This does not affect non ZONE_DEVICE page. In order to allow
ZONE_DEVICE page to be tracked we need to detect when refcount
of a ZONE_DEVICE page reach 1 (not 0 as non ZONE_DEVICE page).
This patch just move put_page_testzero() from put_page() to
put_zone_device_page() and only for ZONE_DEVICE. It does not
add any overhead compare to existing code.
Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
---
include/linux/mm.h | 8 +++++---
kernel/memremap.c | 2 ++
2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 5f01c88..28e8b28 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -793,11 +793,13 @@ static inline void put_page(struct page *page)
{
page = compound_head(page);
+ if (unlikely(is_zone_device_page(page))) {
+ put_zone_device_page(page);
+ return;
+ }
+
if (put_page_testzero(page))
__put_page(page);
-
- if (unlikely(is_zone_device_page(page)))
- put_zone_device_page(page);
}
#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 40d4af8..c821946 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -190,6 +190,8 @@ EXPORT_SYMBOL(get_zone_device_page);
void put_zone_device_page(struct page *page)
{
+ page_ref_dec(page);
+
put_dev_pagemap(page->pgmap);
}
EXPORT_SYMBOL(put_zone_device_page);
--
2.4.11
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