Re: [PATCH v4 06/11] mm/migrate: make a standard migration target allocation function

From: Michal Hocko
Date: Tue Jul 07 2020 - 07:43:38 EST


On Tue 07-07-20 16:44:44, Joonsoo Kim wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
>
> There are some similar functions for migration target allocation. Since
> there is no fundamental difference, it's better to keep just one rather
> than keeping all variants. This patch implements base migration target
> allocation function. In the following patches, variants will be converted
> to use this function.
>
> Changes should be mechanical but there are some differences. First, Some
> callers' nodemask is assgined to NULL since NULL nodemask will be
> considered as all available nodes, that is, &node_states[N_MEMORY].
> Second, for hugetlb page allocation, gfp_mask is ORed since a user could
> provide a gfp_mask from now on. Third, if provided node id is NUMA_NO_NODE,
> node id is set up to the node where migration source lives.
>
> Note that PageHighmem() call in previous function is changed to open-code
> "is_highmem_idx()" since it provides more readability.
>
> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>

Acked-by: Michal Hocko <mhocko@xxxxxxxx>

Thanks!

> ---
> include/linux/migrate.h | 9 +++++----
> mm/internal.h | 7 +++++++
> mm/memory-failure.c | 7 +++++--
> mm/memory_hotplug.c | 14 +++++++++-----
> mm/migrate.c | 27 +++++++++++++++++----------
> mm/page_isolation.c | 7 +++++--
> 6 files changed, 48 insertions(+), 23 deletions(-)
>
> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
> index 1d70b4a..cc56f0d 100644
> --- a/include/linux/migrate.h
> +++ b/include/linux/migrate.h
> @@ -10,6 +10,8 @@
> typedef struct page *new_page_t(struct page *page, unsigned long private);
> typedef void free_page_t(struct page *page, unsigned long private);
>
> +struct migration_target_control;
> +
> /*
> * Return values from addresss_space_operations.migratepage():
> * - negative errno on page migration failure;
> @@ -39,8 +41,7 @@ extern int migrate_page(struct address_space *mapping,
> enum migrate_mode mode);
> extern int migrate_pages(struct list_head *l, new_page_t new, free_page_t free,
> unsigned long private, enum migrate_mode mode, int reason);
> -extern struct page *new_page_nodemask(struct page *page,
> - int preferred_nid, nodemask_t *nodemask);
> +extern struct page *alloc_migration_target(struct page *page, unsigned long private);
> extern int isolate_movable_page(struct page *page, isolate_mode_t mode);
> extern void putback_movable_page(struct page *page);
>
> @@ -59,8 +60,8 @@ static inline int migrate_pages(struct list_head *l, new_page_t new,
> free_page_t free, unsigned long private, enum migrate_mode mode,
> int reason)
> { return -ENOSYS; }
> -static inline struct page *new_page_nodemask(struct page *page,
> - int preferred_nid, nodemask_t *nodemask)
> +static inline struct page *alloc_migration_target(struct page *page,
> + unsigned long private)
> { return NULL; }
> static inline int isolate_movable_page(struct page *page, isolate_mode_t mode)
> { return -EBUSY; }
> diff --git a/mm/internal.h b/mm/internal.h
> index dd14c53..0beacf3 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -614,4 +614,11 @@ static inline bool is_migrate_highatomic_page(struct page *page)
>
> void setup_zone_pageset(struct zone *zone);
> extern struct page *alloc_new_node_page(struct page *page, unsigned long node);
> +
> +struct migration_target_control {
> + int nid; /* preferred node id */
> + nodemask_t *nmask;
> + gfp_t gfp_mask;
> +};
> +
> #endif /* __MM_INTERNAL_H */
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index c5e4cee..609d42b6 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1679,9 +1679,12 @@ EXPORT_SYMBOL(unpoison_memory);
