On 22-Aug-23 6:23 AM, Baolin Wang wrote:
> Move the numamigrate_isolate_page() into do_numa_page() to simplify the
> migrate_misplaced_page(), which now only focuses on page migration, and
> it also serves as a preparation for supporting batch migration for
> migrate_misplaced_page().
>
> While we are at it, change the numamigrate_isolate_page() to boolean
> type to make the return value more clear.
>
> Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> ---
> include/linux/migrate.h | 6 ++++++
> mm/huge_memory.c | 7 +++++++
> mm/memory.c | 7 +++++++
> mm/migrate.c | 22 +++++++---------------
> 4 files changed, 27 insertions(+), 15 deletions(-)
>
> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
> index 711dd9412561..ddcd62ec2c12 100644
> --- a/include/linux/migrate.h
> +++ b/include/linux/migrate.h
> @@ -144,12 +144,18 @@ const struct movable_operations *page_movable_ops(struct page *page)
> #ifdef CONFIG_NUMA_BALANCING
> int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
> int node);
> +bool numamigrate_isolate_page(pg_data_t *pgdat, struct page *page);
> #else
> static inline int migrate_misplaced_page(struct page *page,
> struct vm_area_struct *vma, int node)
> {
> return -EAGAIN; /* can't migrate now */
> }
> +
> +static inline bool numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
> +{
> + return false;
> +}
> #endif /* CONFIG_NUMA_BALANCING */
>
> #ifdef CONFIG_MIGRATION
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 4a9b34a89854..07149ead11e4 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1496,6 +1496,7 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
> int target_nid, last_cpupid = (-1 & LAST_CPUPID_MASK);
> bool migrated = false, writable = false;
> int flags = 0;
> + pg_data_t *pgdat;
>
> vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
> if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
> @@ -1545,6 +1546,12 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
> goto migrate_fail;
> }
>
> + pgdat = NODE_DATA(target_nid);
> + if (!numamigrate_isolate_page(pgdat, page)) {
> + put_page(page);
> + goto migrate_fail;
> + }
> +
> migrated = migrate_misplaced_page(page, vma, target_nid);
> if (migrated) {
> flags |= TNF_MIGRATED;
> diff --git a/mm/memory.c b/mm/memory.c
> index fc6f6b7a70e1..4e451b041488 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4769,6 +4769,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
> int target_nid;
> pte_t pte, old_pte;
> int flags = 0;
> + pg_data_t *pgdat;
>
> /*
> * The "pte" at this point cannot be used safely without
> @@ -4844,6 +4845,12 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
> goto migrate_fail;
> }
>
> + pgdat = NODE_DATA(target_nid);
> + if (!numamigrate_isolate_page(pgdat, page)) {
> + put_page(page);
> + goto migrate_fail;
> + }
> +
> /* Migrate to the requested node */
> if (migrate_misplaced_page(page, vma, target_nid)) {
> page_nid = target_nid;
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 9cc98fb1d6ec..0b2b69a2a7ab 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -2478,7 +2478,7 @@ static struct folio *alloc_misplaced_dst_folio(struct folio *src,
> return __folio_alloc_node(gfp, order, nid);
> }
>
> -static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
> +bool numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
> {
> int nr_pages = thp_nr_pages(page);
> int order = compound_order(page);
> @@ -2496,11 +2496,11 @@ static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
> break;
> }
There is an other s/return 0/return false/ changed required here for this chunk:
if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING))
return 0;
> wakeup_kswapd(pgdat->node_zones + z, 0, order, ZONE_MOVABLE);
> - return 0;
> + return false;
> }
Looks like this whole section under "Avoiding migrating to a node that is nearly full"
check could be moved to numa_page_can_migrate() as that can be considered as one more
check (or action to) see if the page can be migrated or not. After that numamigrate_isolate_page()
will truly be about isolating the page.
Regards,
Bharata.
