From: Ralph Campbell <rcampbell@nvidia.com>
To: <linux-mm@kvack.org>
Cc: linux-kernel@vger.kernel.org,
"Ralph Campbell" <rcampbell@nvidia.com>,
"John Hubbard" <jhubbard@nvidia.com>,
"Matthew Wilcox" <willy@infradead.org>,
"Vlastimil Babka" <vbabka@suse.cz>,
"Christoph Lameter" <cl@linux.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
"Lai Jiangshan" <jiangshanlai@gmail.com>,
"Martin Schwidefsky" <schwidefsky@de.ibm.com>,
"Pekka Enberg" <penberg@kernel.org>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Andrey Ryabinin" <aryabinin@virtuozzo.com>,
"Christoph Hellwig" <hch@lst.de>,
"Jason Gunthorpe" <jgg@mellanox.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Linus Torvalds" <torvalds@linux-foundation.org>
Subject: [PATCH v2 1/3] mm: document zone device struct page field usage
Date: Fri, 19 Jul 2019 12:29:53 -0700 [thread overview]
Message-ID: <20190719192955.30462-2-rcampbell@nvidia.com> (raw)
In-Reply-To: <20190719192955.30462-1-rcampbell@nvidia.com>
Struct page for ZONE_DEVICE private pages uses the page->mapping and
and page->index fields while the source anonymous pages are migrated to
device private memory. This is so rmap_walk() can find the page when
migrating the ZONE_DEVICE private page back to system memory.
ZONE_DEVICE pmem backed fsdax pages also use the page->mapping and
page->index fields when files are mapped into a process address space.
Restructure struct page and add comments to make this more clear.
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/mm_types.h | 42 +++++++++++++++++++++++++++-------------
1 file changed, 29 insertions(+), 13 deletions(-)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 3a37a89eb7a7..f6c52e44d40c 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -76,13 +76,35 @@ struct page {
* avoid collision and false-positive PageTail().
*/
union {
- struct { /* Page cache and anonymous pages */
- /**
- * @lru: Pageout list, eg. active_list protected by
- * pgdat->lru_lock. Sometimes used as a generic list
- * by the page owner.
- */
- struct list_head lru;
+ struct { /* Page cache, anonymous, ZONE_DEVICE pages */
+ union {
+ /**
+ * @lru: Pageout list, e.g., active_list
+ * protected by pgdat->lru_lock. Sometimes
+ * used as a generic list by the page owner.
+ */
+ struct list_head lru;
+ /**
+ * ZONE_DEVICE pages are never on the lru
+ * list so they reuse the list space.
+ * ZONE_DEVICE private pages are counted as
+ * being mapped so the @mapping and @index
+ * fields are used while the page is migrated
+ * to device private memory.
+ * ZONE_DEVICE MEMORY_DEVICE_FS_DAX pages also
+ * use the @mapping and @index fields when pmem
+ * backed DAX files are mapped.
+ */
+ struct {
+ /**
+ * @pgmap: Points to the hosting
+ * device page map.
+ */
+ struct dev_pagemap *pgmap;
+ /** @zone_device_data: opaque data. */
+ void *zone_device_data;
+ };
+ };
/* See page-flags.h for PAGE_MAPPING_FLAGS */
struct address_space *mapping;
pgoff_t index; /* Our offset within mapping. */
@@ -155,12 +177,6 @@ struct page {
spinlock_t ptl;
#endif
};
- struct { /* ZONE_DEVICE pages */
- /** @pgmap: Points to the hosting device page map. */
- struct dev_pagemap *pgmap;
- void *zone_device_data;
- unsigned long _zd_pad_1; /* uses mapping */
- };
/** @rcu_head: You can use this to free a page by RCU. */
struct rcu_head rcu_head;
--
2.20.1
next prev parent reply other threads:[~2019-07-19 19:30 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-19 19:29 [PATCH v2 0/3] mm/hmm: fixes for device private page migration Ralph Campbell
2019-07-19 19:29 ` Ralph Campbell [this message]
2019-07-19 21:43 ` [PATCH v2 1/3] mm: document zone device struct page field usage John Hubbard
2019-07-21 15:05 ` Randy Dunlap
2019-07-21 16:02 ` Matthew Wilcox
2019-07-22 5:13 ` Ira Weiny
2019-07-22 11:08 ` Matthew Wilcox
2019-07-23 21:25 ` Ralph Campbell
2019-07-23 21:39 ` Weiny, Ira
2019-07-22 9:36 ` Christoph Hellwig
2019-07-22 9:37 ` Christoph Hellwig
2019-07-19 19:29 ` [PATCH v2 2/3] mm/hmm: fix ZONE_DEVICE anon page mapping reuse Ralph Campbell
2019-07-19 21:45 ` John Hubbard
2019-07-22 9:38 ` Christoph Hellwig
2019-07-19 19:29 ` [PATCH v2 3/3] mm/hmm: Fix bad subpage pointer in try_to_unmap_one Ralph Campbell
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