From nobody Sat Jun 13 03:28:28 2026 Received: from mail-m49201.qiye.163.com (mail-m49201.qiye.163.com [45.254.49.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 615991E32A2 for ; Mon, 11 May 2026 03:35:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.254.49.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778470548; cv=none; b=o0+NyS3QkqHN/d5+uvUVHLp/myGPcSDxIHU4lJGKrtjojX9Bxk6a0zLoW7qzWQy2rld9Mvc6kyF1LD+j7hA7q8c/hRN7as+dtLXfUvBiLFfOx88EIvs0xcv/jORVdfGggRNueCzUMaOfZ7U/3A+E4mRLQh9ustXpmQMWmQDDW5U= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778470548; c=relaxed/simple; bh=Jas+DeytpcEmtDfD/khf+RNvEUh4R0pURJuakb57Ol0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=igo84HJp+HvEV7gerT9lDE053PrkeE7fAFoZ+AFSFpgOiFcsriB/JFxE9cS0DF7AjshtRgPfukN/ku8vEcIWhmJBDzZrmyZAT3RJ7Wgda628Dv6DebrMgrEtfnBvnGuYAL76YNDcdqF4IVJ6tnz7HbyFTrgdwf26SyQ36BfZnA0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=easystack.cn; spf=pass smtp.mailfrom=easystack.cn; arc=none smtp.client-ip=45.254.49.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=easystack.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=easystack.cn Received: from localhost.localdomain (unknown [218.94.118.90]) by smtp.qiye.163.com (Hmail) with ESMTP id 19f361871; Mon, 11 May 2026 11:30:27 +0800 (GMT+08:00) From: Zhen Ni To: akpm@linux-foundation.org, vbabka@kernel.org Cc: surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Zhen Ni , SeongJae Park Subject: [PATCH v6 1/3] mm/page_owner: add print_mode filter Date: Mon, 11 May 2026 11:30:15 +0800 Message-Id: <20260511033017.747781-2-zhen.ni@easystack.cn> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20260511033017.747781-1-zhen.ni@easystack.cn> References: <20260511033017.747781-1-zhen.ni@easystack.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-HM-Tid: 0a9e15160fb70229kunm0464dab52dcf00 X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFJQjdXWRgWCB1ZQUpXWS1ZQUlXWQ8JGhUIEh9ZQVkaT0hNVhgdGB0aGkwdH09JH1YVFA kWGhdVGRETFhoSFyQUDg9ZV1kYEgtZQVlJSkNVQk9VSkpDVUJLWVdZFhoPEhUdFFlBWU9LSFVKS0 lPT09IVUpLS1VKQktLWQY+ Content-Type: text/plain; charset="utf-8" Add a print_mode filter to page_owner that allows users to choose between printing full stack traces or only stack handles, significantly reducing output size for debugging and analysis. The filter provides a string-based interface under /sys/kernel/debug/page_owner_filter/: - Reading shows the current mode with [] brackets around active option - Writing accepts "full_stack" or "stack_handle" strings The default full_stack mode maintains backward compatibility with existing usage, displaying complete stack traces for each page allocation. The stack_handle mode dramatically reduces log size by showing only the handle number instead of the full stack trace. The mapping from handles to actual stack traces can be obtained via the show_stacks_handles interface. Example usage: # echo stack_handle > /sys/kernel/debug/page_owner_filter/print_mode # cat /sys/kernel/debug/page_owner_filter/print_mode full_stack [stack_handle] # cat /sys/kernel/debug/page_owner 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=3D0|zone=3D1) handle: 17432583 ... Reviewed-by: SeongJae Park Signed-off-by: Zhen Ni Reviewed-by: Oscar Salvador --- Changes in v6: - Remove unnecessary braces in if/else statement (coding style) - Use stack array (char kbuf[33]) instead of kmalloc for input buffer Changes in v5: - No code changes Changes in v4: - Change from numeric (0/1) to string-based interface ("full_stack"/"stack_= handle") - Merge infrastructure patch into this patch Changes in v3: - No code changes Changes in v2: - Renamed from 'compact mode' to 'print_mode' for better clarity - Use enum values (0=3Dfull_stack, 1=3Dstack_handle) instead of boolean - Update debugfs filename from 'compact' to 'print_mode' v5: https://lore.kernel.org/linux-mm/20260507064643.179187-2-zhen.ni@easyst= ack.cn/ v4: https://lore.kernel.org/linux-mm/20260430163247.13628-2-zhen.ni@easysta= ck.cn/ v3: https://lore.kernel.org/linux-mm/20260428071112.1420380-2-zhen.ni@easys= tack.cn/ https://lore.kernel.org/linux-mm/20260428071112.1420380-3-zhen.ni@easys= tack.cn/ v2: https://lore.kernel.org/linux-mm/20260419155540.376847-2-zhen.ni@easyst= ack.cn/ https://lore.kernel.org/linux-mm/20260419155540.376847-3-zhen.ni@easyst= ack.cn/ v1: https://lore.kernel.org/linux-mm/20260417154638.22370-2-zhen.ni@easysta= ck.cn/ https://lore.kernel.org/linux-mm/20260417154638.22370-3-zhen.ni@easysta= ck.cn/ --- mm/page_owner.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 80 insertions(+), 2 deletions(-) diff --git a/mm/page_owner.c b/mm/page_owner.c index 8178e0be557f..27a412c52d41 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 #include +#include #include #include #include @@ -54,6 +55,24 @@ struct stack_print_ctx { u8 flags; }; =20 +enum page_owner_print_mode { + PAGE_OWNER_PRINT_FULL_STACK, + PAGE_OWNER_PRINT_STACK_HANDLE, +}; + +static const char * const page_owner_print_mode_strings[] =3D { + [PAGE_OWNER_PRINT_FULL_STACK] =3D "full_stack", + [PAGE_OWNER_PRINT_STACK_HANDLE] =3D "stack_handle", +}; + +struct page_owner_filter { + enum page_owner_print_mode print_mode; +}; + +static struct page_owner_filter owner_filter =3D { + .print_mode =3D PAGE_OWNER_PRINT_FULL_STACK, +}; + static bool page_owner_enabled __initdata; DEFINE_STATIC_KEY_FALSE(page_owner_inited); =20 @@ -575,7 +594,11 @@ print_page_owner(char __user *buf, size_t count, unsig= ned long pfn, migratetype_names[pageblock_mt], &page->flags); =20 - ret +=3D stack_depot_snprint(handle, kbuf + ret, count - ret, 0); + if (READ_ONCE(owner_filter.print_mode) =3D=3D PAGE_OWNER_PRINT_STACK_HAND= LE) + ret +=3D scnprintf(kbuf + ret, count - ret, + "handle: %d\n", handle); + else + ret +=3D stack_depot_snprint(handle, kbuf + ret, count - ret, 0); if (ret >=3D count) goto err; =20 @@ -970,10 +993,60 @@ static int page_owner_threshold_set(void *data, u64 v= al) DEFINE_SIMPLE_ATTRIBUTE(page_owner_threshold_fops, &page_owner_threshold_g= et, &page_owner_threshold_set, "%llu"); =20 +static ssize_t print_mode_read(struct file *file, char __user *buf, + size_t count, loff_t *ppos) +{ + const char *output; + int mode; + + mode =3D READ_ONCE(owner_filter.print_mode); + + if (mode =3D=3D PAGE_OWNER_PRINT_FULL_STACK) + output =3D "[full_stack] stack_handle\n"; + else + output =3D "full_stack [stack_handle]\n"; + + return simple_read_from_buffer(buf, count, ppos, output, strlen(output)); +} + +static ssize_t print_mode_write(struct file *file, + const char __user *buf, + size_t count, loff_t *ppos) +{ + char kbuf[32 + 1]; + int mode; + + /* + * Limit input size. Maximum valid input is "stack_handle" (12 chars) + * plus newline and null terminator. Use 32 bytes as a reasonable limit. + */ + if (count > 32) + return -EINVAL; + + if (strncpy_from_user(kbuf, buf, count) < 0) + return -EFAULT; + kbuf[count] =3D '\0'; + + mode =3D sysfs_match_string(page_owner_print_mode_strings, kbuf); + if (mode < 0) + return -EINVAL; + + WRITE_ONCE(owner_filter.print_mode, mode); + + return count; +} + +static const struct file_operations page_owner_print_mode_fops =3D { + .owner =3D THIS_MODULE, + .read =3D print_mode_read, + .write =3D print_mode_write, + .llseek =3D default_llseek, +}; + =20 static int __init pageowner_init(void) { - struct dentry *dir; + struct dentry *dir, *filter_dir; =20 if (!static_branch_unlikely(&page_owner_inited)) { pr_info("page_owner is disabled\n"); @@ -981,6 +1054,11 @@ static int __init pageowner_init(void) } =20 debugfs_create_file("page_owner", 0400, NULL, NULL, &page_owner_fops); + + filter_dir =3D debugfs_create_dir("page_owner_filter", NULL); + debugfs_create_file("print_mode", 0600, filter_dir, NULL, + &page_owner_print_mode_fops); + dir =3D debugfs_create_dir("page_owner_stacks", NULL); debugfs_create_file("show_stacks", 0400, dir, (void *)(STACK_PRINT_FLAG_STACK | --=20 2.20.1 From nobody Sat Jun 13 03:28:28 2026 Received: from mail-m1973181.qiye.163.com (mail-m1973181.qiye.163.com [220.197.31.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4813C21CC51 for ; Mon, 11 May 2026 03:45:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.81 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778471158; cv=none; b=uEVjqP6xWWRQ3i5f6MwiQx5llZX8wXlwSeWiQplGFnqCRfsWnMgYOp13Xphj3hvG8FZTAc9v6VyoHy3qTm12nAoE/MiU39s7syZiko1Idz14iIdO4eftDGNHzCREXEV1vEVjt6r8hHMdlUmfqYZwClErn+sCrbMfeceey4KUFF8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778471158; c=relaxed/simple; bh=M9A/IRsc7Glqk+nYOtVyC2vpXobY9x7PEU32XyxwDnw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=D6ChyYglbEyfECsUXn7dHBVRRUS0VIFJebxmBZED/Z04ID+HRcRxekTAGwQN8KK3dYFNci+i3pjDtBhIYmRzSY1RGInYE5EFu7a8GF+oLQWCsi5qQORLfWoVyO4pObfjw11f5ACRUplfNbG5XzT33zE+S7SoDov0n8oyVzfp8KM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=easystack.cn; spf=pass smtp.mailfrom=easystack.cn; arc=none smtp.client-ip=220.197.31.81 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=easystack.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=easystack.cn Received: from localhost.localdomain (unknown [218.94.118.90]) by smtp.qiye.163.com (Hmail) with ESMTP id 19f361878; Mon, 11 May 2026 11:30:29 +0800 (GMT+08:00) From: Zhen Ni To: akpm@linux-foundation.org, vbabka@kernel.org Cc: surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Zhen Ni Subject: [PATCH v6 2/3] mm/page_owner: add NUMA node filter with nodelist support Date: Mon, 11 May 2026 11:30:16 +0800 Message-Id: <20260511033017.747781-3-zhen.ni@easystack.cn> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20260511033017.747781-1-zhen.ni@easystack.cn> References: <20260511033017.747781-1-zhen.ni@easystack.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-HM-Tid: 0a9e1516158f0229kunm0464dab52dcf0b X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFJQjdXWRgWCB1ZQUpXWS1ZQUlXWQ8JGhUIEh9ZQVlCGh1OVk8fGEJCSklKTh1KSFYVFA kWGhdVGRETFhoSFyQUDg9ZV1kYEgtZQVlJSkNVQk9VSkpDVUJLWVdZFhoPEhUdFFlBWU9LSFVKS0 lPT09IVUpLS1VKQktLWQY+ Content-Type: text/plain; charset="utf-8" Add NUMA node filtering functionality to page_owner to allow filtering pages by specific NUMA node(s). This is useful for NUMA-aware memory allocation analysis and debugging. The filter supports flexible nodelist input formats: - Single node: echo "0" > nid - Multiple nodes: echo "0,2,3" > nid - Node range: echo "0-3" > nid - Mixed format: echo "0,2-4,7" > nid - Clear filter: echo > nid (empty string) The implementation uses nodemask_t for efficient multi-node filtering and nodelist_parse() for flexible input parsing. Empty input clears the filter. Note: Access to nid_mask uses plain load/store without locking because nodemask_t is too large (128 bytes) for READ_ONCE/WRITE_ONCE. This is safe for debug use: low-frequency changes and torn reads would only cause temporary inconsistency in debug output. Signed-off-by: Zhen Ni --- Changes in v6: - Add node validity check using nodes_subset to reject invalid node numbers that don't exist in the system - Move bool filter_by_nid declaration to top of block - Use kmalloc_objs instead of kmalloc - Remove 100 bytes overhead Changes in v5: - Optimize nodes_empty() check in page iteration loop - Add __data_racy qualifier to nid_mask field Changes in v4: - Remove "-1" support, use empty string to clear filter - Use strncpy_from_user() instead of copy_from_user() - Add concurrency safety documentation for nid_mask access - Rename fops to page_owner_nid_filter_fops for consistency Changes in v3: - Remove READ_ONCE/WRITE_ONCE for nodemask_t (fixes compilation errors) * nodemask_t is a large structure (128 bytes) that triggers compile-time = asserts * Direct assignment is safe for this use case - Add comment explaining input length calculation formula * 6 bytes =3D ",NNNNN" (comma + 5-digit node number) - Simplify "-1" check using kstrtoint() instead of dual strcmp() - Move nodemask_t mask read outside PFN iteration loop for performance * Avoids 128-byte structure copy on each iteration Changes in v2: - Use nodemask_t instead of int to support multiple nodes - Implement nodelist_parse() to support flexible input formats * Single node: "0", "2" * Multiple nodes: "0,2,3" * Ranges: "0-3" * Mixed: "0,2-4,7" - Use %*pbl format for output (e.g., "0-2", "0,2-4,7") - Use dynamic memory allocation (kmalloc) to handle variable-length input - Follow cpuset's max_write_len pattern: (100 + 6 * MAX_NUMNODES) v5: https://lore.kernel.org/linux-mm/20260507064643.179187-3-zhen.ni@easyst= ack.cn/ v4: https://lore.kernel.org/linux-mm/20260430163247.13628-3-zhen.ni@easysta= ck.cn/ v3: https://lore.kernel.org/linux-mm/20260428071112.1420380-4-zhen.ni@easys= tack.cn/ v2: https://lore.kernel.org/linux-mm/20260419155540.376847-4-zhen.ni@easyst= ack.cn/ v1: https://lore.kernel.org/linux-mm/20260417154638.22370-4-zhen.ni@easysta= ck.cn/ --- mm/page_owner.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) diff --git a/mm/page_owner.c b/mm/page_owner.c index 27a412c52d41..8a38005539ff 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -67,10 +67,16 @@ static const char * const page_owner_print_mode_strings= [] =3D { =20 struct page_owner_filter { enum page_owner_print_mode print_mode; + /* + * Lockless access: nodemask_t exceeds READ_ONCE/WRITE_ONCE size limit. + * Torn reads acceptable for debug interface with infrequent writes. + */ + nodemask_t __data_racy nid_mask; }; =20 static struct page_owner_filter owner_filter =3D { .print_mode =3D PAGE_OWNER_PRINT_FULL_STACK, + .nid_mask =3D NODE_MASK_NONE, }; =20 static bool page_owner_enabled __initdata; @@ -687,6 +693,8 @@ read_page_owner(struct file *file, char __user *buf, si= ze_t count, loff_t *ppos) struct page_ext *page_ext; struct page_owner *page_owner; depot_stack_handle_t handle; + nodemask_t mask; + bool filter_by_nid; =20 if (!static_branch_unlikely(&page_owner_inited)) return -EINVAL; @@ -700,6 +708,9 @@ read_page_owner(struct file *file, char __user *buf, si= ze_t count, loff_t *ppos) while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) !