From edd3cb05c00a040dc72bed20b14b5ba865188bce Mon Sep 17 00:00:00 2001 From: Simon Schuster Date: Mon, 1 Sep 2025 15:09:51 +0200 Subject: copy_process: pass clone_flags as u64 across calltree With the introduction of clone3 in commit 7f192e3cd316 ("fork: add clone3") the effective bit width of clone_flags on all architectures was increased from 32-bit to 64-bit, with a new type of u64 for the flags. However, for most consumers of clone_flags the interface was not changed from the previous type of unsigned long. While this works fine as long as none of the new 64-bit flag bits (CLONE_CLEAR_SIGHAND and CLONE_INTO_CGROUP) are evaluated, this is still undesirable in terms of the principle of least surprise. Thus, this commit fixes all relevant interfaces of callees to sys_clone3/copy_process (excluding the architecture-specific copy_thread) to consistently pass clone_flags as u64, so that no truncation to 32-bit integers occurs on 32-bit architectures. Signed-off-by: Simon Schuster Link: https://lore.kernel.org/20250901-nios2-implement-clone3-v2-2-53fcf5577d57@siemens-energy.com Acked-by: David Hildenbrand Reviewed-by: Lorenzo Stoakes Reviewed-by: Arnd Bergmann Signed-off-by: Christian Brauner --- include/linux/sched/task.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/sched/task.h') diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index ea41795a352b..34d6a0e108c3 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -63,7 +63,7 @@ extern int lockdep_tasklist_lock_is_held(void); extern asmlinkage void schedule_tail(struct task_struct *prev); extern void init_idle(struct task_struct *idle, int cpu); -extern int sched_fork(unsigned long clone_flags, struct task_struct *p); +extern int sched_fork(u64 clone_flags, struct task_struct *p); extern int sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs); extern void sched_cancel_fork(struct task_struct *p); extern void sched_post_fork(struct task_struct *p); -- cgit v1.2.3 From 39f17c707454290900b608ee5a200b5db9245626 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 14 Sep 2025 13:09:08 +0200 Subject: 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 Cc: Christian Brauner Cc: Jiri Slaby Cc: Mateusz Guzik Signed-off-by: Andrew Morton --- include/linux/sched/task.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'include/linux/sched/task.h') 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) { -- cgit v1.2.3