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Message-ID: <63ba9fe3-e384-4396-bd86-fe62150ed1ab@redhat.com>
Date: Mon, 19 May 2025 10:21:41 +0200
From: David Hildenbrand <david@...hat.com>
To: Zi Yan <ziy@...dia.com>, Oscar Salvador <osalvador@...e.de>,
Johannes Weiner <hannes@...xchg.org>, linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Vlastimil Babka <vbabka@...e.cz>, Baolin Wang
<baolin.wang@...ux.alibaba.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Mel Gorman <mgorman@...hsingularity.net>,
Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
Brendan Jackman <jackmanb@...gle.com>, Richard Chang
<richardycc@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/4] mm/page_isolation: remove migratetype from
move_freepages_block_isolate()
On 09.05.25 22:01, Zi Yan wrote:
> Since migratetype is no longer overwritten during pageblock isolation,
> moving pageblocks to and from MIGRATE_ISOLATE no longer needs migratetype.
>
> Add MIGRATETYPE_NO_ISO_MASK to allow read before-isolation migratetype
> when a pageblock is isolated. It is used by move_freepages_block_isolate().
>
> Add pageblock_isolate_and_move_free_pages() and
> pageblock_unisolate_and_move_free_pages() to be explicit about the page
> isolation operations. Both share the common code in
> __move_freepages_block_isolate(), which is renamed from
> move_freepages_block_isolate().
>
> Make set_pageblock_migratetype() only accept non MIGRATE_ISOLATE types,
> so that one should use set_pageblock_isolate() to isolate pageblocks.
>
> Two consequential changes:
> 1. move pageblock migratetype code out of __move_freepages_block().
> 2. in online_pages() from mm/memory_hotplug.c, move_pfn_range_to_zone() is
> called with MIGRATE_MOVABLE instead of MIGRATE_ISOLATE and all affected
> pageblocks are isolated afterwards. Otherwise, all online pageblocks
> will have non-determined migratetype.
>
> Signed-off-by: Zi Yan <ziy@...dia.com>
> ---
> include/linux/mmzone.h | 4 +-
> include/linux/page-isolation.h | 5 ++-
> mm/memory_hotplug.c | 7 +++-
> mm/page_alloc.c | 73 +++++++++++++++++++++++++---------
> mm/page_isolation.c | 27 ++++++++-----
> 5 files changed, 82 insertions(+), 34 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 7ef01fe148ce..f66895456974 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -107,8 +107,10 @@ static inline bool migratetype_is_mergeable(int mt)
> extern int page_group_by_mobility_disabled;
>
> #ifdef CONFIG_MEMORY_ISOLATION
> -#define MIGRATETYPE_MASK ((BIT(PB_migratetype_bits) - 1) | PB_migrate_isolate_bit)
> +#define MIGRATETYPE_NO_ISO_MASK (BIT(PB_migratetype_bits) - 1)
> +#define MIGRATETYPE_MASK (MIGRATETYPE_NO_ISO_MASK | PB_migrate_isolate_bit)
> #else
> +#define MIGRATETYPE_NO_ISO_MASK MIGRATETYPE_MASK
> #define MIGRATETYPE_MASK (BIT(PB_migratetype_bits) - 1)
> #endif
>
> diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
> index 898bb788243b..b0a2af0a5357 100644
> --- a/include/linux/page-isolation.h
> +++ b/include/linux/page-isolation.h
> @@ -26,9 +26,10 @@ static inline bool is_migrate_isolate(int migratetype)
> #define REPORT_FAILURE 0x2
>
> void set_pageblock_migratetype(struct page *page, int migratetype);
> +void set_pageblock_isolate(struct page *page);
>
> -bool move_freepages_block_isolate(struct zone *zone, struct page *page,
> - int migratetype);
> +bool pageblock_isolate_and_move_free_pages(struct zone *zone, struct page *page);
> +bool pageblock_unisolate_and_move_free_pages(struct zone *zone, struct page *page);
>
> int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
> int migratetype, int flags);
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index b1caedbade5b..c86c47bba019 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1178,6 +1178,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages,
> const int nid = zone_to_nid(zone);
> int ret;
> struct memory_notify arg;
> + unsigned long isol_pfn;
>
> /*
> * {on,off}lining is constrained to full memory sections (or more
> @@ -1192,7 +1193,11 @@ int online_pages(unsigned long pfn, unsigned long nr_pages,
>
>
> /* associate pfn range with the zone */
> - move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_ISOLATE);
> + move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_MOVABLE);
> + for (isol_pfn = pfn;
> + isol_pfn < pfn + nr_pages;
> + isol_pfn += pageblock_nr_pages)
> + set_pageblock_isolate(pfn_to_page(isol_pfn));
Can we move that all the way into memmap_init_range(), where we do the
set_pageblock_migratetype()?
The MIGRATE_UNMOVABLE in mhp_init_memmap_on_memory() is likely fine: all
pages in that pageblock will be used for the memmap. Everything is unmovable,
but no free pages so ... nobody cares? :)
diff --git a/mm/internal.h b/mm/internal.h
index 6b8ed20177432..bc102846fcf1f 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -821,7 +821,7 @@ extern void *memmap_alloc(phys_addr_t size, phys_addr_t align,
int nid, bool exact_nid);
void memmap_init_range(unsigned long, int, unsigned long, unsigned long,
- unsigned long, enum meminit_context, struct vmem_altmap *, int);
+ unsigned long, enum meminit_context, struct vmem_altmap *, bool);
#if defined CONFIG_COMPACTION || defined CONFIG_CMA
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index b1caedbade5b1..4b2cf20ad21fb 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -764,13 +764,13 @@ static inline void section_taint_zone_device(unsigned long pfn)
* and resizing the pgdat/zone data to span the added pages. After this
* call, all affected pages are PageOffline().
*
- * All aligned pageblocks are initialized to the specified migratetype
- * (usually MIGRATE_MOVABLE). Besides setting the migratetype, no related
- * zone stats (e.g., nr_isolate_pageblock) are touched.
+ * All aligned pageblocks are initialized to MIGRATE_MOVABLE, and are isolated
+ * if requested. Besides setting the migratetype, no related zone stats (e.g.,
+ * nr_isolate_pageblock) are touched.
*/
void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
unsigned long nr_pages,
- struct vmem_altmap *altmap, int migratetype)
+ struct vmem_altmap *altmap, bool isolate)
{
struct pglist_data *pgdat = zone->zone_pgdat;
int nid = pgdat->node_id;
@@ -802,7 +802,7 @@ void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
* are reserved so nobody should be touching them so we should be safe
*/
memmap_init_range(nr_pages, nid, zone_idx(zone), start_pfn, 0,
- MEMINIT_HOTPLUG, altmap, migratetype);
+ MEMINIT_HOTPLUG, altmap, isolate);
set_zone_contiguous(zone);
}
@@ -1127,7 +1127,7 @@ int mhp_init_memmap_on_memory(unsigned long pfn, unsigned long nr_pages,
if (mhp_off_inaccessible)
page_init_poison(pfn_to_page(pfn), sizeof(struct page) * nr_pages);
- move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_UNMOVABLE);
+ move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, false);
for (i = 0; i < nr_pages; i++) {
struct page *page = pfn_to_page(pfn + i);
@@ -1192,7 +1192,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages,
/* associate pfn range with the zone */
- move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_ISOLATE);
+ move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, true);
arg.start_pfn = pfn;
arg.nr_pages = nr_pages;
diff --git a/mm/memremap.c b/mm/memremap.c
index c417c843e9b1f..e47f6809f254b 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -254,7 +254,7 @@ static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params,
zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE];
move_pfn_range_to_zone(zone, PHYS_PFN(range->start),
PHYS_PFN(range_len(range)), params->altmap,
- MIGRATE_MOVABLE);
+ false);
}
mem_hotplug_done();
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 1c5444e188f82..041106fc524be 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -867,14 +867,14 @@ static void __init init_unavailable_range(unsigned long spfn,
* up by memblock_free_all() once the early boot process is
* done. Non-atomic initialization, single-pass.
*
- * All aligned pageblocks are initialized to the specified migratetype
- * (usually MIGRATE_MOVABLE). Besides setting the migratetype, no related
- * zone stats (e.g., nr_isolate_pageblock) are touched.
+ * All aligned pageblocks are initialized to MIGRATE_MOVABLE, and are isolated
+ * if requested. Besides setting the migratetype, no related zone stats (e.g.,
+ * nr_isolate_pageblock) are touched.
*/
void __meminit memmap_init_range(unsigned long size, int nid, unsigned long zone,
unsigned long start_pfn, unsigned long zone_end_pfn,
enum meminit_context context,
- struct vmem_altmap *altmap, int migratetype)
+ struct vmem_altmap *altmap, bool isolate)
{
unsigned long pfn, end_pfn = start_pfn + size;
struct page *page;
@@ -931,7 +931,9 @@ void __meminit memmap_init_range(unsigned long size, int nid, unsigned long zone
* over the place during system boot.
*/
if (pageblock_aligned(pfn)) {
- set_pageblock_migratetype(page, migratetype);
+ set_pageblock_migratetype(page, MIGRATE_MOVABLE);
+ if (isolate)
+ set_pageblock_isolate(page, isolate)
cond_resched();
}
pfn++;
@@ -954,7 +956,7 @@ static void __init memmap_init_zone_range(struct zone *zone,
return;
memmap_init_range(end_pfn - start_pfn, nid, zone_id, start_pfn,
- zone_end_pfn, MEMINIT_EARLY, NULL, MIGRATE_MOVABLE);
+ zone_end_pfn, MEMINIT_EARLY, NULL, false);
if (*hole_pfn < start_pfn)
init_unavailable_range(*hole_pfn, start_pfn, zone_id, nid);
--
2.49.0
As an alterantive, a second "isolate" parameter and make sure that migratetype is
never MIGRATE_ISOLATE.
[...]
> --- a/mm/page_isolation.c
> +++ b/mm/page_isolation.c
> @@ -25,6 +25,12 @@ static inline void clear_pageblock_isolate(struct page *page)
> set_pfnblock_flags_mask(page, 0, page_to_pfn(page),
> PB_migrate_isolate_bit);
> }
> +void set_pageblock_isolate(struct page *page)
> +{
> + set_pfnblock_flags_mask(page, PB_migrate_isolate_bit,
> + page_to_pfn(page),
> + PB_migrate_isolate_bit);
> +}
Probably better placed in the previous patch, and in the header (see comment to #1).
--
Cheers,
David / dhildenb
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