The patch titled
Subject: mm, page_owner: add page_owner_stacks file to print out only stacks and their counte
has been added to the -mm mm-unstable branch. Its filename is
mm-page_owner-add-page_owner_stacks-file-to-print-out-only-stacks-and-their-counte.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_owner-add-page_owner_stacks-file-to-print-out-only-stacks-and-their-counte.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Oscar Salvador <osalvador@xxxxxxx>
Subject: mm, page_owner: add page_owner_stacks file to print out only stacks and their counte
Date: Tue, 16 May 2023 20:25:36 +0200
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.
Link: https://lkml.kernel.org/r/20230516182537.3139-3-osalvador@xxxxxxx
Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Waiman Long <longman@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/stackdepot.h | 6 ++
lib/stackdepot.c | 72 +++++++++++++++++++++++++++++++++++
mm/page_owner.c | 27 +++++++++++++
3 files changed, 105 insertions(+)
--- a/include/linux/stackdepot.h~mm-page_owner-add-page_owner_stacks-file-to-print-out-only-stacks-and-their-counte
+++ a/include/linux/stackdepot.h
@@ -112,6 +112,12 @@ void stack_depot_dec_count(depot_stack_h
depot_stack_handle_t stack_depot_save(unsigned long *entries,
unsigned int nr_entries, gfp_t gfp_flags);
+#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
+
/**
* stack_depot_fetch - Fetch a stack trace from stack depot
*
--- a/lib/stackdepot.c~mm-page_owner-add-page_owner_stacks-file-to-print-out-only-stacks-and-their-counte
+++ a/lib/stackdepot.c
@@ -29,6 +29,7 @@
#include <linux/types.h>
#include <linux/memblock.h>
#include <linux/kasan-enabled.h>
+#include <linux/seq_file.h>
#define DEPOT_HANDLE_BITS (sizeof(depot_stack_handle_t) * 8)
@@ -486,6 +487,77 @@ static struct stack_record *stack_depot_
return stack;
}
+#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
+
unsigned int stack_depot_fetch(depot_stack_handle_t handle,
unsigned long **entries)
{
--- a/mm/page_owner.c~mm-page_owner-add-page_owner_stacks-file-to-print-out-only-stacks-and-their-counte
+++ a/mm/page_owner.c
@@ -719,6 +719,30 @@ static const struct file_operations proc
.llseek = lseek_page_owner,
};
+static void stack_stop(struct seq_file *m, void *v)
+{
+}
+
+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)) {
@@ -729,6 +753,9 @@ static int __init pageowner_init(void)
debugfs_create_file("page_owner", 0400, NULL, NULL,
&proc_page_owner_operations);
+ debugfs_create_file("page_owner_stacks", 0400, NULL, NULL,
+ &page_owner_stack_operations);
+
return 0;
}
late_initcall(pageowner_init)
_
Patches currently in -mm which might be from osalvador@xxxxxxx are
lib-stackdepot-add-a-refcount-field-in-stack_record.patch
mm-page_owner-add-page_owner_stacks-file-to-print-out-only-stacks-and-their-counte.patch
mmpage_owner-filter-out-stacks-by-a-threshold-counter.patch
