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Message-Id: <20250318063226.223284-1-liuyerd@163.com>
Date: Tue, 18 Mar 2025 14:32:26 +0800
From: Liu Ye <liuyerd@....com>
To: hannes@...xchg.org,
mhocko@...nel.org,
roman.gushchin@...ux.dev,
shakeel.butt@...ux.dev,
muchun.song@...ux.dev
Cc: akpm@...ux-foundation.org,
willy@...radead.org,
david@...hat.com,
svetly.todorov@...verge.com,
vbabka@...e.cz,
liuyerd@....com,
ran.xiaokai@....com.cn,
linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org,
cgroups@...r.kernel.org,
linux-mm@...ck.org,
Liu Ye <liuye@...inos.cn>
Subject: [PATCH v4] fs/proc/page: Refactoring to reduce code duplication.
From: Liu Ye <liuye@...inos.cn>
The function kpageflags_read and kpagecgroup_read is quite similar
to kpagecount_read. Consider refactoring common code into a helper
function to reduce code duplication.
Signed-off-by: Liu Ye <liuye@...inos.cn>
---
V4 : Update code remake patch.
V3 : Add a stub for page_cgroup_ino and remove the #ifdef CONFIG_MEMCG.
V2 : Use an enumeration to indicate the operation to be performed
to avoid passing functions.
---
---
fs/proc/page.c | 161 +++++++++++++------------------------
include/linux/memcontrol.h | 4 +
2 files changed, 58 insertions(+), 107 deletions(-)
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 23fc771100ae..999af26c7298 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -22,6 +22,12 @@
#define KPMMASK (KPMSIZE - 1)
#define KPMBITS (KPMSIZE * BITS_PER_BYTE)
+enum kpage_operation {
+ KPAGE_FLAGS,
+ KPAGE_COUNT,
+ KPAGE_CGROUP,
+};
+
static inline unsigned long get_max_dump_pfn(void)
{
#ifdef CONFIG_SPARSEMEM
@@ -37,19 +43,17 @@ static inline unsigned long get_max_dump_pfn(void)
#endif
}
-/* /proc/kpagecount - an array exposing page mapcounts
- *
- * Each entry is a u64 representing the corresponding
- * physical page mapcount.
- */
-static ssize_t kpagecount_read(struct file *file, char __user *buf,
- size_t count, loff_t *ppos)
+static ssize_t kpage_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos,
+ enum kpage_operation op)
{
const unsigned long max_dump_pfn = get_max_dump_pfn();
u64 __user *out = (u64 __user *)buf;
+ struct page *page;
unsigned long src = *ppos;
unsigned long pfn;
ssize_t ret = 0;
+ u64 info;
pfn = src / KPMSIZE;
if (src & KPMMASK || count & KPMMASK)
@@ -59,24 +63,34 @@ static ssize_t kpagecount_read(struct file *file, char __user *buf,
count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
while (count > 0) {
- struct page *page;
- u64 mapcount = 0;
-
/*
* TODO: ZONE_DEVICE support requires to identify
* memmaps that were actually initialized.
*/
page = pfn_to_online_page(pfn);
- if (page) {
- struct folio *folio = page_folio(page);
- if (IS_ENABLED(CONFIG_PAGE_MAPCOUNT))
- mapcount = folio_precise_page_mapcount(folio, page);
- else
- mapcount = folio_average_page_mapcount(folio);
- }
-
- if (put_user(mapcount, out)) {
+ if (page) {
+ switch (op) {
+ case KPAGE_FLAGS:
+ info = stable_page_flags(page);
+ break;
+ case KPAGE_COUNT:
+ if (IS_ENABLED(CONFIG_PAGE_MAPCOUNT))
+ info = folio_precise_page_mapcount(page_folio(page), page);
+ else
+ info = folio_average_page_mapcount(page_folio(page));
+ break;
+ case KPAGE_CGROUP:
+ info = page_cgroup_ino(page);
+ break;
+ default:
+ info = 0;
+ break;
+ }
+ } else
+ info = 0;
+
+ if (put_user(info, out)) {
ret = -EFAULT;
break;
}
@@ -94,17 +108,23 @@ static ssize_t kpagecount_read(struct file *file, char __user *buf,
return ret;
}
+/* /proc/kpagecount - an array exposing page mapcounts
+ *
+ * Each entry is a u64 representing the corresponding
+ * physical page mapcount.