=3D 0) pfn++; =20 + mask =3D owner_filter.nid_mask; + filter_by_nid =3D !nodes_empty(mask); + /* Find an allocated page */ for (; pfn < max_pfn; pfn++) { /* @@ -732,6 +743,14 @@ read_page_owner(struct file *file, char __user *buf, s= ize_t count, loff_t *ppos) if (unlikely(!page_ext)) continue; =20 + /* NUMA node filter using bitmask */ + if (filter_by_nid) { + int nid =3D page_to_nid(page); + + if (!node_isset(nid, mask)) + goto ext_put_continue; + } + /* * Some pages could be missed by concurrent allocation or free, * because we don't hold the zone lock. @@ -1043,6 +1062,77 @@ static const struct file_operations page_owner_print= _mode_fops =3D { .llseek =3D default_llseek, }; =20 +static ssize_t nid_filter_write(struct file *file, + const char __user *buf, + size_t count, loff_t *ppos) +{ + char *kbuf; + nodemask_t mask; + int ret; + + /* + * Limit input size to handle worst-case nodelist (all nodes). + * Worst case per node: ",NNNNN" (comma + 5-digit node number) =3D 6 byte= s. + */ + if (count > (6 * MAX_NUMNODES)) + return -EINVAL; + + kbuf =3D kmalloc_objs(*kbuf, count + 1); + if (!kbuf) + return -ENOMEM; + + if (strncpy_from_user(kbuf, buf, count) < 0) { + ret =3D -EFAULT; + goto out_free; + } + kbuf[count] =3D '\0'; + + /* Support nodelist format like "0", "0,2", "0-3", or empty to clear */ + if (nodelist_parse(kbuf, mask)) { + ret =3D -EINVAL; + goto out_free; + } + + /* Validate that all specified nodes actually exist in the system */ + if (!nodes_subset(mask, node_states[N_MEMORY])) { + ret =3D -EINVAL; + goto out_free; + } + + owner_filter.nid_mask =3D mask; + ret =3D count; + +out_free: + kfree(kbuf); + return ret; +} + +static int nid_filter_show(struct seq_file *m, void *v) +{ + nodemask_t mask =3D owner_filter.nid_mask; + + if (nodes_empty(mask)) + seq_puts(m, "\n"); + else + seq_printf(m, "%*pbl\n", nodemask_pr_args(&mask)); + + return 0; +} + +static int nid_filter_open(struct inode *inode, struct file *file) +{ + return single_open(file, nid_filter_show, NULL); +} + +static const struct file_operations page_owner_nid_filter_fops =3D { + .owner =3D THIS_MODULE, + .open =3D nid_filter_open, + .read =3D seq_read, + .llseek =3D seq_lseek, + .write =3D nid_filter_write, + .release =3D single_release, +}; + =20 static int __init pageowner_init(void) { @@ -1058,6 +1148,8 @@ static int __init pageowner_init(void) filter_dir =3D debugfs_create_dir("page_owner_filter", NULL); debugfs_create_file("print_mode", 0600, filter_dir, NULL, &page_owner_print_mode_fops); + debugfs_create_file("nid", 0600, filter_dir, NULL, + &page_owner_nid_filter_fops); =20 dir =3D debugfs_create_dir("page_owner_stacks", NULL); debugfs_create_file("show_stacks", 0400, dir, --=20 2.20.1 From nobody Sat Jun 13 03:28:28 2026 Received: from mail-m3281.qiye.163.com (mail-m3281.qiye.163.com [220.197.32.