* management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
*/
+#include <linux/anon_inodes.h>
#include <linux/slab.h>
#include <linux/sched/autogroup.h>
#include <linux/sched/mm.h>
#include <linux/sched/task.h>
#include <linux/sched/task_stack.h>
#include <linux/sched/cputime.h>
+#include <linux/seq_file.h>
#include <linux/rtmutex.h>
#include <linux/init.h>
#include <linux/unistd.h>
#endif
}
+static __always_inline void mm_clear_owner(struct mm_struct *mm,
+ struct task_struct *p)
+{
+#ifdef CONFIG_MEMCG
+ if (mm->owner == p)
+ WRITE_ONCE(mm->owner, NULL);
+#endif
+}
+
static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
{
#ifdef CONFIG_MEMCG
int killed;
freezer_do_not_count();
+ cgroup_enter_frozen();
killed = wait_for_completion_killable(vfork);
+ cgroup_leave_frozen(false);
freezer_count();
if (killed) {
free_pt:
/* don't put binfmt in mmput, we haven't got module yet */
mm->binfmt = NULL;
+ mm_init_owner(mm, NULL);
mmput(mm);
fail_nomem:
#endif /* #ifdef CONFIG_TASKS_RCU */
}
+static int pidfd_release(struct inode *inode, struct file *file)
+{
+ struct pid *pid = file->private_data;
+
+ file->private_data = NULL;
+ put_pid(pid);
+ return 0;
+}
+
+#ifdef CONFIG_PROC_FS
+static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
+{
+ struct pid_namespace *ns = proc_pid_ns(file_inode(m->file));
+ struct pid *pid = f->private_data;
+
+ seq_put_decimal_ull(m, "Pid:\t", pid_nr_ns(pid, ns));
+ seq_putc(m, '\n');
+}
+#endif
+
+const struct file_operations pidfd_fops = {
+ .release = pidfd_release,
+#ifdef CONFIG_PROC_FS
+ .show_fdinfo = pidfd_show_fdinfo,
+#endif
+};
+
+/**
+ * pidfd_create() - Create a new pid file descriptor.
+ *
+ * @pid: struct pid that the pidfd will reference
+ *
+ * This creates a new pid file descriptor with the O_CLOEXEC flag set.
+ *
+ * Note, that this function can only be called after the fd table has
+ * been unshared to avoid leaking the pidfd to the new process.
+ *
+ * Return: On success, a cloexec pidfd is returned.
+ * On error, a negative errno number will be returned.
+ */
+static int pidfd_create(struct pid *pid)
+{
+ int fd;
+
+ fd = anon_inode_getfd("[pidfd]", &pidfd_fops, get_pid(pid),
+ O_RDWR | O_CLOEXEC);
+ if (fd < 0)
+ put_pid(pid);
+
+ return fd;
+}
+
+static void __delayed_free_task(struct rcu_head *rhp)
+{
+ struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
+
+ free_task(tsk);
+}
+
+static __always_inline void delayed_free_task(struct task_struct *tsk)
+{
+ if (IS_ENABLED(CONFIG_MEMCG))
+ call_rcu(&tsk->rcu, __delayed_free_task);
+ else
+ free_task(tsk);
+}
+
/*
* This creates a new process as a copy of the old one,
* but does not actually start it yet.
unsigned long clone_flags,
unsigned long stack_start,
unsigned long stack_size,
+ int __user *parent_tidptr,
int __user *child_tidptr,
struct pid *pid,
int trace,
unsigned long tls,
int node)
{
- int retval;
+ int pidfd = -1, retval;
struct task_struct *p;
struct multiprocess_signals delayed;
return ERR_PTR(-EINVAL);
}
+ if (clone_flags & CLONE_PIDFD) {
+ int reserved;
+
+ /*
+ * - CLONE_PARENT_SETTID is useless for pidfds and also
+ * parent_tidptr is used to return pidfds.
+ * - CLONE_DETACHED is blocked so that we can potentially
+ * reuse it later for CLONE_PIDFD.
+ * - CLONE_THREAD is blocked until someone really needs it.
+ */
+ if (clone_flags &
+ (CLONE_DETACHED | CLONE_PARENT_SETTID | CLONE_THREAD))
+ return ERR_PTR(-EINVAL);
+
+ /*
+ * Verify that parent_tidptr is sane so we can potentially
+ * reuse it later.
+ */
+ if (get_user(reserved, parent_tidptr))
+ return ERR_PTR(-EFAULT);
+
+ if (reserved != 0)
+ return ERR_PTR(-EINVAL);
+ }
+
/*
* Force any signals received before this point to be delivered
* before the fork happens. Collect up signals sent to multiple
}
}
+ /*
+ * This has to happen after we've potentially unshared the file
+ * descriptor table (so that the pidfd doesn't leak into the child
+ * if the fd table isn't shared).
+ */
+ if (clone_flags & CLONE_PIDFD) {
+ retval = pidfd_create(pid);
+ if (retval < 0)
+ goto bad_fork_free_pid;
+
+ pidfd = retval;
+ retval = put_user(pidfd, parent_tidptr);
+ if (retval)
+ goto bad_fork_put_pidfd;
+ }
+
#ifdef CONFIG_BLOCK
p->plug = NULL;
#endif
#ifdef TIF_SYSCALL_EMU
clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
#endif
- clear_all_latency_tracing(p);
+ clear_tsk_latency_tracing(p);
/* ok, now we should be set up.. */
p->pid = pid_nr(pid);
*/
retval = cgroup_can_fork(p);
if (retval)
- goto bad_fork_free_pid;
+ goto bad_fork_cgroup_threadgroup_change_end;
/*
* From this point on we must avoid any synchronous user-space
spin_unlock(¤t->sighand->siglock);
write_unlock_irq(&tasklist_lock);
cgroup_cancel_fork(p);
-bad_fork_free_pid:
+bad_fork_cgroup_threadgroup_change_end:
cgroup_threadgroup_change_end(current);
+bad_fork_put_pidfd:
+ if (clone_flags & CLONE_PIDFD)
+ ksys_close(pidfd);
+bad_fork_free_pid:
if (pid != &init_struct_pid)
free_pid(pid);
bad_fork_cleanup_thread:
bad_fork_cleanup_namespaces:
exit_task_namespaces(p);
bad_fork_cleanup_mm:
- if (p->mm)
+ if (p->mm) {
+ mm_clear_owner(p->mm, p);
mmput(p->mm);
+ }
bad_fork_cleanup_signal:
if (!(clone_flags & CLONE_THREAD))
free_signal_struct(p->signal);
bad_fork_free:
p->state = TASK_DEAD;
put_task_stack(p);
- free_task(p);
+ delayed_free_task(p);
fork_out:
spin_lock_irq(¤t->sighand->siglock);
hlist_del_init(&delayed.node);
struct task_struct *fork_idle(int cpu)
{
struct task_struct *task;
- task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0, 0,
+ task = copy_process(CLONE_VM, 0, 0, NULL, NULL, &init_struct_pid, 0, 0,
cpu_to_node(cpu));
if (!IS_ERR(task)) {
init_idle_pids(task);
trace = 0;
}
- p = copy_process(clone_flags, stack_start, stack_size,
+ p = copy_process(clone_flags, stack_start, stack_size, parent_tidptr,
child_tidptr, NULL, trace, tls, NUMA_NO_NODE);
add_latent_entropy();
projects / linux-2.6-microblaze.git / blobdiff