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Date: Fri, 4 Nov 2022 10:33:53 +0100
From: Oscar Salvador <osalvador@...e.de>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Michal Hocko <mhocko@...e.com>,
Vlastimil Babka <vbabka@...e.cz>,
Eric Dumazet <edumazet@...gle.com>,
Waiman Long <longman@...hat.com>,
Suren Baghdasaryan <surenb@...gle.com>,
Marco Elver <elver@...gle.com>,
Andrey Konovalov <andreyknvl@...il.com>,
Alexander Potapenko <glider@...gle.com>,
Oscar Salvador <osalvador@...e.de>
Subject: [PATCH v3 2/3] mm, page_owner: Add page_owner_stacks file to print out only stacks and their counte
We might be only interested in knowing about stacks <-> count
relationship, so instead of having to fiddle with page_owner
output and screen through pfns, let us add a new file called
'page_owner_stacks' that does just that.
By cating such file, we will get all the stacktraces followed by
its counter, so we can have a more global view.
Signed-off-by: Oscar Salvador <osalvador@...e.de
---
include/linux/stackdepot.h | 5 +++
lib/stackdepot.c | 73 ++++++++++++++++++++++++++++++++++++++
mm/page_owner.c | 29 +++++++++++++++
3 files changed, 107 insertions(+)
diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h
index 4e3a88f135ee..ca048a79bf7c 100644
--- a/include/linux/stackdepot.h
+++ b/include/linux/stackdepot.h
@@ -66,6 +66,11 @@ depot_stack_handle_t stack_depot_save_action(unsigned long *entries,
unsigned int nr_entries,
gfp_t gfp_flags,
enum stack_depot_action action);
+#ifdef CONFIG_PAGE_OWNER
+void *stack_start(struct seq_file *m, loff_t *ppos);
+void *stack_next(struct seq_file *m, void *v, loff_t *ppos);
+int stack_print(struct seq_file *m, void *v);
+#endif
unsigned int stack_depot_fetch(depot_stack_handle_t handle,
unsigned long **entries);
diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index a806ef58a385..97e5dce40f4b 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -33,6 +33,8 @@
#include <linux/types.h>
#include <linux/memblock.h>
#include <linux/kasan-enabled.h>
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
#define DEPOT_STACK_BITS (sizeof(depot_stack_handle_t) * 8)
@@ -565,3 +567,74 @@ depot_stack_handle_t stack_depot_save_action(unsigned long *entries,
return __stack_depot_save(entries, nr_entries, alloc_flags, true, action);
}
EXPORT_SYMBOL_GPL(stack_depot_save_action);
+
+#ifdef CONFIG_PAGE_OWNER
+void *stack_start(struct seq_file *m, loff_t *ppos)
+{
+ unsigned long *table = m->private;
+ struct stack_record **stacks, *stack;
+
+ /* First time */
+ if (*ppos == 0)
+ *table = 0;
+
+ if (*ppos == -1UL)
+ return NULL;
+
+ stacks = &stack_table[*table];
+ stack = (struct stack_record *)stacks;
+
+ return stack;
+}
+
+void *stack_next(struct seq_file *m, void *v, loff_t *ppos)
+{
+ unsigned long *table = m->private;
+ unsigned long nr_table = *table;
+ struct stack_record *next = NULL, *stack = v, **stacks;
+ unsigned long stack_table_entries = stack_hash_mask + 1;
+
+ if (!stack) {
+new_table:
+ /* New table */
+ nr_table++;
+ if (nr_table >= stack_table_entries)
+ goto out;
+ stacks = &stack_table[nr_table];
+ stack = (struct stack_record *)stacks;
+ next = stack;
+ } else {
+ next = stack->next;
+ }
+
+ if (!next)
+ goto new_table;
+
+out:
+ *table = nr_table;
+ *ppos = (nr_table >= stack_table_entries) ? -1UL : *ppos + 1;
+ return next;
+}
+
+int stack_print(struct seq_file *m, void *v)
+{
+ char *buf;
+ int ret = 0;
+ struct stack_record *stack =v;
+
+ if (!stack->size || stack->size < 0 ||
+ stack->size > PAGE_SIZE || stack->handle.valid != 1 ||
+ refcount_read(&stack->count) < 1)
+ return 0;
+
+ buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+ ret += stack_trace_snprint(buf, PAGE_SIZE, stack->entries, stack->size, 0);
+ scnprintf(buf + ret, PAGE_SIZE - ret, "stack count: %d\n\n",
+ refcount_read(&stack->count));
+ seq_printf(m, buf);
+ seq_puts(m, "\n\n");
+ kfree(buf);
+
+ return 0;
+}
+#endif
diff --git a/mm/page_owner.c b/mm/page_owner.c
index 8730f377fa91..3808c0985060 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -668,6 +668,32 @@ static const struct file_operations proc_page_owner_operations = {
.read = read_page_owner,
};
+static void stack_stop(struct seq_file *m, void *v)
+{
+ return;
+}
+
+static const struct seq_operations page_owner_stack_op = {
+ .start = stack_start,
+ .next = stack_next,
+ .stop = stack_stop,
+ .show = stack_print
+};
+
+static int page_owner_stack_open(struct inode *inode, struct file *file)
+{
+ return seq_open_private(file, &page_owner_stack_op,
+ sizeof(unsigned long));
+}
+
+
+const struct file_operations page_owner_stack_operations = {
+ .open = page_owner_stack_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
static int __init pageowner_init(void)
{
if (!static_branch_unlikely(&page_owner_inited)) {
@@ -678,6 +704,9 @@ static int __init pageowner_init(void)
debugfs_create_file("page_owner", 0400, NULL, NULL,
&proc_page_owner_operations);
+ debugfs_create_file("page_owner_stacks", S_IRUSR, NULL, NULL,
+ &page_owner_stack_operations);
+
return 0;
}
late_initcall(pageowner_init)
--
2.35.3
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