From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-m17228.xmail.ntesmail.com (mail-m17228.xmail.ntesmail.com [45.195.17.228]) (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 828237404E for ; Tue, 28 Apr 2026 03:36:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.195.17.228 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777347404; cv=none; b=ESwT6ICS0+X0nT11l909rI7tg4AXrO6MQ481lA2t66MPLwKGAoQ/JlL4v5NQWBm98HA4O0FoZZLmjGVUlvNh0meeEQYnD7uSaZudDnD0UNAZ3/nvY7R1D6+tRJwufRl807ztW5ymq8OopYCxGASxvznnN1FT3s778OGpBYp75i8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777347404; c=relaxed/simple; bh=tf4/HFDH85IwqwSv90KE5yxfNzcn7vjW6YlCH4ynoaQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Cw5rpn3HdkUF3w1qCBM5I2+Yl+KABkIeN1TugBjHmnPDwZ723mf9u9N4QXKOi6v3iV0lmhsEHM1Q6jnzUlk6Ka6BIt64euH9SeSPgPHDAR31wERdNWuMVxKXTzVru383kyt8uCOIbQGnmr1Qp+xOY68E24HW4Aaw/u5dTD8wmqE= 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=45.195.17.228 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 [192.168.0.18] (unknown [218.94.118.90]) by smtp.qiye.163.com (Hmail) with ESMTP id 19787b531; Tue, 28 Apr 2026 11:36:30 +0800 (GMT+08:00) Message-ID: <0f9e11c8-743e-45be-8fbc-ea81d7592ae3@easystack.cn> Date: Tue, 28 Apr 2026 11:36:30 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/3] mm/page_owner: add print_mode filter To: Zi Yan Cc: akpm@linux-foundation.org, vbabka@kernel.org, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260419155540.376847-1-zhen.ni@easystack.cn> <20260419155540.376847-3-zhen.ni@easystack.cn> <41EDDEC1-9BAB-447D-AAB0-B8B22289F19C@nvidia.com> From: "zhen.ni" In-Reply-To: <41EDDEC1-9BAB-447D-AAB0-B8B22289F19C@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-HM-Tid: 0a9dd228ecfb0229kunm47e2a607147fff X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFJQjdXWRgWCB1ZQUpXWS1ZQUlXWQ8JGhUIEh9ZQVkaH01OVk9CGEsfGRpKGEoZHlYVFA kWGhdVGRETFhoSFyQUDg9ZV1kYEgtZQVlJSkNVQk9VSkpDVUJLWVdZFhoPEhUdFFlBWU9LSFVKS0 lPT09IVUpLS1VKQktLWQY+ 在 2026/4/27 23:43, Zi Yan 写道: > On 19 Apr 2026, at 11:55, Zhen Ni wrote: > >> 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/ >> Suggested-by: Zi Yan >> Signed-off-by: Zhen Ni >> --- >> >> Changes in v2: >> - Renamed from 'compact mode' to 'print_mode' for better clarity >> - Use enum values (0=full_stack, 1=stack_handle) instead of boolean >> - Update debugfs filename from 'compact' to 'print_mode' >> --- >> mm/page_owner.c | 28 +++++++++++++++++++++++++++- >> 1 file changed, 27 insertions(+), 1 deletion(-) >> >> diff --git a/mm/page_owner.c b/mm/page_owner.c >> index 5884d883837e..6d87b6948cfa 100644 >> --- a/mm/page_owner.c >> +++ b/mm/page_owner.c >> @@ -590,7 +590,13 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn, >> 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 *data, u64 val) >> 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, >> -- >> 2.20.1 > > I think it is more user-friendly to use “full_stack” and “stack_handle” > instead of 0 and 1. You can refer to [1] to sysfs_match_string() to > do that. I was testing the interface, but needed to look at your code > to know which print_mode I am using. ;) > > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/tree/mm/huge_memory.c?h=mm-everything#n380 > > Thanks for the suggestion! I considered using "full_stack" and "stack_handle" strings, but I think the numeric values (0/1) are more concise and easier to type for users. The v3 documentation will clarify the meaning: - 0 (default): Print full stack traces - 1: Print only stack handles Do you think this is sufficient, or would you still prefer using string values instead? > Best Regards, > Yan, Zi > > Best regards, Zhen