fs/proc/page: refactor to reduce code duplication

kpageflags_read() and kpagecgroup_read() are quite similar to
kpagecount_read().  Refactor common code into a helper function to reduce
code duplication.

Link: https://lkml.kernel.org/r/20250318063226.223284-1-liuyerd@163.com
Signed-off-by: Liu Ye <liuye@kylinos.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Svetly Todorov <svetly.todorov@memverge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/proc/page.c b/fs/proc/page.c
index 23fc771100ae54945d8dd782c60f3d8cf4727b37..999af26c7298552c84d53689400909219f5f1648 100644 (file)
--- 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 53364526d87756ad0e31fa20894eb5d843aa5784..5264d148bdd9d463113c836f25a674a8488c5312 100644 (file)
--- 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)