3.14-rc2: RECLAIM_FS-safe -> RECLAIM_FS-unsafe lock order detected

[Christian Kujau]

On Wed, 12 Feb 2014 at 00:11, Christian Kujau wrote:
> After upgrading from 3.13-rc8 to 3.14-rc2 on this PowerPC G4 machine, this 
> happened:

Yesterday a slighly different lockdep warning was printed:

 =========================================================
 [ INFO: possible irq lock inversion dependency detected ]
 3.14.0-rc2 #1 Tainted: G        W   
 ---------------------------------------------------------
 kswapd0/279 just changed the state of lock:
  (&(&ip->i_lock)->mr_lock){++++.?}, at: [<c01c213c>] 
xfs_free_eofblocks+0xe8/0x2e0
 but this lock took another, RECLAIM_FS-unsafe lock in the past:
  (&mm->mmap_sem){++++++}
 
 and interrupts could create inverse lock ordering between them.
 
 
 other info that might help us debug this:
  Possible interrupt unsafe locking scenario:
 
        CPU0                    CPU1
        ----                    ----
   lock(&mm->mmap_sem);
                                local_irq_disable();
                                lock(&(&ip->i_lock)->mr_lock);
                                lock(&mm->mmap_sem);
   <Interrupt>
     lock(&(&ip->i_lock)->mr_lock);
 
  *** DEADLOCK ***
 
 2 locks held by kswapd0/279:
  #0:  (shrinker_rwsem){++++..}, at: [<c00a5218>] shrink_slab+0x40/0x13c
  #1:  (&type->s_umount_key#36){+++++.}, at: [<c00d4840>] grab_super_passive+0x54/0xc0
 the shortest dependencies between 2nd lock and 1st lock:
  -> (&mm->mmap_sem){++++++} ops: 58148911 {
     HARDIRQ-ON-W at:
                       [<c0066b38>] lock_acquire+0x4c/0x68
                       [<c0558724>] down_write+0x4c/0x98
                       [<c00d88fc>] do_execve+0x2dc/0x574
                       [<c000425c>] try_to_run_init_process+0x18/0x58
                       [<c0004a48>] kernel_init+0xac/0x104
                       [<c0010ae4>] ret_from_kernel_thread+0x5c/0x64


...and on it goes, full dmesg: http://nerdbynature.de/bits/3.14-rc2/mm/

Thanks,
Christian.
-- 
BOFH excuse #65:

system needs to be rebooted