Subject: + wait-use-exit_trace-only-if-thread_group_leaderzombie.patch added to -mm tree To: oleg@xxxxxxxxxx,jan.kratochvil@xxxxxxxxxx,lpoetter@xxxxxxxxxx,mschmidt@xxxxxxxxxx,roland@xxxxxxxxxxxxx,tj@xxxxxxxxxx,viro@xxxxxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Fri, 21 Feb 2014 13:39:19 -0800 The patch titled Subject: wait: use EXIT_TRACE only if thread_group_leader(zombie) has been added to the -mm tree. Its filename is wait-use-exit_trace-only-if-thread_group_leaderzombie.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/wait-use-exit_trace-only-if-thread_group_leaderzombie.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/wait-use-exit_trace-only-if-thread_group_leaderzombie.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: wait: use EXIT_TRACE only if thread_group_leader(zombie) wait_task_zombie() always uses EXIT_TRACE/ptrace_unlink() if ptrace_reparented(). This is suboptimal and a bit confusing: we do not need do_notify_parent(p) if !thread_group_leader(p) and in this case we also do not need ptrace_unlink(), we can rely on ptrace_release_task(). Change wait_task_zombie() to check thread_group_leader() along with ptrace_reparented() and simplify the final p->exit_state transition. Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Tested-by: Michal Schmidt <mschmidt@xxxxxxxxxx> Cc: Jan Kratochvil <jan.kratochvil@xxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Lennart Poettering <lpoetter@xxxxxxxxxx> Cc: Roland McGrath <roland@xxxxxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/exit.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff -puN kernel/exit.c~wait-use-exit_trace-only-if-thread_group_leaderzombie kernel/exit.c --- a/kernel/exit.c~wait-use-exit_trace-only-if-thread_group_leaderzombie +++ a/kernel/exit.c @@ -1042,7 +1042,7 @@ static int wait_task_zombie(struct wait_ /* * Move the task's state to DEAD/TRACE, only one thread can do this. */ - state = traced ? EXIT_TRACE : EXIT_DEAD; + state = traced && thread_group_leader(p) ? EXIT_TRACE : EXIT_DEAD; if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) return 0; /* @@ -1142,18 +1142,15 @@ static int wait_task_zombie(struct wait_ if (!retval) retval = pid; - if (traced) { + if (state == EXIT_TRACE) { write_lock_irq(&tasklist_lock); /* We dropped tasklist, ptracer could die and untrace */ ptrace_unlink(p); - /* - * If this is not a sub-thread, notify the parent. - * If parent wants a zombie, don't release it now. - */ - state = EXIT_DEAD; - if (thread_group_leader(p) && - !do_notify_parent(p, p->exit_signal)) - state = EXIT_ZOMBIE; + + /* If parent wants a zombie, don't release it now */ + state = EXIT_ZOMBIE; + if (do_notify_parent(p, p->exit_signal)) + state = EXIT_DEAD; p->exit_state = state; write_unlock_irq(&tasklist_lock); } _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are kthread-ensure-locality-of-task_struct-allocations.patch wait-fix-reparent_leader-vs-exit_dead-exit_zombie-race.patch wait-introduce-exit_trace-to-avoid-the-racy-exit_dead-exit_zombie-transition.patch wait-use-exit_trace-only-if-thread_group_leaderzombie.patch wait-completely-ignore-the-exit_dead-tasks.patch wait-swap-exit_zombie-and-exit_dead-to-hide-exit_trace-from-user-space.patch linux-next.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