The patch titled
Subject: mm: rename _count, field of the struct page, to _refcount
has been added to the -mm tree. Its filename is
mm-rename-_count-field-of-the-struct-page-to-_refcount.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-rename-_count-field-of-the-struct-page-to-_refcount.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-rename-_count-field-of-the-struct-page-to-_refcount.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Subject: mm: rename _count, field of the struct page, to _refcount
Many developers already know that field for reference count of the struct
page is _count and atomic type. They would try to handle it directly and
this could break the purpose of page reference count tracepoint. To
prevent direct _count modification, this patch rename it to _refcount and
add warning message on the code. After that, developer who need to handle
reference count will find that field should not be accessed directly.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Sunil Goutham <sgoutham@xxxxxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/tile/mm/init.c | 2 +-
include/linux/mm_types.h | 8 ++++++--
include/linux/page_ref.h | 26 +++++++++++++-------------
kernel/kexec_core.c | 2 +-
4 files changed, 21 insertions(+), 17 deletions(-)
diff -puN arch/tile/mm/init.c~mm-rename-_count-field-of-the-struct-page-to-_refcount arch/tile/mm/init.c
--- a/arch/tile/mm/init.c~mm-rename-_count-field-of-the-struct-page-to-_refcount
+++ a/arch/tile/mm/init.c
@@ -679,7 +679,7 @@ static void __init init_free_pfn_range(u
* Hacky direct set to avoid unnecessary
* lock take/release for EVERY page here.
*/
- p->_count.counter = 0;
+ p->_refcount.counter = 0;
p->_mapcount.counter = -1;
}
init_page_count(page);
diff -puN include/linux/mm_types.h~mm-rename-_count-field-of-the-struct-page-to-_refcount include/linux/mm_types.h
--- a/include/linux/mm_types.h~mm-rename-_count-field-of-the-struct-page-to-_refcount
+++ a/include/linux/mm_types.h
@@ -97,7 +97,11 @@ struct page {
};
int units; /* SLOB */
};
- atomic_t _count; /* Usage count, see below. */
+ /*
+ * Usage count, *USE WRAPPER FUNCTION*
+ * when manual accounting. See page_ref.h
+ */
+ atomic_t _refcount;
};
unsigned int active; /* SLAB */
};
@@ -248,7 +252,7 @@ struct page_frag_cache {
__u32 offset;
#endif
/* we maintain a pagecount bias, so that we dont dirty cache line
- * containing page->_count every time we allocate a fragment.
+ * containing page->_refcount every time we allocate a fragment.
*/
unsigned int pagecnt_bias;
bool pfmemalloc;
diff -puN include/linux/page_ref.h~mm-rename-_count-field-of-the-struct-page-to-_refcount include/linux/page_ref.h
--- a/include/linux/page_ref.h~mm-rename-_count-field-of-the-struct-page-to-_refcount
+++ a/include/linux/page_ref.h
@@ -63,17 +63,17 @@ static inline void __page_ref_unfreeze(s
static inline int page_ref_count(struct page *page)
{
- return atomic_read(&page->_count);
+ return atomic_read(&page->_refcount);
}
static inline int page_count(struct page *page)
{
- return atomic_read(&compound_head(page)->_count);
+ return atomic_read(&compound_head(page)->_refcount);
}
static inline void set_page_count(struct page *page, int v)
{
- atomic_set(&page->_count, v);
+ atomic_set(&page->_refcount, v);
if (page_ref_tracepoint_active(__tracepoint_page_ref_set))
__page_ref_set(page, v);
}
@@ -89,35 +89,35 @@ static inline void init_page_count(struc
static inline void page_ref_add(struct page *page, int nr)
{
- atomic_add(nr, &page->_count);
