diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2025-09-14 13:09:08 +0200 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-09-22 20:10:59 -0700 |
| commit | 39f17c707454290900b608ee5a200b5db9245626 (patch) | |
| tree | 94b417d4f373570f43c3c9de06f542bc8aa0c7e9 | |
| parent | f23e76a32dbfc45418a1448f94886eb608b35b98 (diff) | |
sched/task.h: fix the wrong comment on task_lock() nesting with tasklist_lock
The ancient comment above task_lock() states that it can be nested outside
of read_lock(&tasklist_lock), but this is no longer true:
CPU_0 CPU_1 CPU_2
task_lock() read_lock(tasklist)
write_lock_irq(tasklist)
read_lock(tasklist) task_lock()
Unless CPU_0 calls read_lock() in IRQ context, queued_read_lock_slowpath()
won't get the lock immediately, it will spin waiting for the pending
writer on CPU_2, resulting in a deadlock.
Link: https://lkml.kernel.org/r/20250914110908.GA18769@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | include/linux/sched/task.h | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index ea41795a352b..8ff98b18b24b 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -210,9 +210,8 @@ static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t) * pins the final release of task.io_context. Also protects ->cpuset and * ->cgroup.subsys[]. And ->vfork_done. And ->sysvshm.shm_clist. * - * Nests both inside and outside of read_lock(&tasklist_lock). - * It must not be nested with write_lock_irq(&tasklist_lock), - * neither inside nor outside. + * Nests inside of read_lock(&tasklist_lock). It must not be nested with + * write_lock_irq(&tasklist_lock), neither inside nor outside. */ static inline void task_lock(struct task_struct *p) { |