The patch titled Subject: vfork: make it killable has been added to the -mm tree. Its filename is vfork-make-it-killable.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ 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 @@ -2396,7 +2396,7 @@ 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 @@ -690,10 +690,34 @@ 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. @@ -739,7 +763,8 @@ 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) && @@ -1583,6 +1608,7 @@ long do_fork(unsigned long clone_flags, if (clone_flags & CLONE_VFORK) { p->vfork_done = &vfork; init_completion(&vfork); + get_task_struct(p); } /* @@ -1600,10 +1626,8 @@ 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); _ Subject: Subject: vfork: make it killable Patches currently in -mm which might be from oleg@xxxxxxxxxx are 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 tile-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 s390-use-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 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 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 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 vfork-introduce-complete_vfork_done.patch vfork-make-it-killable.patch coredump_wait-dont-call-complete_vfork_done.patch vfork-kill-pf_starting.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 -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html