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Each detailed report decrements the sysctl, so once it reaches zero, the configured limit is lost and cannot be restored automatically. Keep sysctl_hung_task_warnings unchanged and track the remaining budget in hung_task_warnings_printed. Reset the runtime budget when a watchdog check sees no hung tasks or when userspace writes a new sysctl value. Assisted-by: Antigravity:gemini-3.5-flash Suggested-by: Petr Mladek Reviewed-by: Lance Yang Tested-by: Lance Yang Signed-off-by: Aaron Tomlin --- Documentation/admin-guide/sysctl/kernel.rst | 5 +-- kernel/hung_task.c | 34 ++++++++++++++++----- 2 files changed, 30 insertions(+), 9 deletions(-) diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index c6994e55d141..b0f8e55efc1a 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -459,8 +459,9 @@ hung_task_warnings ================== The maximum number of warnings to report. During a check interval -if a hung task is detected, this value is decreased by 1. -When this value reaches 0, no more warnings will be reported. +if a hung task is detected, the internal warning budget is decreased by 1. +When this budget reaches 0, no more detailed warnings will be reported. The +warning budget is reset to the configured limit when no hung task is found. This file shows up if ``CONFIG_DETECT_HUNG_TASK`` is enabled. -1: report an infinite number of warnings. diff --git a/kernel/hung_task.c b/kernel/hung_task.c index 6fcc94ce4ca9..4e1fb0db79d1 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -59,6 +59,8 @@ static unsigned long __read_mostly sysctl_hung_task_check_interval_secs; static int __read_mostly sysctl_hung_task_warnings = 10; +static int hung_task_warnings_printed = 10; + static int __read_mostly did_panic; static bool hung_task_call_panic; @@ -247,9 +249,9 @@ static void hung_task_info(struct task_struct *t, unsigned long timeout, * CONFIG_DEFAULT_HUNG_TASK_TIMEOUT. Therefore, complain * accordingly */ - if (sysctl_hung_task_warnings || hung_task_call_panic) { - if (sysctl_hung_task_warnings > 0) - sysctl_hung_task_warnings--; + if (hung_task_warnings_printed || hung_task_call_panic) { + if (hung_task_warnings_printed > 0) + hung_task_warnings_printed--; pr_err("INFO: task %s:%d blocked%s for more than %ld seconds.\n", t->comm, t->pid, t->in_iowait ? " in I/O wait" : "", (jiffies - t->last_switch_time) / HZ); @@ -264,7 +266,7 @@ static void hung_task_info(struct task_struct *t, unsigned long timeout, sched_show_task(t); debug_show_blocker(t, timeout); - if (!sysctl_hung_task_warnings) + if (!hung_task_warnings_printed) pr_info("Future hung task reports are suppressed, see sysctl kernel.hung_task_warnings\n"); } @@ -304,7 +306,7 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) unsigned long last_break = jiffies; struct task_struct *g, *t; unsigned long this_round_count; - int need_warning = sysctl_hung_task_warnings; + int need_warning = hung_task_warnings_printed; unsigned long si_mask = hung_task_si_mask; /* @@ -340,8 +342,10 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) unlock: rcu_read_unlock(); - if (!this_round_count) + if (!this_round_count) { + hung_task_warnings_printed = sysctl_hung_task_warnings; return; + } if (need_warning || hung_task_call_panic) { si_mask |= SYS_INFO_LOCKS; @@ -425,6 +429,22 @@ static int proc_dohung_task_timeout_secs(const struct ctl_table *table, int writ return ret; } +static int proc_dohung_task_warnings(const struct ctl_table *table, int write, + void *buffer, + size_t *lenp, loff_t *ppos) +{ + int ret; + + ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); + + if (ret || !write) + return ret; + + hung_task_warnings_printed = sysctl_hung_task_warnings; + + return 0; +} + /* * This is needed for proc_doulongvec_minmax of sysctl_hung_task_timeout_secs * and hung_task_check_interval_secs @@ -480,7 +500,7 @@ static const struct ctl_table hung_task_sysctls[] = { .data = &sysctl_hung_task_warnings, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec_minmax, + .proc_handler = proc_dohung_task_warnings, .extra1 = SYSCTL_NEG_ONE, }, { -- 2.55.0