The quilt patch titled Subject: kernel/watchdog: always restore watchdog_softlockup(,hardlockup)_user_enabled after proc show has been removed from the -mm tree. Its filename was kernel-watchdog-always-restore-watchdog_softlockuphardlockup_user_enabled-after-proc-show.patch This patch was dropped because it was merged into the mm-nonmm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Tio Zhang <tiozhang@xxxxxxxxxxxxxx> Subject: kernel/watchdog: always restore watchdog_softlockup(,hardlockup)_user_enabled after proc show Date: Fri, 6 Sep 2024 17:47:00 +0800 Otherwise when watchdog_enabled becomes 0, watchdog_softlockup(,hardlockup)_user_enabled will changes to 0 after proc show. Steps to reproduce: step 1: # cat /proc/sys/kernel/*watchdog 1 1 1 | name | value |----------------------------------|-------------------------- | watchdog_enabled | 1 |----------------------------------|-------------------------- | watchdog_hardlockup_user_enabled | 1 |----------------------------------|-------------------------- | watchdog_softlockup_user_enabled | 1 |----------------------------------|-------------------------- | watchdog_user_enabled | 1 |----------------------------------|-------------------------- step 2: # echo 0 > /proc/sys/kernel/watchdog | name | value |----------------------------------|-------------------------- | watchdog_enabled | 0 |----------------------------------|-------------------------- | watchdog_hardlockup_user_enabled | 1 |----------------------------------|-------------------------- | watchdog_softlockup_user_enabled | 1 |----------------------------------|-------------------------- | watchdog_user_enabled | 0 |----------------------------------|-------------------------- step 3: # cat /proc/sys/kernel/*watchdog 0 0 0 | name | value |----------------------------------|-------------------------- | watchdog_enabled | 0 |----------------------------------|-------------------------- | watchdog_hardlockup_user_enabled | 0 |----------------------------------|-------------------------- | watchdog_softlockup_user_enabled | 0 |----------------------------------|-------------------------- | watchdog_user_enabled | 0 |----------------------------------|-------------------------- step 4: # echo 1 > /proc/sys/kernel/watchdog | name | value |----------------------------------|-------------------------- | watchdog_enabled | 0 |----------------------------------|-------------------------- | watchdog_hardlockup_user_enabled | 0 |----------------------------------|-------------------------- | watchdog_softlockup_user_enabled | 0 |----------------------------------|-------------------------- | watchdog_user_enabled | 0 |----------------------------------|-------------------------- step 5: # cat /proc/sys/kernel/*watchdog 0 0 0 If we dont do "step 3", do "step 4" right after "step 2", it will be | name | value |----------------------------------|-------------------------- | watchdog_enabled | 1 |----------------------------------|-------------------------- | watchdog_hardlockup_user_enabled | 1 |----------------------------------|-------------------------- | watchdog_softlockup_user_enabled | 1 |----------------------------------|-------------------------- | watchdog_user_enabled | 1 |----------------------------------|-------------------------- then everything works correctly. So this patch fix "step 3"'s value into | name | value |----------------------------------|-------------------------- | watchdog_enabled | 0 |----------------------------------|-------------------------- | watchdog_hardlockup_user_enabled | 1 |----------------------------------|-------------------------- | watchdog_softlockup_user_enabled | 1 |----------------------------------|-------------------------- | watchdog_user_enabled | 0 |----------------------------------|-------------------------- And still print 0 as before. Link: https://lkml.kernel.org/r/20240906094700.GA30052@didi-ThinkCentre-M930t-N000 Signed-off-by: Tio Zhang <tiozhang@xxxxxxxxxxxxxx> Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx> Cc: Ben Segall <bsegall@xxxxxxxxxx> Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx> Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: John Ogness <john.ogness@xxxxxxxxxxxxx> Cc: Juri Lelli <juri.lelli@xxxxxxxxxx> Cc: Krister Johansen <kjlx@xxxxxxxxxxxxxxxxxx> Cc: Li Zhe <lizhe.67@xxxxxxxxxxxxx> Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Thomas WeiÃ?schuh <linux@xxxxxxxxxxxxxx> Cc: Valentin Schneider <vschneid@xxxxxxxxxx> Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/watchdog.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/kernel/watchdog.c~kernel-watchdog-always-restore-watchdog_softlockuphardlockup_user_enabled-after-proc-show +++ a/kernel/watchdog.c @@ -990,6 +990,7 @@ static int proc_watchdog_common(int whic mutex_lock(&watchdog_mutex); + old = *param; if (!write) { /* * On read synchronize the userspace interface. This is a @@ -997,8 +998,8 @@ static int proc_watchdog_common(int whic */ *param = (watchdog_enabled & which) != 0; err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); + *param = old; } else { - old = READ_ONCE(*param); err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); if (!err && old != READ_ONCE(*param)) proc_watchdog_update(); _ Patches currently in -mm which might be from tiozhang@xxxxxxxxxxxxxx are