[RFC PATCH for tip] sched: Fix concurrency ID handling of usermodehelper kthreads
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: 2023-01-02 15:13:45
Also in:
lkml
Subsystem:
scheduler, the rest · Maintainers:
Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
sched_mm_cid_after_execve does not expect NULL t->mm, but it may happen
if a usermodehelper kthread fails when attempting to execute a binary.
sched_mm_cid_fork can be issued from a usermodehelper kthread, which has
t->flags PF_KTHREAD set.
Fixes: af7f588d8f73 ("sched: Introduce per-memory-map concurrency ID")
Reported-by: kernel test robot <redacted>
Link: https://lore.kernel.org/oe-lkp/202212301353.5c959d72-yujie.liu@intel.com (local)
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---
kernel/sched/core.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 048ec2417990..f99ee69867e3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c@@ -11343,8 +11343,8 @@ void sched_mm_cid_after_execve(struct task_struct *t) struct mm_struct *mm = t->mm; unsigned long flags; - WARN_ON_ONCE((t->flags & PF_KTHREAD) || !t->mm); - + if (!mm) + return; local_irq_save(flags); t->mm_cid = mm_cid_get(mm); t->mm_cid_active = 1;
@@ -11354,7 +11354,7 @@ void sched_mm_cid_after_execve(struct task_struct *t) void sched_mm_cid_fork(struct task_struct *t) { - WARN_ON_ONCE((t->flags & PF_KTHREAD) || !t->mm || t->mm_cid != -1); + WARN_ON_ONCE(!t->mm || t->mm_cid != -1); t->mm_cid_active = 1; } #endif
--
2.25.1