From: john.hubbard@gmail.com
To: linux-mm@kvack.org
Cc: 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>,
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>
Subject: [PATCH v2 5/6] mm: introduce zone_gup_lock, for dma-pinned pages
Date: Sat, 10 Nov 2018 00:50:40 -0800 [thread overview]
Message-ID: <20181110085041.10071-6-jhubbard@nvidia.com> (raw)
In-Reply-To: <20181110085041.10071-1-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.
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Christopher Lameter <cl@linux.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jan Kara <jack@suse.cz>
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 847705a6d0ec..125a6f34f6ba 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -660,6 +660,7 @@ 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;
@@ -729,6 +730,11 @@ 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 a919ba5cb3c8..7cc0d9bdba17 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6305,6 +6305,7 @@ 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:[~2018-11-10 8:50 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-10 8:50 [PATCH v2 0/6] RFC: gup+dma: tracking dma-pinned pages john.hubbard
2018-11-10 8:50 ` [PATCH v2 1/6] mm/gup: finish consolidating error handling john.hubbard
2018-11-12 15:41 ` Keith Busch
2018-11-12 16:14 ` Dan Williams
2018-11-15 0:45 ` John Hubbard
2018-11-10 8:50 ` [PATCH v2 2/6] mm: introduce put_user_page*(), placeholder versions john.hubbard
2018-11-11 14:10 ` Mike Rapoport
2018-11-10 8:50 ` [PATCH v2 3/6] infiniband/mm: convert put_page() to put_user_page*() john.hubbard
2018-11-10 8:50 ` [PATCH v2 4/6] mm: introduce page->dma_pinned_flags, _count john.hubbard
2018-11-10 8:50 ` john.hubbard [this message]
2018-11-10 8:50 ` [PATCH v2 6/6] mm: track gup pages with page->dma_pinned_* fields john.hubbard
2018-11-12 13:58 ` Jan Kara
2018-11-15 6:28 ` [LKP] [mm] 0e9755bfa2: kernel_BUG_at_include/linux/mm.h kernel test robot
2018-11-19 18:57 ` [PATCH v2 0/6] RFC: gup+dma: tracking dma-pinned pages Tom Talpey
2018-11-21 6:09 ` John Hubbard
2018-11-21 16:49 ` Tom Talpey
2018-11-21 22:06 ` John Hubbard
2018-11-28 1:21 ` Tom Talpey
2018-11-28 2:52 ` John Hubbard
2018-11-28 13:59 ` Tom Talpey
2018-11-30 1:39 ` John Hubbard
2018-11-30 2:18 ` Tom Talpey
2018-11-30 2:21 ` John Hubbard
2018-11-30 2:30 ` Tom Talpey
2018-11-30 3:00 ` John Hubbard
2018-11-30 3:14 ` Tom Talpey
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