releases/4.4.181/net-avoid-weird-emergency-message.patch

   1 From foo@baz Wed 22 May 2019 07:38:16 PM CEST
   2 From: Eric Dumazet <edumazet@google.com>
   3 Date: Thu, 16 May 2019 08:09:57 -0700
   4 Subject: net: avoid weird emergency message
   5
   6 From: Eric Dumazet <edumazet@google.com>
   7
   8 [ Upstream commit d7c04b05c9ca14c55309eb139430283a45c4c25f ]
   9
  10 When host is under high stress, it is very possible thread
  11 running netdev_wait_allrefs() returns from msleep(250)
  12 10 seconds late.
  13
  14 This leads to these messages in the syslog :
  15
  16 [...] unregister_netdevice: waiting for syz_tun to become free. Usage count = 0
  17
  18 If the device refcount is zero, the wait is over.
  19
  20 Signed-off-by: Eric Dumazet <edumazet@google.com>
  21 Reported-by: syzbot <syzkaller@googlegroups.com>
  22 Signed-off-by: David S. Miller <davem@davemloft.net>
  23 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  24 ---
  25  net/core/dev.c |    2 +-
  26  1 file changed, 1 insertion(+), 1 deletion(-)
  27
  28 --- a/net/core/dev.c
  29 +++ b/net/core/dev.c
  30 @@ -6986,7 +6986,7 @@ static void netdev_wait_allrefs(struct n
  31
  32                 refcnt = netdev_refcnt_read(dev);
  33
  34 -               if (time_after(jiffies, warning_time + 10 * HZ)) {
  35 +               if (refcnt && time_after(jiffies, warning_time + 10 * HZ)) {
  36                         pr_emerg("unregister_netdevice: waiting for %s to become free. Usage count = %d\n",
  37                                  dev->name, refcnt);
  38                         warning_time = jiffies;