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authorPeter Zijlstra <peterz@infradead.org>2022-09-27 21:02:34 +0200
committerPeter Zijlstra <peterz@infradead.org>2022-09-28 10:00:16 +0200
commit5aec788aeb8eb74282b75ac1b317beb0fbb69a42 (patch)
tree0b191d9fffa590cbca17596e8c8c1147a42d14dc /kernel/hung_task.c
parentsched/fair: Move call to list_last_entry() in detach_tasks (diff)
downloadlinux-5aec788aeb8eb74282b75ac1b317beb0fbb69a42.tar.xz
linux-5aec788aeb8eb74282b75ac1b317beb0fbb69a42.zip
sched: Fix TASK_state comparisons
Task state is fundamentally a bitmask; direct comparisons are probably not working as intended. Specifically the normal wait-state have a number of possible modifiers: TASK_UNINTERRUPTIBLE: TASK_WAKEKILL, TASK_NOLOAD, TASK_FREEZABLE TASK_INTERRUPTIBLE: TASK_FREEZABLE Specifically, the addition of TASK_FREEZABLE wrecked __wait_is_interruptible(). This however led to an audit of direct comparisons yielding the rest of the changes. Fixes: f5d39b020809 ("freezer,sched: Rewrite core freezer logic") Reported-by: Christian Borntraeger <borntraeger@linux.ibm.com> Debugged-by: Christian Borntraeger <borntraeger@linux.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Diffstat (limited to 'kernel/hung_task.c')
-rw-r--r--kernel/hung_task.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index f1321c03c32a..3a15169ba2f8 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: