From 270750dbc18a71b23d660df110e433ff9616a2d4 Mon Sep 17 00:00:00 2001 From: Aaron Tomlin Date: Mon, 20 Jan 2014 17:34:13 +0000 Subject: hung_task: Display every hung task warning When khungtaskd detects hung tasks, it prints out backtraces from a number of those tasks. Limiting the number of backtraces being printed out can result in the user not seeing the information necessary to debug the issue. The hung_task_warnings sysctl controls this feature. This patch makes it possible for hung_task_warnings to accept a special value to print an unlimited number of backtraces when khungtaskd detects hung tasks. The special value is -1. To use this value it is necessary to change types from ulong to int. Signed-off-by: Aaron Tomlin Reviewed-by: Rik van Riel Acked-by: David Rientjes Cc: oleg@redhat.com Link: http://lkml.kernel.org/r/1390239253-24030-3-git-send-email-atomlin@redhat.com [ Build warning fix. ] Signed-off-by: Ingo Molnar --- kernel/hung_task.c | 6 ++++-- kernel/sysctl.c | 8 +++++--- 2 files changed, 9 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/hung_task.c b/kernel/hung_task.c index 9328b80eaf14..0b9c169d577f 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -37,7 +37,7 @@ int __read_mostly sysctl_hung_task_check_count = PID_MAX_LIMIT; */ unsigned long __read_mostly sysctl_hung_task_timeout_secs = CONFIG_DEFAULT_HUNG_TASK_TIMEOUT; -unsigned long __read_mostly sysctl_hung_task_warnings = 10; +int __read_mostly sysctl_hung_task_warnings = 10; static int __read_mostly did_panic; @@ -98,7 +98,9 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout) if (!sysctl_hung_task_warnings) return; - sysctl_hung_task_warnings--; + + if (sysctl_hung_task_warnings > 0) + sysctl_hung_task_warnings--; /* * Ok, the task did not get scheduled for more than 2 minutes, diff --git a/kernel/sysctl.c b/kernel/sysctl.c index c398a58673a7..dd5b4496637e 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -122,7 +122,8 @@ extern int blk_iopoll_enabled; static int sixty = 60; #endif -static int neg_one = -1; +static int __maybe_unused neg_one = -1; + static int zero; static int __maybe_unused one = 1; static int __maybe_unused two = 2; @@ -978,9 +979,10 @@ static struct ctl_table kern_table[] = { { .procname = "hung_task_warnings", .data = &sysctl_hung_task_warnings, - .maxlen = sizeof(unsigned long), + .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_doulongvec_minmax, + .proc_handler = proc_dointvec_minmax, + .extra1 = &neg_one, }, #endif #ifdef CONFIG_COMPAT -- cgit v1.2.3-58-ga151