+ mm-page_owner-add-print_mode-filter.patch added to mm-new branch

+ mm-page_owner-add-print_mode-filter.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm/page_owner: add print_mode filter
has been added to the -mm mm-new branch.  Its filename is
     mm-page_owner-add-print_mode-filter.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-print_mode-filter.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days

------------------------------------------------------
From: Zhen Ni <zhen.ni@easystack.cn>
Subject: mm/page_owner: add print_mode filter
Date: Sun, 19 Apr 2026 23:55:39 +0800

Add print_mode functionality to reduce page_owner output size by printing
only the stack handle instead of the full stack trace.

Example output with print_mode enabled:
  Page allocated via order 0, mask 0x42800(GFP_NOWAIT|__GFP_COMP),
  pid 1, tgid 1 (systemd), ts 349667370 ns
  PFN 0xa00a2 type Unmovable Block 1280 type Unmovable
  Flags 0x33fffe0000004124(referenced|lru|active|private|node=3|zone=0|
lastcpupid=0x1ffff)
  handle: 17432583
  Charged to memcg /

Print mode significantly reduces output size while preserving all other
page allocation information.  The correspondence between handles and stack
traces can be obtained through the show_stacks_handles interface.

Link: https://lore.kernel.org/linux-mm/20260417154638.22370-3-zhen.ni@easystack.cn/
Link: https://lore.kernel.org/20260419155540.376847-3-zhen.ni@easystack.cn
Signed-off-by: Zhen Ni <zhen.ni@easystack.cn>
Suggested-by: Zi Yan <ziy@nvidia.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_owner.c |   28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

--- a/mm/page_owner.c~mm-page_owner-add-print_mode-filter
+++ a/mm/page_owner.c
@@ -590,7 +590,13 @@ print_page_owner(char __user *buf, size_
 			migratetype_names[pageblock_mt],
 			&page->flags);
 
-	ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0);
+	/* Print mode: full stack or stack handle */
+	if (READ_ONCE(owner_filter.print_mode) == PAGE_OWNER_PRINT_STACK_HANDLE) {
+		ret += scnprintf(kbuf + ret, count - ret,
+				"handle: %d\n", handle);
+	} else {
+		ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0);
+	}
 	if (ret >= count)
 		goto err;
 
@@ -985,6 +991,24 @@ static int page_owner_threshold_set(void
 DEFINE_SIMPLE_ATTRIBUTE(page_owner_threshold_fops, &page_owner_threshold_get,
 			&page_owner_threshold_set, "%llu");
 
+static int page_owner_print_mode_get(void *data, u64 *val)
+{
+	*val = READ_ONCE(owner_filter.print_mode);
+	return 0;
+}
+
+static int page_owner_print_mode_set(void *data, u64 val)
+{
+	if (val > PAGE_OWNER_PRINT_STACK_HANDLE)
+		return -EINVAL;
+	WRITE_ONCE(owner_filter.print_mode, val);
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(page_owner_print_mode_fops,
+			&page_owner_print_mode_get,
+			&page_owner_print_mode_set, "%lld");
+
 
 static int __init pageowner_init(void)
 {
@@ -998,6 +1022,8 @@ static int __init pageowner_init(void)
 	debugfs_create_file("page_owner", 0400, NULL, NULL, &page_owner_fops);
 
 	filter_dir = debugfs_create_dir("page_owner_filter", NULL);
+	debugfs_create_file("print_mode", 0600, filter_dir, NULL,
+			    &page_owner_print_mode_fops);
 
 	dir = debugfs_create_dir("page_owner_stacks", NULL);
 	debugfs_create_file("show_stacks", 0400, dir,
_

Patches currently in -mm which might be from zhen.ni@easystack.cn are

mm-page_owner-add-filter-infrastructure.patch
mm-page_owner-add-print_mode-filter.patch
mm-page_owner-add-numa-node-filter-with-nodelist-support.patch

+ mm-page_owner-add-print_mode-filter.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm/page_owner: add print_mode filter
has been added to the -mm mm-new branch.  Its filename is
     mm-page_owner-add-print_mode-filter.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-print_mode-filter.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days

------------------------------------------------------
From: Zhen Ni <zhen.ni@easystack.cn>
Subject: mm/page_owner: add print_mode filter
Date: Tue, 28 Apr 2026 15:11:10 +0800

Add print_mode functionality to reduce page_owner output size by printing
only the stack handle instead of the full stack trace.

