Re: [PATCH v2 03/18] mm/ksw: add /proc/kstackwatch interface
From: Mike Rapoport <rppt@kernel.org>
Date: 2025-09-04 07:51:54
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linux-mm, linux-perf-users, lkml
On Thu, Sep 04, 2025 at 08:21:00AM +0800, Jinchao Wang wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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 <linux/kstrtox.h> #include <linux/module.h> +#include <linux/proc_fs.h> +#include <linux/seq_file.h> #include <linux/string.h> +#include <linux/uaccess.h> #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? What happens when there are several "echo .. > /proc/kstackwatch"? And even more interesting what happens if they are parallel?
+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?
+}
...
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
quoted hunk ↗ jump to hunk
+ 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.