From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 36F5ECA1016 for ; Mon, 8 Sep 2025 06:03:18 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 71DEA8E000D; Mon, 8 Sep 2025 02:03:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6CE518E0001; Mon, 8 Sep 2025 02:03:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5E3F28E000D; Mon, 8 Sep 2025 02:03:17 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 4A5D58E0001 for ; Mon, 8 Sep 2025 02:03:17 -0400 (EDT) Received: from smtpin05.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id F1501BC45C for ; Mon, 8 Sep 2025 06:03:16 +0000 (UTC) X-FDA: 83865040392.05.9ACB399 Received: from mail-pg1-f174.google.com (mail-pg1-f174.google.com [209.85.215.174]) by imf04.hostedemail.com (Postfix) with ESMTP id 18E7740003 for ; Mon, 8 Sep 2025 06:03:14 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=IN79HQh0; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf04.hostedemail.com: domain of wangjinchao600@gmail.com designates 209.85.215.174 as permitted sender) smtp.mailfrom=wangjinchao600@gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1757311395; a=rsa-sha256; cv=none; b=hXA4/v+eNk43xRa2fdBf/Nh2REFKhsYa4ZMfldm+potexwg7v0D4LDg3ReTQn61Lc+y6YQ qbKf7t51CYhScijHhvm5gvTWhHC6xkb15EmrHw5xTBlV3nyi7kucDJixOkdXRW0m+YCsHZ Uxpbu4kQQvzGicYXMEACxjyDfpYS59Y= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=IN79HQh0; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf04.hostedemail.com: domain of wangjinchao600@gmail.com designates 209.85.215.174 as permitted sender) smtp.mailfrom=wangjinchao600@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1757311395; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ZNWdSFuO4znuntXPxqyseJzzxpqp1vGgxisD3Po8ZRc=; b=5cva1Xm6AKovEOX4WPPgeLHfbDHdUyb/2C+MLjHehJyVghn6dSol5MXiSQ5TBFM2q3qj9f QNseTVA2v0RptKHjOZuULJlxinZXAmReDVSCfn1ZHQde+hUcCCG99x3ETNqgiT1JwOZVKf DsqaM1Z8xAkDEvxDKH5wIhZqRhJSu4A= Received: by mail-pg1-f174.google.com with SMTP id 41be03b00d2f7-b482fd89b0eso3523075a12.2 for ; Sun, 07 Sep 2025 23:03:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1757311394; x=1757916194; darn=kvack.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=ZNWdSFuO4znuntXPxqyseJzzxpqp1vGgxisD3Po8ZRc=; b=IN79HQh03XhF0fCxJbIOnhCllAJskAtyigFnhokbU06Rb7gzAxiDqaibKkswHBL1iV wb4LzJyGi2+NrtSY0QkP98peCBj6xCIkvZwUzOlymQBWzrL0E806YgFScdaSUrcNpPsK U+Onl+8d4raCCOUHJjDSM1a/+2c4fv09uTyqjgIugQNm3//r0XLdJrfLmplt3cGRvw19 IHeeVD2kAyy5qgr5PQKUzhP8d+N3+Se4/PabzO4SHjJy0piTsShci2gCNn9bN1AGvHgT FteDR9e+QzZ9fWKB6sMVtJF36nYGvDvGuOTpBfmsodxQVUUWaLkdBFl0PMrVoYP9qcPk 1zbg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1757311394; x=1757916194; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=ZNWdSFuO4znuntXPxqyseJzzxpqp1vGgxisD3Po8ZRc=; b=Kws4VI2SEjiE8i1HMDWHU8JgAfslNAxdgMKkDk1ZjnIE2S870V7vmMzf1j4drH3uNg 1GcKi6uRQ42gJvF+qrbuECrZC5WNYPQ1/f/w2hau674ZBSsnz549oBHUpCWIT/+rEkA5 HQFVQAdGvR2hYFUYvVm47uranDGtWuvhVpVB6DOHSZLNomb9LpFaqQn+wP6/AgSta11i C1NaPrympHkxhdSkDXV+rLrrOa4uHnPzluqBciPvv5abRDXV5niF5MzA5o31wP7spw6X UJbGaiIhWYnoPsS4BiyOx5EYY5uHq5PhAVIlz2FVN5K4vSyJ2Rojmntp9kqflrJEfoUB t6mw== X-Forwarded-Encrypted: i=1; AJvYcCXPYhPTz9zHLAfZFszXNCNHsDkU1SiOBVEoPtrWyzKIogGW9aIdtewaRzga3NxLOxu+OQDdH42y9Q==@kvack.org X-Gm-Message-State: AOJu0YxdnhLoEWwrwzD4HDCl0XI0X1A/XF8HddW4pfSQiYjM4SYWewz5 ZCKSOYlo0Yot/OwqVYxBi5jE1KRean2VPWVK9jC72mEP9QRSxDjAkLUo X-Gm-Gg: ASbGncvYYjjfC9EWQUPwiQ3lGwy13xmMh5tJQqHDQ6Ki6J52cLRHRIZ0sKHAACBpaE+ zzBJ5uXJZLRzXUtaNY3GyVpcKFTQ16RY7TyasMY4DMaE30RPBsyoR2BHtbUqt/BDfO2/sG8eNpN gyb5Pm0AnYKedEycvm9Z3GmRH3bRqJZ6SMA4tDzJeoyPlN2Bhb89anJkZCOBO1cUpsVk/wj7zEc 6AK81j1YsAbpacZi0lYonW1kZB3XXgE7wvGoRIUBHG/pg5bGGQyKxGIDHyVnjJMJtpWYbrjfosD xj1nabE3bS+24IoyQIZe0tVAPg0j16vqJMqQ6p+/y9y2BeSYpiHpvLnyARjD1X/FUIhGFhBAWbs qukQ0QpgXsWQTOsm+9/mPXemn3HWxzo5QegDo2Q== X-Google-Smtp-Source: AGHT+IGaMF5Ba8B6t4H2vzMTPALt55ZTJj/NUECpMhpJBlfxz2OnagbMjg7YIyiTxu2dTK5kF1UxJg== X-Received: by 2002:a17:902:e541:b0:24c:9c29:c9d1 with SMTP id d9443c01a7336-2517493a09dmr107170825ad.59.1757311393773; Sun, 07 Sep 2025 23:03:13 -0700 (PDT) Received: from localhost ([103.121.208.62]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-24b11833ac7sm166868285ad.55.2025.09.07.23.03.