>
> static struct page *new_page(struct page *p, unsigned long private)
> {
> - int nid = page_to_nid(p);
> + struct migration_target_control mtc = {
> + .nid = page_to_nid(p),
> + .gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
> + };
>
> - return new_page_nodemask(p, nid, &node_states[N_MEMORY]);
> + return alloc_migration_target(p, (unsigned long)&mtc);
> }
>
> /*
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index cafe65eb..86bc2ad 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1267,19 +1267,23 @@ static int scan_movable_pages(unsigned long start, unsigned long end,
>
> static struct page *new_node_page(struct page *page, unsigned long private)
> {
> - int nid = page_to_nid(page);
> nodemask_t nmask = node_states[N_MEMORY];
> + struct migration_target_control mtc = {
> + .nid = page_to_nid(page),
> + .nmask = &nmask,
> + .gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
> + };
>
> /*
> * try to allocate from a different node but reuse this node if there
> * are no other online nodes to be used (e.g. we are offlining a part
> * of the only existing node)
> */
> - node_clear(nid, nmask);
> - if (nodes_empty(nmask))
> - node_set(nid, nmask);
> + node_clear(mtc.nid, *mtc.nmask);
> + if (nodes_empty(*mtc.nmask))
> + node_set(mtc.nid, *mtc.nmask);
>
> - return new_page_nodemask(page, nid, &nmask);
> + return alloc_migration_target(page, (unsigned long)&mtc);
> }
>
> static int
> diff --git a/mm/migrate.c b/mm/migrate.c
> index ecd7615..00cd81c 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1531,19 +1531,27 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
> return rc;
> }
>
> -struct page *new_page_nodemask(struct page *page,
> - int preferred_nid, nodemask_t *nodemask)
> +struct page *alloc_migration_target(struct page *page, unsigned long private)
> {
> - gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL;
> + struct migration_target_control *mtc;
> + gfp_t gfp_mask;
> unsigned int order = 0;
> struct page *new_page = NULL;
> + int nid;
> + int zidx;
> +
> + mtc = (struct migration_target_control *)private;
> + gfp_mask = mtc->gfp_mask;
> + nid = mtc->nid;
> + if (nid == NUMA_NO_NODE)
> + nid = page_to_nid(page);
>
> if (PageHuge(page)) {
> struct hstate *h = page_hstate(compound_head(page));
>
> - gfp_mask = htlb_alloc_mask(h);
> - return alloc_huge_page_nodemask(h, preferred_nid,
> - nodemask, gfp_mask, false);
> + gfp_mask |= htlb_alloc_mask(h);
> + return alloc_huge_page_nodemask(h, nid, mtc->nmask,
> + gfp_mask, false);
> }
>
> if (PageTransHuge(page)) {
> @@ -1555,12 +1563,11 @@ struct page *new_page_nodemask(struct page *page,
> gfp_mask |= GFP_TRANSHUGE;
> order = HPAGE_PMD_ORDER;
> }
> -
> - if (PageHighMem(page) || (zone_idx(page_zone(page)) == ZONE_MOVABLE))
> + zidx = zone_idx(page_zone(page));
> + if (is_highmem_idx(zidx) || zidx == ZONE_MOVABLE)
> gfp_mask |= __GFP_HIGHMEM;
>
> - new_page = __alloc_pages_nodemask(gfp_mask, order,
> - preferred_nid, nodemask);
> + new_page = __alloc_pages_nodemask(gfp_mask, order, nid, mtc->nmask);
>
> if (new_page && PageTransHuge(new_page))
> prep_transhuge_page(new_page);
> diff --git a/mm/page_isolation.c b/mm/page_isolation.c
> index aec26d9..f25c66e 100644
> --- a/mm/page_isolation.c
> +++ b/mm/page_isolation.c
> @@ -309,7 +309,10 @@ int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
>
> struct page *alloc_migrate_target(struct page *page, unsigned long private)
> {
> - int nid = page_to_nid(page);
> + struct migration_target_control mtc = {
> + .nid = page_to_nid(page),
> + .gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
> + };
>
> - return new_page_nodemask(page, nid, &node_states[N_MEMORY]);
> + return alloc_migration_target(page, (unsigned long)&mtc);
> }
> --
> 2.7.4

--
Michal Hocko
SUSE Labs