The patch titled
do_wait-wakeup-optimization: fix child_wait_callback()->eligible_child() usage
has been added to the -mm tree. Its filename is
do_wait-wakeup-optimization-fix-child_wait_callback-eligible_child-usage.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 ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: do_wait-wakeup-optimization: fix child_wait_callback()->eligible_child() usage
From: Oleg Nesterov <oleg@xxxxxxxxxx>
child_wait_callback()->eligible_child() is not right, we can miss the
wakeup if the task was detached before __wake_up_parent() and the caller
of do_wait() didn't use __WALL.
Move ->wo_pid checks from eligible_child() to the new helper,
eligible_pid(), and change child_wait_callback() to use it instead of
eligible_child().
Note: actually I think it would be better to fix the __WCLONE check in
eligible_child(), it doesn't look exactly right. But it is not clear what
is the supposed behaviour, and any change is user-visible.
Reported-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/exit.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff -puN kernel/exit.c~do_wait-wakeup-optimization-fix-child_wait_callback-eligible_child-usage kernel/exit.c
--- a/kernel/exit.c~do_wait-wakeup-optimization-fix-child_wait_callback-eligible_child-usage
+++ a/kernel/exit.c
@@ -1106,13 +1106,16 @@ static struct pid *task_pid_type(struct
return pid;
}
-static int eligible_child(struct wait_opts *wo, struct task_struct *p)
+static inline int eligible_pid(struct wait_opts *wo, struct task_struct *p)
{
- if (wo->wo_type < PIDTYPE_MAX) {
- if (task_pid_type(p, wo->wo_type) != wo->wo_pid)
- return 0;
- }
+ return wo->wo_type == PIDTYPE_MAX ||
+ task_pid_type(p, wo->wo_type) == wo->wo_pid;
+}
+static int eligible_child(struct wait_opts *wo, struct task_struct *p)
+{
+ if (!eligible_pid(wo, p))
+ return 0;
/* Wait for all children (clone and not) if __WALL is set;
* otherwise, wait for clone children *only* if __WCLONE is
* set; otherwise, wait for non-clone children *only*. (Note:
@@ -1573,7 +1576,7 @@ static int child_wait_callback(wait_queu
child_wait);
struct task_struct *p = key;
- if (!eligible_child(wo, p))
+ if (!eligible_pid(wo, p))
return 0;
if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
linux-next.patch
oom-move-oom_adj-value-from-task_struct-to-signal_struct.patch
oom-make-oom_score-to-per-process-value.patch
oom-oom_kill-doesnt-kill-vfork-parentor-child.patch
oom-fix-oom_adjust_write-input-sanity-check.patch
getrusage-fill-ru_maxrss-value.patch
getrusage-fill-ru_maxrss-value-update.patch
proc_flush_task-flush-proc-tid-task-pid-when-a-sub-thread-exits.patch
cgroups-revert-cgroups-fix-pid-namespace-bug.patch
cgroups-add-a-read-only-procs-file-similar-to-tasks-that-shows-only-unique-tgids.patch
cgroups-ensure-correct-concurrent-opening-reading-of-pidlists-across-pid-namespaces.patch
cgroups-use-vmalloc-for-large-cgroups-pidlist-allocations.patch
cgroups-change-css_set-freeing-mechanism-to-be-under-rcu.patch
cgroups-let-ss-can_attach-and-ss-attach-do-whole-threadgroups-at-a-time.patch
cgroups-let-ss-can_attach-and-ss-attach-do-whole-threadgroups-at-a-time-fix.patch
cgroups-add-functionality-to-read-write-lock-clone_thread-forking-per-threadgroup.patch
cgroups-add-functionality-to-read-write-lock-clone_thread-forking-per-threadgroup-fix.patch
cgroups-add-ability-to-move-all-threads-in-a-process-to-a-new-cgroup-atomically.patch
ptrace-__ptrace_detach-do-__wake_up_parent-if-we-reap-the-tracee.patch
do_wait-wakeup-optimization-shift-security_task_wait-from-eligible_child-to-wait_consider_task.patch
do_wait-wakeup-optimization-change-__wake_up_parent-to-use-filtered-wakeup.patch
do_wait-wakeup-optimization-change-__wake_up_parent-to-use-filtered-wakeup-selinux_bprm_committed_creds-use-__wake_up_parent.patch
do_wait-wakeup-optimization-child_wait_callback-check-__wnothread-case.patch
do_wait-wakeup-optimization-fix-child_wait_callback-eligible_child-usage.patch
do_wait-wakeup-optimization-simplify-task_pid_type.patch
do_wait-optimization-do-not-place-sub-threads-on-task_struct-children-list.patch
wait_consider_task-kill-parent-argument.patch
do_wait-fix-sys_waitid-specific-behaviour.patch
wait_noreap_copyout-check-for-wo_info-=-null.patch
signals-introduce-do_send_sig_info-helper.patch
signals-send_sigio-use-do_send_sig_info-to-avoid-check_kill_permission.patch
fcntl-add-f_etown_ex.patch
signals-inline-__fatal_signal_pending.patch
signals-tracehook_notify_jctl-change.patch
signals-tracehook_notify_jctl-change-do_signal_stop-do-not-call-tracehook_notify_jctl-in-task_stopped-state.patch
signals-introduce-tracehook_finish_jctl-helper.patch
utrace-core.patch
exec-fix-set_binfmt-vs-sys_delete_module-race.patch
fork-disable-clone_parent-for-init.patch
pidns-deny-clone_parentclone_newpid-combination.patch
task_struct-cleanup-move-binfmt-field-to-mm_struct.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
