The patch titled
Subject: vfork: make it killable
has been removed from the -mm tree. Its filename was
vfork-make-it-killable.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: vfork: make it killable
Make vfork() killable.
Change do_fork(CLONE_VFORK) to do wait_for_completion_killable(). If it
fails we do not return to the user-mode and never touch the memory shared
with our child.
However, in this case we should clear child->vfork_done before return, we
use task_lock() in do_fork()->wait_for_vfork_done() and
complete_vfork_done() to serialize with each other.
Note: now that we use task_lock() we don't really need completion, we
could turn task->vfork_done into "task_struct *wake_up_me" but this needs
some complications.
NOTE: this and the next patches do not affect in-kernel users of
CLONE_VFORK, kernel threads run with all signals ignored including
SIGKILL/SIGSTOP.
However this is obviously the user-visible change. Not only a fatal
signal can kill the vforking parent, a sub-thread can do execve or
exit_group() and kill the thread sleeping in vfork().
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/sched.h | 2 +-
kernel/fork.c | 40 ++++++++++++++++++++++++++++++++--------
2 files changed, 33 insertions(+), 9 deletions(-)
diff -puN include/linux/sched.h~vfork-make-it-killable include/linux/sched.h
--- a/include/linux/sched.h~vfork-make-it-killable
+++ a/include/linux/sched.h
@@ -2372,7 +2372,7 @@ static inline int thread_group_empty(str
* Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
* subscriptions and synchronises with wait4(). Also used in procfs. Also
* pins the final release of task.io_context. Also protects ->cpuset and
- * ->cgroup.subsys[].
+ * ->cgroup.subsys[]. And ->vfork_done.
*
* Nests both inside and outside of read_lock(&tasklist_lock).
* It must not be nested with write_lock_irq(&tasklist_lock),
diff -puN kernel/fork.c~vfork-make-it-killable kernel/fork.c
--- a/kernel/fork.c~vfork-make-it-killable
+++ a/kernel/fork.c
@@ -670,10 +670,34 @@ struct mm_struct *mm_access(struct task_
void complete_vfork_done(struct task_struct *tsk)
{
- struct completion *vfork_done = tsk->vfork_done;
+ struct completion *vfork;
- tsk->vfork_done = NULL;
- complete(vfork_done);
+ task_lock(tsk);
+ vfork = tsk->vfork_done;
+ if (likely(vfork)) {
+ tsk->vfork_done = NULL;
+ complete(vfork);
+ }
+ task_unlock(tsk);
+}
+
+static int wait_for_vfork_done(struct task_struct *child,
+ struct completion *vfork)
+{
+ int killed;
+
+ freezer_do_not_count();
+ killed = wait_for_completion_killable(vfork);
+ freezer_count();
+
+ if (killed) {
+ task_lock(child);
+ child->vfork_done = NULL;
+ task_unlock(child);
+ }
+
+ put_task_struct(child);
+ return killed;
}
/* Please note the differences between mmput and mm_release.
@@ -717,7 +741,8 @@ void mm_release(struct task_struct *tsk,
* If we're exiting normally, clear a user-space tid field if
* requested. We leave this alone when dying by signal, to leave
* the value intact in a core dump, and to save the unnecessary
- * trouble otherwise. Userland only wants this done for a sys_exit.
+ * trouble, say, a killed vfork parent shouldn't touch this mm.
+ * Userland only wants this done for a sys_exit.
*/
if (tsk->clear_child_tid) {
if (!(tsk->flags & PF_SIGNALED) &&
@@ -1551,6 +1576,7 @@ long do_fork(unsigned long clone_flags,
if (clone_flags & CLONE_VFORK) {
p->vfork_done = &vfork;
init_completion(&vfork);
+ get_task_struct(p);
}
/*
@@ -1568,10 +1594,8 @@ long do_fork(unsigned long clone_flags,
ptrace_event(trace, nr);
if (clone_flags & CLONE_VFORK) {
- freezer_do_not_count();
- wait_for_completion(&vfork);
- freezer_count();
- ptrace_event(PTRACE_EVENT_VFORK_DONE, nr);
+ if (!wait_for_vfork_done(p, &vfork))
+ ptrace_event(PTRACE_EVENT_VFORK_DONE, nr);
}
} else {
nr = PTR_ERR(p);
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
linux-next.patch
arm-use-set_current_blocked-and-block_sigmask.patch
avr32-dont-mask-signals-in-the-error-path.patch
avr32-use-set_current_blocked-in-handle_signal-sys_rt_sigreturn.patch
avr32-use-block_sigmask.patch
powerpc-use-set_current_blocked-and-block_sigmask.patch
hexagon-use-set_current_blocked-and-block_sigmask.patch
ia64-use-set_current_blocked-and-block_sigmask.patch
microblaze-dont-reimplement-force_sigsegv.patch
microblaze-no-need-to-reset-handler-if-sa_oneshot.patch
microblaze-fix-signal-masking.patch
microblaze-use-set_current_blocked-and-block_sigmask.patch
mips-use-set_current_blocked-and-block_sigmask.patch
score-dont-mask-signals-if-we-fail-to-setup-signal-stack.patch
score-use-set_current_blocked-and-block_sigmask.patch
unicore32-use-block_sigmask.patch
blackfin-use-set_current_blocked-and-block_sigmask.patch
parisc-use-set_current_blocked-and-block_sigmask.patch
xtensa-dont-reimplement-force_sigsegv.patch
xtensa-no-need-to-reset-handler-if-sa_oneshot.patch
xtensa-dont-mask-signals-if-we-fail-to-setup-signal-stack.patch
xtensa-use-set_current_blocked-and-block_sigmask.patch
sparc-use-block_sigmask.patch
procfs-mark-thread-stack-correctly-in-proc-pid-maps.patch
frv-use-set_current_blocked-and-block_sigmask.patch
sh-no-need-to-reset-handler-if-sa_oneshot.patch
sh-use-set_current_blocked-and-block_sigmask.patch
h8300-use-set_current_blocked-and-block_sigmask.patch
alpha-use-set_current_blocked-and-block_sigmask.patch
m32r-use-set_current_blocked-and-block_sigmask.patch
m68k-use-set_current_blocked-and-block_sigmask.patch
mn10300-use-set_current_blocked-and-block_sigmask.patch
c6x-use-set_current_blocked-and-block_sigmask.patch
cris-use-set_current_blocked-and-block_sigmask.patch
um-dont-restore-current-blocked-on-error.patch
um-use-set_current_blocked-and-block_sigmask.patch
prctl-add-pr_setget_child_subreaper-to-allow-simple-process-supervision.patch
prctl-add-pr_setget_child_subreaper-to-allow-simple-process-supervision-fix.patch
prctl-add-pr_setget_child_subreaper-to-allow-simple-process-supervision-fix-fix.patch
kernel-exitc-if-init-dies-log-a-signal-which-killed-it-if-any.patch
kernel-exitc-if-init-dies-log-a-signal-which-killed-it-if-any-fix.patch
powerpc-eeh-remove-eeh_event_handler-daemonize.patch
ptrace-the-killed-tracee-should-not-enter-the-syscall.patch
ptrace-dont-send-sigtrap-on-exec-if-seized.patch
ptrace-dont-modify-flags-on-ptrace_setoptions-failure.patch
ptrace-simplify-ptrace_foo-constants-and-ptrace_setoptions-code.patch
ptrace-make-ptrace_seize-set-ptrace-options-specified-in-data-parameter.patch
ptrace-renumber-ptrace_event_stop-so-that-future-new-options-and-events-can-match.patch
ptrace-remove-ptrace_seize_devel-bit.patch
tile-use-set_current_blocked-and-block_sigmask.patch
signal-give-send_sig_forced-more-power-to-beat-signal_unkillable.patch
signal-cosmetic-s-from_ancestor_ns-force-in-prepare_signal-paths.patch
signal-oom_kill_task-use-send_sig_forced-instead-of-force_sig.patch
signal-zap_pid_ns_processes-s-send_sig_noinfo-send_sig_forced.patch
usermodehelper-use-umh_wait_proc-consistently.patch
usermodehelper-introduce-umh_completesub_info.patch
usermodehelper-implement-umh_killable.patch
usermodehelper-kill-umh_wait-renumber-umh_-constants.patch
usermodehelper-____call_usermodehelper-doesnt-need-do_exit.patch
kmod-introduce-call_modprobe-helper.patch
kmod-make-__request_module-killable.patch
pidns-add-reboot_pid_ns-to-handle-the-reboot-syscall.patch
pidns-add-reboot_pid_ns-to-handle-the-reboot-syscall-fix.patch
sysctl-make-kernelns_last_pid-control-being-checkpoint_restore-dependent.patch
fs-proc-introduce-proc-pid-task-tid-children-entry-v9.patch
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