea95583..118660de5bcc 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -5354,7 +5354,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
> ignore_writable = true;
>
> /* Migrate to the requested node */
> - if (migrate_misplaced_folio(folio, vma, target_nid)) {
> + if (!migrate_misplaced_folio(folio, vma, target_nid)) {
> nid = target_nid;
> flags |= TNF_MIGRATED;
> } else {
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 781979567f64..0307b54879a0 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -2629,11 +2629,11 @@ int migrate_misplaced_folio(struct folio *folio, struct vm_area_struct *vma,
> nr_succeeded);
> }
> BUG_ON(!list_empty(&migratepages));
> - return isolated;
> + return isolated ? 0 : -EAGAIN;
Is it good to use -EAGAIN as error code always? At least if
nr_remaining < 0, we can use that?
Otherwise, this LGTM. Thanks!
>
> out:
> folio_put(folio);
> - return 0;
> + return -EAGAIN;
> }
> #endif /* CONFIG_NUMA_BALANCING */
> #endif /* CONFIG_NUMA */
--
Best Regards,
Huang, Ying
