From: john.hubbard@gmail.com
To: Matthew Wilcox <willy@infradead.org>,
Michal Hocko <mhocko@kernel.org>,
Christopher Lameter <cl@linux.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
Dan Williams <dan.j.williams@intel.com>, Jan Kara <jack@suse.cz>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-rdma <linux-rdma@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, John Hubbard <jhubbard@nvidia.com>
Subject: [PATCH 5/6] mm: introduce zone_gup_lock, for dma-pinned pages
Date: Thu, 11 Oct 2018 23:00:13 -0700 [thread overview]
Message-ID: <20181012060014.10242-6-jhubbard@nvidia.com> (raw)
In-Reply-To: <20181012060014.10242-1-jhubbard@nvidia.com>
From: John Hubbard <jhubbard@nvidia.com>
The page->dma_pinned_flags and _count fields require
lock protection. A lock at approximately the granularity
of the zone_lru_lock is called for, but adding to the
locking contention of zone_lru_lock is undesirable,
because that is a pre-existing hot spot. Fortunately,
these new dma_pinned_* fields can use an independent
lock, so this patch creates an entirely new lock, right
next to the zone_lru_lock.
Why "zone_gup_lock"?
Most of the naming refers to "DMA-pinned pages", but
"zone DMA lock" has other meanings already, so this is
called zone_gup_lock instead. The "dma pinning" is a result
of get_user_pages (gup) being called, so the name still
helps explain its use.
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
include/linux/mmzone.h | 6 ++++++
mm/page_alloc.c | 1 +
2 files changed, 7 insertions(+)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index d4b0c79d2924..971a63f84ad5 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -661,6 +661,7 @@ typedef struct pglist_data {
enum zone_type kswapd_classzone_idx;
int kswapd_failures; /* Number of 'reclaimed == 0' runs */
+ spinlock_t pinned_dma_lock;
#ifdef CONFIG_COMPACTION
int kcompactd_max_order;
@@ -730,6 +731,11 @@ static inline spinlock_t *zone_lru_lock(struct zone *zone)
return &zone->zone_pgdat->lru_lock;
}
+static inline spinlock_t *zone_gup_lock(struct zone *zone)
+{
+ return &zone->zone_pgdat->pinned_dma_lock;
+}
+
static inline struct lruvec *node_lruvec(struct pglist_data *pgdat)
{
return &pgdat->lruvec;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e2ef1c17942f..850f90223cc7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6225,6 +6225,7 @@ static void __meminit pgdat_init_internals(struct pglist_data *pgdat)
pgdat_page_ext_init(pgdat);
spin_lock_init(&pgdat->lru_lock);
+ spin_lock_init(&pgdat->pinned_dma_lock);
lruvec_init(node_lruvec(pgdat));
}
--
2.19.1
next prev parent reply other threads:[~2018-10-12 6:00 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-12 6:00 [PATCH 0/6] RFC: gup+dma: tracking dma-pinned pages john.hubbard
2018-10-12 6:00 ` [PATCH 1/6] mm: get_user_pages: consolidate error handling john.hubbard
2018-10-12 6:30 ` Balbir Singh
2018-10-12 22:45 ` John Hubbard
2018-10-12 6:00 ` [PATCH 2/6] mm: introduce put_user_page*(), placeholder versions john.hubbard
2018-10-12 7:35 ` Balbir Singh
2018-10-12 22:31 ` John Hubbard
2018-10-12 6:00 ` [PATCH 3/6] infiniband/mm: convert put_page() to put_user_page*() john.hubbard
2018-10-12 6:00 ` [PATCH 4/6] mm: introduce page->dma_pinned_flags, _count john.hubbard
2018-10-12 10:56 ` Balbir Singh
2018-10-13 0:15 ` John Hubbard
2018-10-24 11:00 ` Balbir Singh
2018-11-02 23:27 ` John Hubbard
2018-10-13 3:55 ` Dave Chinner
2018-10-13 7:34 ` John Hubbard
2018-10-13 16:47 ` Christoph Hellwig
2018-10-13 21:19 ` John Hubbard
2018-11-05 7:10 ` John Hubbard
2018-11-05 9:54 ` Jan Kara
2018-11-06 0:26 ` John Hubbard
2018-11-06 2:47 ` Dave Chinner
2018-11-06 11:00 ` Jan Kara
2018-11-06 20:41 ` Dave Chinner
2018-11-07 6:36 ` John Hubbard
2018-10-13 23:01 ` Dave Chinner
2018-10-16 8:51 ` Jan Kara
2018-10-17 1:48 ` John Hubbard
2018-10-17 11:09 ` Michal Hocko
2018-10-18 0:03 ` John Hubbard
2018-10-19 8:11 ` Michal Hocko
2018-10-12 6:00 ` john.hubbard [this message]
2018-10-12 6:00 ` [PATCH 6/6] mm: track gup pages with page->dma_pinned_* fields john.hubbard
2018-10-12 11:07 ` Balbir Singh
2018-10-13 0:33 ` John Hubbard
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