* [merged] mm-page_alloc-explicitly-acquire-the-zone-lock-in-__free_pages_ok.patch removed from -mm tree
@ 2021-07-06 19:14 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2021-07-06 19:14 UTC (permalink / raw)
To: bigeasy, brouer, chuck.lever, mgorman, mhocko, mingo, mm-commits,
peterz, tglx, vbabka
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@techsingularity.net>
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@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
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@techsingularity.net are
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2021-07-06 19:14 [merged] mm-page_alloc-explicitly-acquire-the-zone-lock-in-__free_pages_ok.patch removed from -mm tree akpm
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