Example output with print_mode enabled:
  Page allocated via order 0, mask 0x42800(GFP_NOWAIT|__GFP_COMP),
  pid 1, tgid 1 (systemd), ts 349667370 ns
  PFN 0xa00a2 type Unmovable Block 1280 type Unmovable
  Flags 0x33fffe0000004124(referenced|lru|active|private|node=3|zone=0|
lastcpupid=0x1ffff)
  handle: 17432583
  Charged to memcg /

Print mode significantly reduces output size while preserving all other
page allocation information.  The correspondence between handles and stack
traces can be obtained through the show_stacks_handles interface.

Link: https://lore.kernel.org/linux-mm/20260417154638.22370-3-zhen.ni@easystack.cn/
Link: https://lore.kernel.org/20260428071112.1420380-3-zhen.ni@easystack.cn
Signed-off-by: Zhen Ni <zhen.ni@easystack.cn>
Suggested-by: Zi Yan <ziy@nvidia.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_owner.c |   28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

--- a/mm/page_owner.c~mm-page_owner-add-print_mode-filter
+++ a/mm/page_owner.c
@@ -590,7 +590,13 @@ print_page_owner(char __user *buf, size_
 			migratetype_names[pageblock_mt],
 			&page->flags);
 
-	ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0);
+	/* Print mode: full stack or stack handle */
+	if (READ_ONCE(owner_filter.print_mode) == PAGE_OWNER_PRINT_STACK_HANDLE) {
+		ret += scnprintf(kbuf + ret, count - ret,
+				"handle: %d\n", handle);
+	} else {
+		ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0);
+	}
 	if (ret >= count)
 		goto err;
 
@@ -985,6 +991,24 @@ static int page_owner_threshold_set(void
 DEFINE_SIMPLE_ATTRIBUTE(page_owner_threshold_fops, &page_owner_threshold_get,
 			&page_owner_threshold_set, "%llu");
 
+static int page_owner_print_mode_get(void *data, u64 *val)
+{
+	*val = READ_ONCE(owner_filter.print_mode);
+	return 0;
+}
+
+static int page_owner_print_mode_set(void *data, u64 val)
+{
+	if (val > PAGE_OWNER_PRINT_STACK_HANDLE)
+		return -EINVAL;
+	WRITE_ONCE(owner_filter.print_mode, val);
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(page_owner_print_mode_fops,
+			&page_owner_print_mode_get,
+			&page_owner_print_mode_set, "%lld");
+
 
 static int __init pageowner_init(void)
 {
@@ -998,6 +1022,8 @@ static int __init pageowner_init(void)
 	debugfs_create_file("page_owner", 0400, NULL, NULL, &page_owner_fops);
 
 	filter_dir = debugfs_create_dir("page_owner_filter", NULL);
+	debugfs_create_file("print_mode", 0600, filter_dir, NULL,
+			    &page_owner_print_mode_fops);
 
 	dir = debugfs_create_dir("page_owner_stacks", NULL);
 	debugfs_create_file("show_stacks", 0400, dir,
_

Patches currently in -mm which might be from zhen.ni@easystack.cn are

mm-page_owner-add-filter-infrastructure.patch
mm-page_owner-add-print_mode-filter.patch
mm-page_owner-add-numa-node-filter-with-nodelist-support.patch
mm-page_owner-document-page_owner-filter-features.patch
mm-page_owner-fix-%pgp-format-specifier-argument-type.patch

+ mm-page_owner-add-print_mode-filter.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm/page_owner: add print_mode filter
has been added to the -mm mm-new branch.  Its filename is
     mm-page_owner-add-print_mode-filter.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-print_mode-filter.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days

------------------------------------------------------
From: Zhen Ni <zhen.ni@easystack.cn>
Subject: mm/page_owner: add print_mode filter
Date: Thu, 25 Jun 2026 12:30:58 +0800

Patch series "mm/page_owner: add per-fd filter infrastructure for
print_mode and NUMA filtering", v11.

This patch series introduces per-file-descriptor filtering capabilities to the
page_owner feature.


This patch (of 4):

Add a print_mode filter to page_owner that allows users to choose between
printing stack traces, stack handles, or both, providing flexibility for
different debugging and analysis scenarios.

The filter provides three modes via page_owner:
- Writing "mode=stack" prints stack traces for each page (default)
- Writing "mode=handle" prints only the handle number
- Writing "mode=stack_handle" prints both stack traces and handles

The default stack mode maintains backward compatibility with existing
usage, displaying complete stack traces for each page allocation.

