rt-patches/0287-mm-backing-dev-don-t-disable-IRQs-in-wb_congested_pu.patch

   1 From 62d0f0ee8aeef0320502bf7b5805d4557ddb952d Mon Sep 17 00:00:00 2001
   2 From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
   3 Date: Fri, 5 Feb 2016 12:17:14 +0100
   4 Subject: [PATCH 287/366] mm: backing-dev: don't disable IRQs in
   5  wb_congested_put()
   6
   7 it triggers:
   8 |BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:930
   9 |in_atomic(): 0, irqs_disabled(): 1, pid: 12, name: rcuc/0
  10 |1 lock held by rcuc/0/12:
  11 | #0:  (rcu_callback){......}, at: [<ffffffff810ce1a6>] rcu_cpu_kthread+0x376/0xb10
  12 |irq event stamp: 23636
  13 |hardirqs last  enabled at (23635): [<ffffffff8173524c>] _raw_spin_unlock_irqrestore+0x6c/0x80
  14 |hardirqs last disabled at (23636): [<ffffffff81173918>] wb_congested_put+0x18/0x90
  15 | [<ffffffff81735434>] rt_spin_lock+0x24/0x60
  16 | [<ffffffff810afed2>] atomic_dec_and_spin_lock+0x52/0x90
  17 | [<ffffffff81173928>] wb_congested_put+0x28/0x90
  18 | [<ffffffff813b833e>] __blkg_release_rcu+0x5e/0x1e0
  19 | [<ffffffff813b8367>] ? __blkg_release_rcu+0x87/0x1e0
  20 | [<ffffffff813b82e0>] ? blkg_conf_finish+0x90/0x90
  21 | [<ffffffff810ce1e7>] rcu_cpu_kthread+0x3b7/0xb10
  22
  23 due to cgwb_lock beeing taken with spin_lock_irqsave() usually.
  24
  25 Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
  26 ---
  27  mm/backing-dev.c | 4 ++--
  28  1 file changed, 2 insertions(+), 2 deletions(-)
  29
  30 diff --git a/mm/backing-dev.c b/mm/backing-dev.c
  31 index 9ef80bf..826fed5 100644
  32 --- a/mm/backing-dev.c
  33 +++ b/mm/backing-dev.c
  34 @@ -457,9 +457,9 @@ void wb_congested_put(struct bdi_writeback_congested *congested)
  35  {
  36         unsigned long flags;
  37
  38 -       local_irq_save(flags);
  39 +       local_irq_save_nort(flags);
  40         if (!atomic_dec_and_lock(&congested->refcnt, &cgwb_lock)) {
  41 -               local_irq_restore(flags);
  42 +               local_irq_restore_nort(flags);
  43                 return;
  44         }
  45
  46 --
  47 1.9.1
  48