From f7505d64f2db5da2d7d94873ddf2cd2524847061 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Thu, 31 May 2012 16:26:21 -0700 Subject: [PATCH] fork: call complete_vfork_done() after clearing child_tid and flushing rss-counters Child should wake up the parent from vfork() only after finishing all operations with shared mm. There is no sense in using CLONE_CHILD_CLEARTID together with CLONE_VFORK, but it looks more accurate now. Signed-off-by: Konstantin Khlebnikov Cc: Oleg Nesterov Cc: Hugh Dickins Cc: KAMEZAWA Hiroyuki Cc: Konstantin Khlebnikov Cc: Markus Trippelsdorf Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/fork.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index 017fb23d5983..2254fbf23567 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -787,9 +787,6 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm) /* Get rid of any cached register state */ deactivate_mm(tsk, mm); - if (tsk->vfork_done) - complete_vfork_done(tsk); - /* * If we're exiting normally, clear a user-space tid field if * requested. We leave this alone when dying by signal, to leave @@ -810,6 +807,13 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm) } tsk->clear_child_tid = NULL; } + + /* + * All done, finally we can wake up parent and return this mm to him. + * Also kthread_stop() uses this completion for synchronization. + */ + if (tsk->vfork_done) + complete_vfork_done(tsk); } /* -- 2.20.1