The handle mode dramatically reduces log size and improves performance by
showing only the handle number instead of the full stack trace.  Testing
shows handle mode reduces output size by ~66% (84MB vs 244MB) and improves
read performance by ~4.4x compared to full stack output.  The mapping from
handles to actual stack traces can be obtained via the show_stacks_handles
interface.

The stack_handle mode prints both stack traces and handles, making it
easier to identify pages with the same allocation pattern by comparing
handle numbers instead of comparing large stack traces.

Example usage:
  # Using the page_owner_filter tool (recommended)
  ./page_owner_filter -m stack          # Print only stack traces (default)
  ./page_owner_filter -m handle         # Print only handles
  ./page_owner_filter -m stack_handle   # Print both stack and handles

Sample output (handle mode):
  Page allocated via order 0, migratetype Unmovable, gfp_mask 0x1100ca,
  pid 1, tgid 1 (systemd), ts 123456789 ns
  PFN 0x1000 type Unmovable Block 1 type Unmovable
  Flags 0x3fffe800000084(referenced|lru|active|private|node=0|zone=1)
  handle: 17432583
  ...

This implementation uses per-file-descriptor filter state stored in
file->private_data, allowing each opener to have independent filter
configuration.

Link: https://lore.kernel.org/20260625043101.338794-1-zhen.ni@easystack.cn
Link: https://lore.kernel.org/20260625043101.338794-2-zhen.ni@easystack.cn
Signed-off-by: Zhen Ni <zhen.ni@easystack.cn>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yichong Chen <chenyichong@uniontech.com>
Cc: Ye Liu <ye.liu@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_owner.c |  129 +++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 123 insertions(+), 6 deletions(-)

--- a/mm/page_owner.c~mm-page_owner-add-print_mode-filter
+++ a/mm/page_owner.c
@@ -61,6 +61,23 @@ struct stack_print_ctx {
 	u8 flags;
 };
 
+enum page_owner_print_mode {
+	PAGE_OWNER_PRINT_STACK,
+	PAGE_OWNER_PRINT_HANDLE,
+	PAGE_OWNER_PRINT_STACK_HANDLE,
+};
+
+static const char * const page_owner_print_mode_strings[] = {
+	[PAGE_OWNER_PRINT_STACK]	= "stack",
+	[PAGE_OWNER_PRINT_HANDLE]	= "handle",
+	[PAGE_OWNER_PRINT_STACK_HANDLE]	= "stack_handle",
+};
+
+struct page_owner_filter_state {
+	enum page_owner_print_mode print_mode;
+	spinlock_t lock;
+};
+
 static bool page_owner_enabled __initdata;
 DEFINE_STATIC_KEY_FALSE(page_owner_inited);
 
@@ -587,16 +604,23 @@ static inline int print_page_owner_memcg
 static ssize_t
 print_page_owner(char __user *buf, size_t count, unsigned long pfn,
 		struct page *page, struct page_owner *page_owner,
-		depot_stack_handle_t handle)
+		depot_stack_handle_t handle,
+		struct page_owner_filter_state *state)
 {
 	int ret, pageblock_mt, page_mt;
 	char *kbuf;
+	enum page_owner_print_mode print_mode;
+	unsigned long flags;
 
 	count = min_t(size_t, count, PAGE_SIZE);
 	kbuf = kmalloc(count, GFP_KERNEL);
 	if (!kbuf)
 		return -ENOMEM;
 
+	spin_lock_irqsave(&state->lock, flags);
+	print_mode = state->print_mode;
+	spin_unlock_irqrestore(&state->lock, flags);
+
 	ret = scnprintf(kbuf, count,
 			"Page allocated via order %u, mask %#x(%pGg), pid %d, tgid %d (%s), ts %llu ns\n",
 			page_owner->order, page_owner->gfp_mask,
@@ -615,9 +639,18 @@ print_page_owner(char __user *buf, size_
 			migratetype_names[pageblock_mt],
 			&page->flags.f);
 
