1 files changed, 82 insertions, 125 deletions

diff --git a/fs/proc/page.c b/fs/proc/page.c
index 23fc771100ae..ba3568e97fd1 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 +43,33 @@ 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 u64 get_kpage_count(const struct page *page)
+{
+	struct page_snapshot ps;
+	u64 ret;
+
+	snapshot_page(&ps, page);
+
+	if (IS_ENABLED(CONFIG_PAGE_MAPCOUNT))
+		ret = folio_precise_page_mapcount(&ps.folio_snapshot,
+						  &ps.page_snapshot);
+	else
+		ret = folio_average_page_mapcount(&ps.folio_snapshot);
+
+	return ret;
+}
+
+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 +79,31 @@ 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:
+				info = get_kpage_count(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 +121,23 @@ 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)
 {
@@ -114,6 +147,7 @@ static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
 u64 stable_page_flags(const struct page *page)
 {
 	const struct folio *folio;
+	struct page_snapshot ps;
 	unsigned long k;
 	unsigned long mapping;
 	bool is_anon;
@@ -125,20 +159,22 @@ u64 stable_page_flags(const struct page *page)
 	 */
 	if (!page)
 		return 1 << KPF_NOPAGE;
-	folio = page_folio(page);
+
+	snapshot_page(&ps, page);
+	folio = &ps.folio_snapshot;
 
 	k = folio->flags;
 	mapping = (unsigned long)folio->mapping;
-	is_anon = mapping & PAGE_MAPPING_ANON;
+	is_anon = mapping & FOLIO_MAPPING_ANON;
 
 	/*
 	 * pseudo flags for the well known (anonymous) memory mapped pages
 	 */
-	if (page_mapped(page))
+	if (folio_mapped(folio))
 		u |= 1 << KPF_MMAP;
 	if (is_anon) {
 		u |= 1 << KPF_ANON;
-		if (mapping & PAGE_MAPPING_KSM)
+		if (mapping & FOLIO_MAPPING_KSM)
 			u |= 1 << KPF_KSM;
 	}
 
@@ -146,7 +182,7 @@ u64 stable_page_flags(const struct page *page)
 	 * compound pages: export both head/tail info
 	 * they together define a compound page's start/end pos and order
 	 */
-	if (page == &folio->page)
+	if (ps.idx == 0)
 		u |= kpf_copy_bit(k, KPF_COMPOUND_HEAD, PG_head);
 	else
 		u |= 1 << KPF_COMPOUND_TAIL;
@@ -156,25 +192,19 @@ u64 stable_page_flags(const struct page *page)
 	         folio_test_large_rmappable(folio)) {
 		/* Note: we indicate any THPs here, not just PMD-sized ones */
 		u |= 1 << KPF_THP;
-	} else if (is_huge_zero_folio(folio)) {
+	} else if (is_huge_zero_pfn(ps.pfn)) {
 		u |= 1 << KPF_ZERO_PAGE;
 		u |= 1 << KPF_THP;
-	} else if (is_zero_folio(folio)) {
+	} else if (is_zero_pfn(ps.pfn)) {
 		u |= 1 << KPF_ZERO_PAGE;
 	}
 
-	/*
-	 * Caveats on high order pages: PG_buddy and PG_slab will only be set
-	 * on the head page.
-	 */
-	if (PageBuddy(page))
-		u |= 1 << KPF_BUDDY;
-	else if (page_count(page) == 0 && is_free_buddy_page(page))
+	if (ps.flags & PAGE_SNAPSHOT_PG_BUDDY)
 		u |= 1 << KPF_BUDDY;
 
-	if (PageOffline(page))
+	if (folio_test_offline(folio))
 		u |= 1 << KPF_OFFLINE;
-	if (PageTable(page))
+	if (folio_test_pgtable(folio))
 		u |= 1 << KPF_PGTABLE;
 	if (folio_test_slab(folio))
 		u |= 1 << KPF_SLAB;
@@ -182,7 +212,7 @@ u64 stable_page_flags(const struct page *page)
 #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
 	u |= kpf_copy_bit(k, KPF_IDLE,          PG_idle);
 #else
-	if (folio_test_idle(folio))
+	if (ps.flags & PAGE_SNAPSHOT_PG_IDLE)
 		u |= 1 << KPF_IDLE;
 #endif
 
@@ -208,7 +238,7 @@ u64 stable_page_flags(const struct page *page)
 	if (u & (1 << KPF_HUGE))
 		u |= kpf_copy_bit(k, KPF_HWPOISON,	PG_hwpoison);
 	else
-		u |= kpf_copy_bit(page->flags, KPF_HWPOISON,	PG_hwpoison);
+		u |= kpf_copy_bit(ps.page_snapshot.flags, KPF_HWPOISON, PG_hwpoison);
 #endif
 
 	u |= kpf_copy_bit(k, KPF_RESERVED,	PG_reserved);
@@ -225,47 +255,17 @@ 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 +276,10 @@ 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,