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ADF7F22A7F0 for ; Mon, 11 May 2026 03:46:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.32.81 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778471165; cv=none; b=hky2YT0CdiPQ0Ihv28adOMqGNkEziJ9/0ej9DexX7u1iHoEK+fOV5roXb8o9iFcr8TrXGaVoUBK2xo9L5rLF0n4U1h7dqJMbkCTOPi+NeJ5W6F7R3HfkYFpvbr4lFfc4h0mDhn35mj8j7+Tp8kVd69eli3XTeDH/6jfKvzfijf4= ARC-Message-Signature: i=1; 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charset="utf-8" Add documentation for the page_owner filter functionality, including: - Print mode filter (full stack vs stack handle) - NUMA node filter (single node, multiple nodes, ranges) - Usage examples for both filters Reviewed-by: SeongJae Park Signed-off-by: Zhen Ni Reviewed-by: Oscar Salvador --- Changes in v6: - No code changes Changes in v5: - No code changes Changes in v4: - Update print_mode documentation to reflect string-based interface * Change from "0/1" to "full_stack"/"stack_handle" * Add bracket notation example: "[full_stack] stack_handle" - Update NUMA filter documentation * Remove "-1" example * Add empty string as clear method - Fix indentation: use tabs instead of spaces in code examples Changes in v3: - New patch to document filter features as requested by Andrew Morton v5: https://lore.kernel.org/linux-mm/20260507064643.179187-4-zhen.ni@easyst= ack.cn/ v4: https://lore.kernel.org/linux-mm/20260430163247.13628-4-zhen.ni@easysta= ck.cn/ v3: https://lore.kernel.org/linux-mm/20260428071112.1420380-5-zhen.ni@easys= tack.cn/ --- Documentation/mm/page_owner.rst | 61 ++++++++++++++++++++++++++++++++- 1 file changed, 60 insertions(+), 1 deletion(-) diff --git a/Documentation/mm/page_owner.rst b/Documentation/mm/page_owner.= rst index 6b12f3b007ec..178bacfbb3fd 100644 --- a/Documentation/mm/page_owner.rst +++ b/Documentation/mm/page_owner.rst @@ -74,7 +74,17 @@ Usage =20 3) Do the job that you want to debug. =20 -4) Analyze information from page owner:: +4) (Optional) Use filters to focus on specific memory allocations:: + + cd /sys/kernel/debug/page_owner_filter + + # Print only stack handles instead of full traces + echo stack_handle > print_mode + + # Filter by NUMA nodes + echo "0,2-3" > nid + +5) Analyze information from page owner:: =20 cat /sys/kernel/debug/page_owner_stacks/show_stacks > stacks.txt cat stacks.txt @@ -238,6 +248,55 @@ Usage ./page_owner_sort --tgid=3D1,2,3 ./page_owner_sort --name name1,name2 =20 +Page Owner Filters +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +The page_owner feature provides filtering capabilities to focus on specific +memory allocations (e.g., by NUMA node). Filters are controlled through de= bugfs +files in ``/sys/kernel/debug/page_owner_filter/``. + +Print Mode Filter +----------------- + +The ``print_mode`` file controls the level of detail in stack trace output. + +Available modes: + +- ``full_stack`` (default): Print full stack traces +- ``stack_handle``: Print only stack handles + +Reading the file shows the current mode with brackets around the active op= tion:: + + cat /sys/kernel/debug/page_owner_filter/print_mode + [full_stack] stack_handle + +The ``stack_handle`` mode significantly reduces output size. Instead of fu= ll +stack traces, it prints only the handle number:: + + 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(...) + handle: 17432583 + +To retrieve the full stack trace for a handle, use:: + + cat /sys/kernel/debug/page_owner_stacks/show_stacks_handles + +NUMA Node Filter +---------------- + +The ``nid`` file filters pages by NUMA node. This is useful for NUMA-aware +environments to analyze node-specific memory allocation. + +Supported input formats: + +- Single node: ``echo "2" > nid`` +- Multiple nodes: ``echo "0,2,3" > nid`` +- Node range: ``echo "0-3" > nid`` +- Mixed format: ``echo "0,2-4,7" > nid`` +- Clear filter: ``echo > nid`` (empty string) + STANDARD FORMAT SPECIFIERS =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D :: --=20 2.20.1