From: Mel Gorman <mgorman@techsingularity.net>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Chuck Lever <chuck.lever@oracle.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>, Michal Hocko <mhocko@kernel.org>,
Vlastimil Babka <vbabka@suse.cz>, Linux-MM <linux-mm@kvack.org>,
Linux-RT-Users <linux-rt-users@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Mel Gorman <mgorman@techsingularity.net>
Subject: [PATCH 7/9] mm/page_alloc: Explicitly acquire the zone lock in __free_pages_ok
Date: Wed, 12 May 2021 10:54:56 +0100 [thread overview]
Message-ID: <20210512095458.30632-8-mgorman@techsingularity.net> (raw)
In-Reply-To: <20210512095458.30632-1-mgorman@techsingularity.net>
__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.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
---
mm/page_alloc.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5879b595b74b..7da70b404f4e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1579,21 +1579,21 @@ static void __free_pages_ok(struct page *page, unsigned int order,
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)
--
2.26.2
next prev parent reply other threads:[~2021-05-12 9:56 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-12 9:54 [PATCH 0/9 v6] Use local_lock for pcp protection and reduce stat overhead Mel Gorman
2021-05-12 9:54 ` [PATCH 1/9] mm/page_alloc: Split per cpu page lists and zone stats Mel Gorman
2021-05-12 9:54 ` [PATCH 2/9] mm/page_alloc: Convert per-cpu list protection to local_lock Mel Gorman
2021-05-12 9:54 ` [PATCH 3/9] mm/vmstat: Convert NUMA statistics to basic NUMA counters Mel Gorman
2021-05-12 10:11 ` Vlastimil Babka
2021-05-12 9:54 ` [PATCH 4/9] mm/vmstat: Inline NUMA event counter updates Mel Gorman
2021-05-12 9:54 ` [PATCH 5/9] mm/page_alloc: Batch the accounting updates in the bulk allocator Mel Gorman
2021-05-12 9:54 ` [PATCH 6/9] mm/page_alloc: Reduce duration that IRQs are disabled for VM counters Mel Gorman
2021-05-12 9:54 ` Mel Gorman [this message]
2021-05-12 9:54 ` [PATCH 8/9] mm/page_alloc: Avoid conflating IRQs disabled with zone->lock Mel Gorman
2021-05-12 9:54 ` [PATCH 9/9] mm/page_alloc: Update PGFREE outside the zone lock in __free_pages_ok Mel Gorman
2021-05-12 13:06 ` [PATCH 0/9 v6] Use local_lock for pcp protection and reduce stat overhead Peter Zijlstra
-- strict thread matches above, loose matches on Subject: below --
2021-04-22 11:14 [PATCH 0/9 v5] " Mel Gorman
2021-04-22 11:14 ` [PATCH 7/9] mm/page_alloc: Explicitly acquire the zone lock in __free_pages_ok Mel Gorman
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