Messages in this thread Patch in this message | | | Date | Sun, 13 Jun 2010 19:13:37 +0200 | From | Oleg Nesterov <> | Subject | uninterruptible CLONE_VFORK (Was: oom: Make coredump interruptible) |
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On 06/13, Oleg Nesterov wrote: > > On 06/13, KOSAKI Motohiro wrote: > > > > But, again, I have no objection to your patch. because I really hope to > > fix coredump vs oom issue. > > Yes, I think this is important.
Oh. And another problem, vfork() is not interruptible too. This means that the user can hide the memory hog from oom-killer. But let's forget about oom.
Roland, any reason it should be uninterruptible? This doesn't look good in any case. Perhaps the pseudo-patch below makes sense?
Oleg.
--- x/kernel/fork.c +++ x/kernel/fork.c @@ -1359,6 +1359,26 @@ struct task_struct * __cpuinit fork_idle return task; } +// --------------------------------------------------- +// THIS SHOULD BE USED BY mm_release/coredump_wait/etc +// --------------------------------------------------- +void complete_vfork_done(struct task_struct *tsk) +{ + struct completion *vfork = xchg(tsk->vfork_done, NULL); + if (vfork) + complete(vfork); +} + +static wait_for_vfork_done(struct task_struct *child, struct completion *vfork) +{ + if (!wait_for_completion_killable(vfork)) + return; + if (xchg(child->vfork_done, NULL) != NULL) + return; + // the child has already read ->vfork_done and it should wake us up + wait_for_completion(vfork); +} + /* * Ok, this is the main fork-routine. * @@ -1433,6 +1453,7 @@ long do_fork(unsigned long clone_flags, if (clone_flags & CLONE_VFORK) { p->vfork_done = &vfork; init_completion(&vfork); + get_task_struct(p); } audit_finish_fork(p); @@ -1462,7 +1483,8 @@ long do_fork(unsigned long clone_flags, if (clone_flags & CLONE_VFORK) { freezer_do_not_count(); - wait_for_completion(&vfork); + wait_for_vfork_done(p, &vfork); + put_task_struct(p), freezer_count(); tracehook_report_vfork_done(p, nr); }
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