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Message-Id: <1618668783-39601-1-git-send-email-zhouchuangao@vivo.com>
Date: Sat, 17 Apr 2021 07:13:01 -0700
From: zhouchuangao <zhouchuangao@...o.com>
To: Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>,
Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
Daniel Bristot de Oliveira <bristot@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Kees Cook <keescook@...omium.org>,
Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
Michal Hocko <mhocko@...e.com>,
"Guilherme G. Piccoli" <gpiccoli@...onical.com>,
Vlastimil Babka <vbabka@...e.cz>,
Lukas Bulwahn <lukas.bulwahn@...il.com>,
zhouchuangao <zhouchuangao@...o.com>,
linux-kernel@...r.kernel.org
Subject: [PATCH] kernel/hung_task: Add a whitelist and blacklist mechanism.
The main purpose of this patch is to add a whitelist and blacklist
mechanism to the hung task thread.
1. Add a /sys/module/hung_task/parameters/hung_seconds interface,
so you can write a specific time to 'hung_seconds' to hang a shell
process for a while. This interface is convenient for us to debug
the function of hung task thread.
eg:
echo 100 > /sys/module/hung_task/parameters/hung_seconds
This will put the current shell process into D state for 100s.
2. Add whitelist and blacklist. If a D state process is on the
whitelist, it will skip checking for that process. In contrast, if
the process is on a blacklist, panic is triggered.
Different use scenarios can make different whitelist and blacklist.
eg:
In Android system, we usually and some processes to the whitelist.
static task_t task_whitelist[] = {
{"mdrt_thread", HUNG_TASK_WHITELIST},
{"chre_kthread", HUNG_TASK_WHITELIST},
{"scp_power_reset", HUNG_TASK_WHITELIST},
{"ccci_fsm1", HUNG_TASK_WHITELIST},
{"qos_ipi_recv", HUNG_TASK_WHITELIST},
{NULL, 0},
};
3. Add a new member hung_state to task_struct to identify the type
of the D state process being detected.
A value of 0x1(HUNG_TASK_WHITELIST) indicates that the process is
on the whitelist.
A value of 0x2(HUNG_TASK_BLACKLIST) indicates that the process is
on the blacklist.
The remaining bits are reserved, and there may be other scenarios
entering the D state that need to be added to hung_state.
Signed-off-by: zhouchuangao <zhouchuangao@...o.com>
---
include/linux/sched.h | 1 +
kernel/hung_task.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 87 insertions(+), 2 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8d5264b..8ffbdf6 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -973,6 +973,7 @@ struct task_struct {
unsigned long last_switch_count;
unsigned long last_switch_time;
unsigned long killed_time;
+ unsigned long hung_state;
#endif
/* Filesystem information: */
struct fs_struct *fs;
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index bb2e3e1..952a44c 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -72,6 +72,57 @@ unsigned int __read_mostly sysctl_hung_task_all_cpu_backtrace;
unsigned int __read_mostly sysctl_hung_task_panic =
CONFIG_BOOTPARAM_HUNG_TASK_PANIC_VALUE;
+#define HUNG_TASK_WHITELIST 0x1
+#define HUNG_TASK_BLACKLIST 0x2
+
+typedef struct {
+ char *task_comm;
+ unsigned long flag;
+} task_t;
+
+static task_t task_whitelist[] = {
+ {NULL, 0},
+};
+
+static task_t task_blacklist[] = {
+ {"init", HUNG_TASK_BLACKLIST},
+ {NULL, 0},
+};
+
+static bool task_in_blacklist(struct task_struct *tsk)
+{
+ task_t *info = NULL;
+
+ if (tsk->hung_state & HUNG_TASK_BLACKLIST)
+ return true;
+
+ for (info = task_blacklist; info->task_comm; info++) {
+ if (!strcmp(tsk->comm, info->task_comm)) {
+ tsk->hung_state |= HUNG_TASK_BLACKLIST;
+ return true;
+ }
+ }
+
+ return false;
+}
+
+static bool task_in_whitelist(struct task_struct *tsk)
+{
+ task_t *info = NULL;
+
+ if (tsk->hung_state & HUNG_TASK_WHITELIST)
+ return true;
+
+ for (info = task_whitelist; info->task_comm; info++) {
+ if (!strcmp(tsk->comm, info->task_comm)) {
+ tsk->hung_state |= HUNG_TASK_WHITELIST;
+ return true;
+ }
+ }
+
+ return false;
+}
+
static int
hung_task_panic(struct notifier_block *this, unsigned long event, void *ptr)
{
@@ -111,6 +162,12 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
if (time_is_after_jiffies(t->last_switch_time + timeout * HZ))
return;
+ /* Check if process 't' is in the whitelist. */
+ if (task_in_whitelist(t)) {
+ pr_info("skip hung task: %s\n", t->comm);
+ return;
+ }
+
trace_sched_process_hang(t);
if (sysctl_hung_task_panic) {
@@ -118,7 +175,6 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
hung_task_show_lock = true;
hung_task_call_panic = true;
}
-
/*
* Ok, the task did not get scheduled for more than 2 minutes,
* complain:
@@ -141,6 +197,12 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
hung_task_show_all_bt = true;
}
+ /* Check if process 't' is in the blacklist. */
+ if (task_in_blacklist(t)) {
+ pr_err("critical task blocked: (%d)%s\n", t->pid, t->comm);
+ hung_task_call_panic = true;
+ }
+
touch_nmi_watchdog();
}
@@ -253,8 +315,10 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
trigger_all_cpu_backtrace();
}
- if (hung_task_call_panic)
+ if (hung_task_call_panic) {
+ show_state_filter(TASK_UNINTERRUPTIBLE);
panic("hung_task: blocked tasks");
+ }
}
static long hung_timeout_jiffies(unsigned long last_checked,
@@ -322,6 +386,7 @@ static int watchdog(void *dummy)
unsigned long hung_last_checked = jiffies;
set_user_nice(current, 0);
+ pr_info("khungtaskd started...\n");
for ( ; ; ) {
unsigned long timeout = sysctl_hung_task_timeout_secs;
@@ -357,3 +422,22 @@ static int __init hung_task_init(void)
return 0;
}
subsys_initcall(hung_task_init);
+
+static int hung_task_test(const char *val, const struct kernel_param *kp)
+{
+ unsigned long sec = 0;
+ if (kstrtoul(val, 10, &sec))
+ return -EINVAL;
+
+ pr_info("Hung task Dsleep %ld s, start!\n", sec);
+ msleep(sec * 1000);
+ pr_info("Hung task Dsleep %ld s, end!\n", sec);
+
+ return 0;
+}
+
+static const struct kernel_param_ops hung_task_test_ops = {
+ .set = hung_task_test,
+};
+
+module_param_cb(hung_seconds, &hung_task_test_ops, NULL, 0600);
--
2.7.4
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