6.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Krister Johansen kjlx@templeofstupid.com
commit 8b793bcda61f6c3ed4f5b2ded7530ef6749580cb upstream.
Setting softlockup_panic from do_sysctl_args() causes it to take effect later in boot. The lockup detector is enabled before SMP is brought online, but do_sysctl_args runs afterwards. If a user wants to set softlockup_panic on boot and have it trigger should a softlockup occur during onlining of the non-boot processors, they could do this prior to commit f117955a2255 ("kernel/watchdog.c: convert {soft/hard}lockup boot parameters to sysctl aliases"). However, after this commit the value of softlockup_panic is set too late to be of help for this type of problem. Restore the prior behavior.
Signed-off-by: Krister Johansen kjlx@templeofstupid.com Cc: stable@vger.kernel.org Fixes: f117955a2255 ("kernel/watchdog.c: convert {soft/hard}lockup boot parameters to sysctl aliases") Signed-off-by: Luis Chamberlain mcgrof@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/proc/proc_sysctl.c | 1 - kernel/watchdog.c | 7 +++++++ 2 files changed, 7 insertions(+), 1 deletion(-)
--- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -1574,7 +1574,6 @@ static const struct sysctl_alias sysctl_ {"hung_task_panic", "kernel.hung_task_panic" }, {"numa_zonelist_order", "vm.numa_zonelist_order" }, {"softlockup_all_cpu_backtrace", "kernel.softlockup_all_cpu_backtrace" }, - {"softlockup_panic", "kernel.softlockup_panic" }, { } };
--- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -283,6 +283,13 @@ static DEFINE_PER_CPU(struct hrtimer, wa static DEFINE_PER_CPU(bool, softlockup_touch_sync); static unsigned long soft_lockup_nmi_warn;
+static int __init softlockup_panic_setup(char *str) +{ + softlockup_panic = simple_strtoul(str, NULL, 0); + return 1; +} +__setup("softlockup_panic=", softlockup_panic_setup); + static int __init nowatchdog_setup(char *str) { watchdog_user_enabled = 0;