Re: [PATCH v3 6/6] freezer,sched: Rewrite core freezer logic

Peter Zijlstra
2022-09-26T18:25:08Z

On Mon, Sep 26, 2022 at 08:06:46PM +0200, Peter Zijlstra wrote:

> Let me go git-grep some to see if there's more similar fail.

I've ended up with the below...

---
include/linux/wait.h | 2 +-
kernel/hung_task.c | 8 ++++++--
kernel/sched/core.c | 2 +-
3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/include/linux/wait.h b/include/linux/wait.h
index 14ad8a0e9fac..7f5a51aae0a7 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -281,7 +281,7 @@ static inline void wake_up_pollfree(struct wait_queue_head *wq_head)

#define ___wait_is_interruptible(state) \
(!__builtin_constant_p(state) || \
- state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE) \
+ (state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))

extern void init_wait_entry(struct wait_queue_entry *wq_entry, int flags);

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index f1321c03c32a..4a8a713fd67b 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -191,6 +191,8 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
hung_task_show_lock = false;
rcu_read_lock();
for_each_process_thread(g, t) {
+ unsigned int state;
+
if (!max_count--)
goto unlock;
if (time_after(jiffies, last_break + HUNG_TASK_LOCK_BREAK)) {
@@ -198,8 +200,10 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
goto unlock;
last_break = jiffies;
}
- /* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
- if (READ_ONCE(t->__state) == TASK_UNINTERRUPTIBLE)
+ /* skip the TASK_KILLABLE tasks -- these can be killed */
+ state == READ_ONCE(t->__state);
+ if ((state & TASK_UNINTERRUPTIBLE) &&
+ !(state & TASK_WAKEKILL))
check_hung_task(t, timeout);
}
unlock:
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1095917ed048..12ee5b98e2c4 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8885,7 +8885,7 @@ state_filter_match(unsigned long state_filter, struct task_struct *p)
* When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows
* TASK_KILLABLE).
*/
- if (state_filter == TASK_UNINTERRUPTIBLE && state == TASK_IDLE)
+ if (state_filter == TASK_UNINTERRUPTIBLE && state & TASK_NOLOAD)
return false;

return true;