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 07 Sep 2025 23:03:13 -0700 (PDT) Date: Mon, 8 Sep 2025 14:03:11 +0800 From: Jinchao Wang To: Mike Rapoport Cc: Andrew Morton , Masami Hiramatsu , "Naveen N . Rao" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Peter Zijlstra , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , "Liang, Kan" , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , linux-perf-users@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 03/18] mm/ksw: add /proc/kstackwatch interface Message-ID: References: <20250904002126.1514566-1-wangjinchao600@gmail.com> <20250904002126.1514566-4-wangjinchao600@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: 18E7740003 X-Stat-Signature: b9eay9s34ku5ydkwfmbd4y5mgpg6e76s X-HE-Tag: 1757311394-744222 X-HE-Meta: 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 B6+xLSQH 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Sep 04, 2025 at 10:51:41AM +0300, Mike Rapoport wrote: > On Thu, Sep 04, 2025 at 08:21:00AM +0800, Jinchao Wang wrote: > > Provide the /proc/kstackwatch file to read or update the KSW configuration. > > Writing a valid config string starts watching; empty input stops watching. > > Invalid input stops watching and reports an error. > > > > Allocate a ksw_config struct on module init and free it on exit. > > Manage watching state with ksw_start_watching() and ksw_stop_watching(). > > > > Signed-off-by: Jinchao Wang > > --- > > mm/kstackwatch/kernel.c | 140 ++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 140 insertions(+) > > > > diff --git a/mm/kstackwatch/kernel.c b/mm/kstackwatch/kernel.c > > index 4a6dc49449fe..95ade95abde1 100644 > > --- a/mm/kstackwatch/kernel.c > > +++ b/mm/kstackwatch/kernel.c > > @@ -1,7 +1,10 @@ > > // SPDX-License-Identifier: GPL-2.0 > > #include > > #include > > +#include > > +#include > > #include > > +#include > > > > #include "kstackwatch.h" > > > > @@ -9,6 +12,29 @@ MODULE_AUTHOR("Jinchao Wang"); > > MODULE_DESCRIPTION("Kernel Stack Watch"); > > MODULE_LICENSE("GPL"); > > > > +struct ksw_config *ksw_config; > > Does a global ksw_config imply that this is a singleton? Yes, it is. > What happens when there are several "echo .. > /proc/kstackwatch"? > And even more interesting what happens if they are parallel? I did not consider this deeply enough. I will address it properly in the next series. Thank you for pointing it out. > > > +bool watching_active; > > + > > +bool panic_on_catch; > > +module_param(panic_on_catch, bool, 0644); > > +MODULE_PARM_DESC(panic_on_catch, > > + "Trigger a kernel panic immediately on corruption catch"); > > + > > +static int ksw_start_watching(void) > > +{ > > + watching_active = true; > > + > > + pr_info("KSW: start watching %s\n", ksw_config->config_str); > > + return 0; > > +} > > + > > +static void ksw_stop_watching(void) > > +{ > > + watching_active = false; > > + > > + pr_info("KSW: stop watching %s\n", ksw_config->config_str); > > This module is overly verbose. Do you really need all the printks? You’re right — many of these printks are for early debugging and not needed for production. I will remove or downgrade them to pr_debug() in the next version. For critical paths, I’ll ensure only actionable or WARN-level messages remain. Appreciate the push for cleaner logging. > > > +} > > ... > > > static int __init kstackwatch_init(void) > > { > > + ksw_config = kmalloc(sizeof(*ksw_config), GFP_KERNEL); > > + if (!ksw_config) > > + return -ENOMEM; > > + > > + /* Create proc interface */ > > + if (!proc_create("kstackwatch", 0644, NULL, &kstackwatch_proc_ops)) { > > ksw_config must be freed here > > > + pr_err("KSW: create proc kstackwatch fail"); > > + return -ENOMEM; > > + } > > + > > pr_info("KSW: module loaded\n"); > > pr_info("KSW: usage:\n"); > > pr_info("KSW: echo 'function+ip_offset[+depth] [local_var_offset:local_var_len]' > /proc/kstackwatch\n"); > > @@ -85,6 +217,14 @@ static int __init kstackwatch_init(void) > > > > static void __exit kstackwatch_exit(void) > > { > > + /* Cleanup active watching */ > > + if (watching_active) > > + ksw_stop_watching(); > > + > > + /* Remove proc interface */ > > + remove_proc_entry("kstackwatch", NULL); > > + kfree(ksw_config); > > + > > pr_info("KSW: Module unloaded\n"); > > } > > > > -- > > 2.43.0 > > > > -- > Sincerely yours, > Mike.