Messages in this thread Patch in this message | | | From | Mathieu Desnoyers <> | Subject | [RFC PATCH for tip] sched: Fix concurrency ID handling of usermodehelper kthreads | Date | Mon, 2 Jan 2023 10:12:16 -0500 |
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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 <yujie.liu@intel.com> Link: https://lore.kernel.org/oe-lkp/202212301353.5c959d72-yujie.liu@intel.com 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
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