+ */
+static ssize_t kpagecount_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ return kpage_read(file, buf, count, ppos, KPAGE_COUNT);
+}
+
static const struct proc_ops kpagecount_proc_ops = {
.proc_flags = PROC_ENTRY_PERMANENT,
.proc_lseek = mem_lseek,
.proc_read = kpagecount_read,
};
-/* /proc/kpageflags - an array exposing page flags
- *
- * Each entry is a u64 representing the corresponding
- * physical page flags.
- */
static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
{
@@ -225,47 +245,17 @@ u64 stable_page_flags(const struct page *page)
#endif
return u;
-};
+}
+/* /proc/kpageflags - an array exposing page flags
+ *
+ * Each entry is a u64 representing the corresponding
+ * physical page flags.
+ */
static ssize_t kpageflags_read(struct file *file, char __user *buf,
- size_t count, loff_t *ppos)
+ size_t count, loff_t *ppos)
{
- const unsigned long max_dump_pfn = get_max_dump_pfn();
- u64 __user *out = (u64 __user *)buf;
- unsigned long src = *ppos;
- unsigned long pfn;
- ssize_t ret = 0;
-
- pfn = src / KPMSIZE;
- if (src & KPMMASK || count & KPMMASK)
- return -EINVAL;
- if (src >= max_dump_pfn * KPMSIZE)
- return 0;
- count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
-
- while (count > 0) {
- /*
- * TODO: ZONE_DEVICE support requires to identify
- * memmaps that were actually initialized.
- */
- struct page *page = pfn_to_online_page(pfn);
-
- if (put_user(stable_page_flags(page), out)) {
- ret = -EFAULT;
- break;
- }
-
- pfn++;
- out++;
- count -= KPMSIZE;
-
- cond_resched();
- }
-
- *ppos += (char __user *)out - buf;
- if (!ret)
- ret = (char __user *)out - buf;
- return ret;
+ return kpage_read(file, buf, count, ppos, KPAGE_FLAGS);
}
static const struct proc_ops kpageflags_proc_ops = {
@@ -276,53 +266,10 @@ static const struct proc_ops kpageflags_proc_ops = {
#ifdef CONFIG_MEMCG
static ssize_t kpagecgroup_read(struct file *file, char __user *buf,
- size_t count, loff_t *ppos)
+ size_t count, loff_t *ppos)
{
- const unsigned long max_dump_pfn = get_max_dump_pfn();
- u64 __user *out = (u64 __user *)buf;
- struct page *ppage;
- unsigned long src = *ppos;
- unsigned long pfn;
- ssize_t ret = 0;
- u64 ino;
-
- pfn = src / KPMSIZE;
- if (src & KPMMASK || count & KPMMASK)
- return -EINVAL;
- if (src >= max_dump_pfn * KPMSIZE)
- return 0;
- count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
-
- while (count > 0) {
- /*
- * TODO: ZONE_DEVICE support requires to identify
- * memmaps that were actually initialized.
- */
- ppage = pfn_to_online_page(pfn);
-
- if (ppage)
- ino = page_cgroup_ino(ppage);
- else
- ino = 0;
-
- if (put_user(ino, out)) {
- ret = -EFAULT;
- break;
- }
-
- pfn++;
- out++;
- count -= KPMSIZE;
-
- cond_resched();
- }
-
- *ppos += (char __user *)out - buf;
- if (!ret)
- ret = (char __user *)out - buf;
- return ret;
+ return kpage_read(file, buf, count, ppos, KPAGE_CGROUP);
}
-
static const struct proc_ops kpagecgroup_proc_ops = {
.proc_flags = PROC_ENTRY_PERMANENT,
.proc_lseek = mem_lseek,
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 53364526d877..5264d148bdd9 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1793,6 +1793,10 @@ static inline void count_objcg_events(struct obj_cgroup *objcg,
{
}
+static inline ino_t page_cgroup_ino(struct page *page)
+{
+ return 0;
+}
#endif /* CONFIG_MEMCG */
#if defined(CONFIG_MEMCG) && defined(CONFIG_ZSWAP)
--
2.25.1
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