-	ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0);
-	if (ret >= count)
-		goto err;
+	if (print_mode != PAGE_OWNER_PRINT_HANDLE) {
+		ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0);
+		if (ret >= count)
+			goto err;
+	}
+
+	if (print_mode != PAGE_OWNER_PRINT_STACK) {
+		ret += scnprintf(kbuf + ret, count - ret, "handle: %u\n",
+				 handle);
+		if (ret >= count)
+			goto err;
+	}
 
 	if (page_owner->last_migrate_reason != MIGRATE_REASON_NONE) {
 		ret += scnprintf(kbuf + ret, count - ret,
@@ -705,6 +738,7 @@ read_page_owner(struct file *file, char
 	struct page_ext *page_ext;
 	struct page_owner *page_owner;
 	depot_stack_handle_t handle;
+	struct page_owner_filter_state *state = file->private_data;
 
 	if (!static_branch_unlikely(&page_owner_inited))
 		return -EINVAL;
@@ -782,7 +816,7 @@ read_page_owner(struct file *file, char
 		page_owner_tmp = *page_owner;
 		page_ext_put(page_ext);
 		return print_page_owner(buf, count, pfn, page,
-				&page_owner_tmp, handle);
+				&page_owner_tmp, handle, state);
 ext_put_continue:
 		page_ext_put(page_ext);
 	}
@@ -871,7 +905,90 @@ static void init_early_allocated_pages(v
 		init_pages_in_zone(zone);
 }
 
+static int page_owner_open(struct inode *inode, struct file *file)
+{
+	struct page_owner_filter_state *state;
+
+	state = kzalloc_obj(*state);
+	if (!state)
+		return -ENOMEM;
+
+	spin_lock_init(&state->lock);
+	state->print_mode = PAGE_OWNER_PRINT_STACK;
+	file->private_data = state;
+	return 0;
+}
+
+static int page_owner_release(struct inode *inode, struct file *file)
+{
+	kfree(file->private_data);
+	return 0;
+}
+
+static ssize_t page_owner_write(struct file *file,
+				 const char __user *buf,
+				 size_t count, loff_t *ppos)
+{
+	char *kbuf;
+	char *orig;
+	char *token;
+	int ret;
+	size_t max_input_len;
+	struct page_owner_filter_state *state = file->private_data;
+	enum page_owner_print_mode new_print_mode;
+	unsigned long flags;
+
+	/*
+	 * Maximum input length for filter commands:
+	 * 32: print_mode command max length is 17 ("mode=stack_handle").
+	 */
+	max_input_len = 32;
+
+	if (count > max_input_len)
+		return -EINVAL;
+
+	kbuf = memdup_user_nul(buf, count);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
+
+	orig = kbuf;
+
+	spin_lock_irqsave(&state->lock, flags);
+	new_print_mode = state->print_mode;
+	spin_unlock_irqrestore(&state->lock, flags);
+
+	while ((token = strsep(&kbuf, " \t\n")) != NULL) {
+		if (*token == '\0')
+			continue;
+
+		if (!strncmp(token, "mode=", 5)) {
+			ret = sysfs_match_string(page_owner_print_mode_strings,
+						token + 5);
+			if (ret < 0)
+				goto out_free;
+			new_print_mode = ret;
+		} else {
+			ret = -EINVAL;
+			goto out_free;
+		}
+	}
+
+	spin_lock_irqsave(&state->lock, flags);
+	state->print_mode = new_print_mode;
+	spin_unlock_irqrestore(&state->lock, flags);
+
+	ret = count;
+
+out_free:
+	kfree(orig);
+	return ret;
+}
+
 static const struct file_operations page_owner_fops = {
+	.owner		= THIS_MODULE,
+	.open		= page_owner_open,
+	.release	= page_owner_release,
+	.write		= page_owner_write,
 	.read		= read_page_owner,
 	.llseek		= lseek_page_owner,
 };
@@ -1003,7 +1120,7 @@ static int __init pageowner_init(void)
 		return 0;
 	}
 
-	debugfs_create_file("page_owner", 0400, NULL, NULL, &page_owner_fops);
+	debugfs_create_file("page_owner", 0600, NULL, NULL, &page_owner_fops);
 	dir = debugfs_create_dir("page_owner_stacks", NULL);
 	debugfs_create_file("show_stacks", 0400, dir,
 			    (void *)(STACK_PRINT_FLAG_STACK |
_

Patches currently in -mm which might be from zhen.ni@easystack.cn are

mm-page_owner-add-print_mode-filter.patch
mm-page_owner-add-numa-node-filter.patch
tools-mm-add-page_owner_filter-userspace-tool.patch
mm-page_owner-document-page_owner-filter.patch