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| author |   Peter Zijlstra <peterz@infradead.org> | 2022-09-27 21:02:34 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-09-28 10:00:16 +0200 |
| commit | 5aec788aeb8eb74282b75ac1b317beb0fbb69a42 (patch) | |
| tree | 0b191d9fffa590cbca17596e8c8c1147a42d14dc | |
| parent | sched/fair: Move call to list_last_entry() in detach_tasks (diff) | |
| download | linux-dev-5aec788aeb8eb74282b75ac1b317beb0fbb69a42.tar.xz linux-dev-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>
| -rw-r--r-- | include/linux/wait.h | 2 | ||||
| -rw-r--r-- | kernel/hung_task.c | 8 | ||||
| -rw-r--r-- | 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..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: diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4fa4a3ddb4f4..02dc1b8e3cb6 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8884,7 +8884,7 @@ 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; |