Since the migratetype hygiene patches [0], the locking here is a bit more formalised. For other stuff, it's pretty obvious that it would be protected by the zone lock. But it didn't seem totally self-evident that it should protect the pageblock type. So it seems particularly helpful to have it written in the code. [0] https://lore.kernel.org/lkml/20240320180429.678181-3-hannes@xxxxxxxxxxx/T/ Signed-off-by: Brendan Jackman <jackmanb@xxxxxxxxxx> --- Note Vlastimil Acked the first version, I did not carry his ack since I've changed the diff. Not sure if I'm being overly pedantic there? Changes in v2: - Fixed missing in_mem_hotplug() setup for !CONFIG_MEMORY_HOTPLUG - Expanded commit message to include a bit more rationale - Link to v1: https://lore.kernel.org/r/20250227-pageblock-lockdep-v1-1-3701efb331bb@xxxxxxxxxx --- include/linux/memory_hotplug.h | 5 +++++ mm/memory_hotplug.c | 5 +++++ mm/page_alloc.c | 4 ++++ 3 files changed, 14 insertions(+) diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index eaac5ae8c05c8ee2f2868d5bc1b04d1f68235b3f..508a1d074527a3349c1c9789ecf35d5ab08a5ba6 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -175,6 +175,7 @@ void put_online_mems(void); void mem_hotplug_begin(void); void mem_hotplug_done(void); +bool in_mem_hotplug(void); /* See kswapd_is_running() */ static inline void pgdat_kswapd_lock(pg_data_t *pgdat) @@ -223,6 +224,10 @@ static inline void put_online_mems(void) {} static inline void mem_hotplug_begin(void) {} static inline void mem_hotplug_done(void) {} +static inline bool in_mem_hotplug(void) +{ + return false; +} static inline bool movable_node_is_enabled(void) { diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index e3655f07dd6e33efb3e811cab07f240649487441..c44c2765b21f1e9e4b2d68abda9ac161fb2869ec 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -267,6 +267,11 @@ void mem_hotplug_done(void) cpus_read_unlock(); } +bool in_mem_hotplug(void) +{ + return percpu_is_write_locked(&mem_hotplug_lock); +} + u64 max_mem_size = U64_MAX; /* add this memory to iomem resource */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 579789600a3c7bfb7b0d847d51af702a9d4b139a..1ed21179676d05c66f77f9dbebf88e36bbe402e9 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -417,6 +417,10 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags, void set_pageblock_migratetype(struct page *page, int migratetype) { + lockdep_assert_once(system_state == SYSTEM_BOOTING || + in_mem_hotplug() || + lockdep_is_held(&page_zone(page)->lock)); + if (unlikely(page_group_by_mobility_disabled && migratetype < MIGRATE_PCPTYPES)) migratetype = MIGRATE_UNMOVABLE; --- base-commit: 83c34e70d8dd67525c2547e8c5ee1a4bf37ac06b change-id: 20250227-pageblock-lockdep-9628c48d7e08 Best regards, -- Brendan Jackman <jackmanb@xxxxxxxxxx>