+ atomic_add(nr, &page->_refcount);
if (page_ref_tracepoint_active(__tracepoint_page_ref_mod))
__page_ref_mod(page, nr);
}
static inline void page_ref_sub(struct page *page, int nr)
{
- atomic_sub(nr, &page->_count);
+ atomic_sub(nr, &page->_refcount);
if (page_ref_tracepoint_active(__tracepoint_page_ref_mod))
__page_ref_mod(page, -nr);
}
static inline void page_ref_inc(struct page *page)
{
- atomic_inc(&page->_count);
+ atomic_inc(&page->_refcount);
if (page_ref_tracepoint_active(__tracepoint_page_ref_mod))
__page_ref_mod(page, 1);
}
static inline void page_ref_dec(struct page *page)
{
- atomic_dec(&page->_count);
+ atomic_dec(&page->_refcount);
if (page_ref_tracepoint_active(__tracepoint_page_ref_mod))
__page_ref_mod(page, -1);
}
static inline int page_ref_sub_and_test(struct page *page, int nr)
{
- int ret = atomic_sub_and_test(nr, &page->_count);
+ int ret = atomic_sub_and_test(nr, &page->_refcount);
if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_and_test))
__page_ref_mod_and_test(page, -nr, ret);
@@ -126,7 +126,7 @@ static inline int page_ref_sub_and_test(
static inline int page_ref_dec_and_test(struct page *page)
{
- int ret = atomic_dec_and_test(&page->_count);
+ int ret = atomic_dec_and_test(&page->_refcount);
if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_and_test))
__page_ref_mod_and_test(page, -1, ret);
@@ -135,7 +135,7 @@ static inline int page_ref_dec_and_test(
static inline int page_ref_dec_return(struct page *page)
{
- int ret = atomic_dec_return(&page->_count);
+ int ret = atomic_dec_return(&page->_refcount);
if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_and_return))
__page_ref_mod_and_return(page, -1, ret);
@@ -144,7 +144,7 @@ static inline int page_ref_dec_return(st
static inline int page_ref_add_unless(struct page *page, int nr, int u)
{
- int ret = atomic_add_unless(&page->_count, nr, u);
+ int ret = atomic_add_unless(&page->_refcount, nr, u);
if (page_ref_tracepoint_active(__tracepoint_page_ref_mod_unless))
__page_ref_mod_unless(page, nr, ret);
@@ -153,7 +153,7 @@ static inline int page_ref_add_unless(st
static inline int page_ref_freeze(struct page *page, int count)
{
- int ret = likely(atomic_cmpxchg(&page->_count, count, 0) == count);
+ int ret = likely(atomic_cmpxchg(&page->_refcount, count, 0) == count);
if (page_ref_tracepoint_active(__tracepoint_page_ref_freeze))
__page_ref_freeze(page, count, ret);
@@ -165,7 +165,7 @@ static inline void page_ref_unfreeze(str
VM_BUG_ON_PAGE(page_count(page) != 0, page);
VM_BUG_ON(count == 0);
- atomic_set(&page->_count, count);
+ atomic_set(&page->_refcount, count);
if (page_ref_tracepoint_active(__tracepoint_page_ref_unfreeze))
__page_ref_unfreeze(page, count);
}
diff -puN kernel/kexec_core.c~mm-rename-_count-field-of-the-struct-page-to-_refcount kernel/kexec_core.c
--- a/kernel/kexec_core.c~mm-rename-_count-field-of-the-struct-page-to-_refcount
+++ a/kernel/kexec_core.c
@@ -1410,7 +1410,7 @@ static int __init crash_save_vmcoreinfo_
VMCOREINFO_STRUCT_SIZE(list_head);
VMCOREINFO_SIZE(nodemask_t);
VMCOREINFO_OFFSET(page, flags);
- VMCOREINFO_OFFSET(page, _count);
+ VMCOREINFO_OFFSET(page, _refcount);
VMCOREINFO_OFFSET(page, mapping);
VMCOREINFO_OFFSET(page, lru);
VMCOREINFO_OFFSET(page, _mapcount);
_
Patches currently in -mm which might be from iamjoonsoo.kim@xxxxxxx are
mm-page_ref-use-page_ref-helper-instead-of-direct-modification-of-_count.patch
mm-rename-_count-field-of-the-struct-page-to-_refcount.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
