From e337e1078ddbf3844a7e2e2ea8340d08b02ed6c8 Mon Sep 17 00:00:00 2001
From: Imran Khan <imran.f.khan@oracle.com>
Date: Mon, 8 Nov 2021 18:33:12 -0800
Subject: lib, stackdepot: add helper to print stack entries
Git-commit: 505be48165fa2f2cb795659b4fc61f35563d105e
Patch-mainline: v5.16-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

To print a stack entries, users of stackdepot, first use stack_depot_fetch
to get a list of stack entries and then use stack_trace_print to print
this list.  Provide a helper in stackdepot to print stack entries based on
stackdepot handle.  Also change above mentioned users to use this helper.

Link: https://lkml.kernel.org/r/20210915014806.3206938-3-imran.f.khan@oracle.com
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 include/linux/stackdepot.h |  2 ++
 lib/stackdepot.c           | 18 ++++++++++++++++++
 mm/kasan/report.c          | 15 +++------------
 mm/page_owner.c            | 13 ++++---------
 4 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h
index 6bb4bc1a5f54..a144cf0000ff 100644
--- a/include/linux/stackdepot.h
+++ b/include/linux/stackdepot.h
@@ -21,6 +21,8 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle,
 
 unsigned int filter_irq_stacks(unsigned long *entries, unsigned int nr_entries);
 
+void stack_depot_print(depot_stack_handle_t stack);
+
 #ifdef CONFIG_STACKDEPOT
 int stack_depot_init(void);
 #else
diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 0a2e417f83cb..4b82cf33d620 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -214,6 +214,24 @@ static inline struct stack_record *find_stack(struct stack_record *bucket,
 	return NULL;
 }
 
+/**
+ * stack_depot_print - print stack entries from a depot
+ *
+ * @stack:		Stack depot handle which was returned from
+ *			stack_depot_save().
+ *
+ */
+void stack_depot_print(depot_stack_handle_t stack)
+{
+	unsigned long *entries;
+	unsigned int nr_entries;
+
+	nr_entries = stack_depot_fetch(stack, &entries);
+	if (nr_entries > 0)
+		stack_trace_print(entries, nr_entries, 0);
+}
+EXPORT_SYMBOL_GPL(stack_depot_print);
+
 /**
  * stack_depot_fetch - Fetch stack entries from a depot
  *
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 8fff1825b22c..6bc86c9fd59f 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -109,20 +109,11 @@ static void end_report(unsigned long *flags, unsigned long addr)
 	kasan_enable_current();
 }
 
-static void print_stack(depot_stack_handle_t stack)
-{
-	unsigned long *entries;
-	unsigned int nr_entries;
-
-	nr_entries = stack_depot_fetch(stack, &entries);
-	stack_trace_print(entries, nr_entries, 0);
-}
-
 static void print_track(struct kasan_track *track, const char *prefix)
 {
 	pr_err("%s by task %u:\n", prefix, track->pid);
 	if (track->stack) {
-		print_stack(track->stack);
+		stack_depot_print(track->stack);
 	} else {
 		pr_err("(stack is not available)\n");
 	}
@@ -191,12 +182,12 @@ static void describe_object_stacks(struct kmem_cache *cache, void *object,
 		return;
 	if (alloc_meta->aux_stack[0]) {
 		pr_err("Last potentially related work creation:\n");
-		print_stack(alloc_meta->aux_stack[0]);
+		stack_depot_print(alloc_meta->aux_stack[0]);
 		pr_err("\n");
 	}
 	if (alloc_meta->aux_stack[1]) {
 		pr_err("Second to last potentially related work creation:\n");
-		print_stack(alloc_meta->aux_stack[1]);
+		stack_depot_print(alloc_meta->aux_stack[1]);
 		pr_err("\n");
 	}
 #endif
diff --git a/mm/page_owner.c b/mm/page_owner.c
index f51a57e92aa3..d30aa04dd8a4 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -397,8 +397,6 @@ void __dump_page_owner(const struct page *page)
 	struct page_ext *page_ext = lookup_page_ext(page);
 	struct page_owner *page_owner;
 	depot_stack_handle_t handle;
-	unsigned long *entries;
-	unsigned int nr_entries;
 	gfp_t gfp_mask;
 	int mt;
 
@@ -426,20 +424,17 @@ void __dump_page_owner(const struct page *page)
 		 page_owner->pid, page_owner->ts_nsec, page_owner->free_ts_nsec);
 
 	handle = READ_ONCE(page_owner->handle);
-	if (!handle) {
+	if (!handle)
 		pr_alert("page_owner allocation stack trace missing\n");
-	} else {
-		nr_entries = stack_depot_fetch(handle, &entries);
-		stack_trace_print(entries, nr_entries, 0);
-	}
+	else
+		stack_depot_print(handle);
 
 	handle = READ_ONCE(page_owner->free_handle);
 	if (!handle) {
 		pr_alert("page_owner free stack trace missing\n");
 	} else {
-		nr_entries = stack_depot_fetch(handle, &entries);
 		pr_alert("page last free stack trace:\n");
-		stack_trace_print(entries, nr_entries, 0);
+		stack_depot_print(handle);
 	}
 
 	if (page_owner->last_migrate_reason != -1)
-- 
2.38.1