The patch titled
Subject: mm/page_alloc: explicitly acquire the zone lock in __free_pages_ok
has been removed from the -mm tree. Its filename was
mm-page_alloc-explicitly-acquire-the-zone-lock-in-__free_pages_ok.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Subject: mm/page_alloc: explicitly acquire the zone lock in __free_pages_ok
__free_pages_ok() disables IRQs before calling a common helper
free_one_page() that acquires the zone lock. This is not safe according
to Documentation/locking/locktypes.rst and in this context, IRQ disabling
is not protecting a per_cpu_pages structure either or a local_lock would
be used.
This patch explicitly acquires the lock with spin_lock_irqsave instead of
relying on a helper. This removes the last instance of local_irq_save()
in page_alloc.c.
Link: https://lkml.kernel.org/r/20210512095458.30632-8-mgorman@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Chuck Lever <chuck.lever@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
--- a/mm/page_alloc.c~mm-page_alloc-explicitly-acquire-the-zone-lock-in-__free_pages_ok
+++ a/mm/page_alloc.c
@@ -1590,21 +1590,21 @@ static void __free_pages_ok(struct page
unsigned long flags;
int migratetype;
unsigned long pfn = page_to_pfn(page);
+ struct zone *zone = page_zone(page);
if (!free_pages_prepare(page, order, true, fpi_flags))
return;
migratetype = get_pfnblock_migratetype(page, pfn);
- /*
- * TODO FIX: Disable IRQs before acquiring IRQ-safe zone->lock
- * and protect vmstat updates.
- */
- local_irq_save(flags);
+ spin_lock_irqsave(&zone->lock, flags);
__count_vm_events(PGFREE, 1 << order);
- free_one_page(page_zone(page), page, pfn, order, migratetype,
- fpi_flags);
- local_irq_restore(flags);
+ if (unlikely(has_isolate_pageblock(zone) ||
+ is_migrate_isolate(migratetype))) {
+ migratetype = get_pfnblock_migratetype(page, pfn);
+ }
+ __free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
+ spin_unlock_irqrestore(&zone->lock, flags);
}
void __free_pages_core(struct page *page, unsigned int order)
_
Patches currently in -mm which might be from mgorman@xxxxxxxxxxxxxxxxxxx are
