mm: correctly synchronize rss-counters at exit/exec
authorKonstantin Khlebnikov <khlebnikov@openvz.org>
Wed, 20 Jun 2012 19:53:01 +0000 (12:53 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 16 Jul 2012 16:04:08 +0000 (09:04 -0700)
commit21017faf87a93117ca7a14aa8f0dd2f315fdeb08
treedbdd62ebc0e69df1992f2c14cba75fce37a2bef1
parenta7c60136e5bf96bc58a27ab9822a2e48ed768429
mm: correctly synchronize rss-counters at exit/exec

commit 4fe7efdbdfb1c7e7a7f31decfd831c0f31d37091 upstream.

do_exit() and exec_mmap() call sync_mm_rss() before mm_release() does
put_user(clear_child_tid) which can update task->rss_stat and thus make
mm->rss_stat inconsistent.  This triggers the "BUG:" printk in check_mm().

Let's fix this bug in the safest way, and optimize/cleanup this later.

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fs/exec.c
kernel/exit.c