Process builders need to run setup in the child before its first return to userspace without storing a kernel callback in architecture-specific saved registers.
Allow an internal clone caller to supply task work. Queue it after the last ordinary fork failure check, while the child is still TASK_NEW. A NULL work pointer leaves existing clone callers unchanged. Assisted-by: Codex:gpt-5.6-sol Signed-off-by: Li Chen <[email protected]> --- include/linux/sched/task.h | 2 ++ kernel/fork.c | 6 ++++++ 2 files changed, 8 insertions(+) diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index 5b7facf12b33b..830de99aabaed 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -43,6 +43,8 @@ struct kernel_clone_args { int idle; int (*fn)(void *); void *fn_arg; + /* Run before the new task first returns to userspace. */ + struct callback_head *task_work; struct cgroup *cgrp; struct css_set *cset; bool embryonic_exec; diff --git a/kernel/fork.c b/kernel/fork.c index e3ade83b2d4e2..c0584eaa74711 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -109,6 +109,7 @@ #include <uapi/linux/pidfd.h> #include <linux/pidfs.h> #include <linux/tick.h> +#include <linux/task_work.h> #include <linux/unwind_deferred.h> #include <linux/pgalloc.h> #include <linux/uaccess.h> @@ -2504,6 +2505,11 @@ __latent_entropy struct task_struct *copy_process( retval = -EINTR; goto bad_fork_core_free; } + if (args->task_work) { + retval = task_work_add(p, args->task_work, TWA_RESUME); + if (WARN_ON_ONCE(retval)) + goto bad_fork_core_free; + } /* No more failure paths after this point. */ -- 2.52.0
