On Mon, 3 Feb 2014, Paul E. McKenney wrote: > Hello! > > The add_full() function currently has a lockdep_assert_held() requiring > that the kmem_cache_node structure's ->list_lock be held. However, > this lock is not acquired by add_full()'s caller deactivate_slab() > in the full-node case unless debugging is enabled. Because full nodes > are accessed only by debugging code, this state of affairs results in > lockdep false-positive splats like the following: > > [ 43.942868] WARNING: CPU: 0 PID: 698 at /home/paulmck/public_git/linux-rcu/mm/slub.c:1007 deactivate_slab+0x509/0x720() > [ 43.943016] Modules linked in: > [ 43.943016] CPU: 0 PID: 698 Comm: torture_onoff Not tainted 3.14.0-rc1+ #1 > [ 43.943016] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007 > [ 43.943016] 00000000000003ef ffff88001e3f5ba8 ffffffff818952ec 0000000000000046 > [ 43.943016] 0000000000000000 ffff88001e3f5be8 ffffffff81049517 ffffea0000784e00 > [ 43.943016] 0000000000000000 ffffea00007a9000 0000000000000002 0000000000000000 > [ 43.943016] Call Trace: > [ 43.943016] [<ffffffff818952ec>] dump_stack+0x46/0x58 > [ 43.943016] [<ffffffff81049517>] warn_slowpath_common+0x87/0xb0 > [ 43.943016] [<ffffffff81049555>] warn_slowpath_null+0x15/0x20 > [ 43.943016] [<ffffffff8116e679>] deactivate_slab+0x509/0x720 > [ 43.943016] [<ffffffff8116eebb>] ? slab_cpuup_callback+0x3b/0x100 > [ 43.943016] [<ffffffff8116ef52>] ? slab_cpuup_callback+0xd2/0x100 > [ 43.943016] [<ffffffff8116ef24>] slab_cpuup_callback+0xa4/0x100 > [ 43.943016] [<ffffffff818a4c14>] notifier_call_chain+0x54/0x110 > [ 43.943016] [<ffffffff81075b79>] __raw_notifier_call_chain+0x9/0x10 > [ 43.943016] [<ffffffff8104963b>] __cpu_notify+0x1b/0x30 > [ 43.943016] [<ffffffff81049720>] cpu_notify_nofail+0x10/0x20 > [ 43.943016] [<ffffffff8188cc5d>] _cpu_down+0x10d/0x2e0 > [ 43.943016] [<ffffffff8188ce60>] cpu_down+0x30/0x50 > [ 43.943016] [<ffffffff811205f3>] torture_onoff+0xd3/0x3c0 > [ 43.943016] [<ffffffff81120520>] ? torture_onoff_stats+0x90/0x90 > [ 43.943016] [<ffffffff810710df>] kthread+0xdf/0x100 > [ 43.943016] [<ffffffff818a09cb>] ? _raw_spin_unlock_irq+0x2b/0x40 > [ 43.943016] [<ffffffff81071000>] ? flush_kthread_worker+0x130/0x130 > [ 43.943016] [<ffffffff818a983c>] ret_from_fork+0x7c/0xb0 > [ 43.943016] [<ffffffff81071000>] ? flush_kthread_worker+0x130/0x130 > > This commit therefore does the lockdep check only if debuggging is > enabled, thus avoiding the false positives. > > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> This was discussed in http://marc.info/?t=139145791300002, what do you think about the patch in that thread instead? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>