On 05/26/15 08:57, Nicholas A. Bellinger wrote:
> @@ -625,6 +626,7 @@ int core_dev_add_initiator_node_lun_acl(
> u32 lun_access)
> {
> struct se_node_acl *nacl = lacl->se_lun_nacl;
> + struct se_device *dev = lockless_dereference(lun->lun_se_dev);
>
> if (!nacl)
> return -EINVAL;
An attempt to run this code on a system with RCU debugging enabled
resulted in the following complaint:
===============================
[ INFO: suspicious RCU usage. ]
4.1.0-rc1-lio-dbg+ #1 Not tainted
-------------------------------
drivers/target/target_core_device.c:617 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 1
2 locks held by ln/1497:
#0: (sb_writers#11){.+.+.+}, at: [<ffffffff811d9ca4>] mnt_want_write+0x24/0x50
#1: (&sb->s_type->i_mutex_key#14/1){+.+.+.}, at: [<ffffffff811c4cdd>] filename_create+0xad/0x1a0
stack backtrace:
CPU: 0 PID: 1497 Comm: ln Not tainted 4.1.0-rc1-lio-dbg+ #1
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
0000000000000001 ffff88005955bd68 ffffffff814fa346 0000000000000011
ffff880058bf1270 ffff88005955bd98 ffffffff810ab235 ffff880050db9a68
ffff880058ae2e68 0000000000000002 ffff880058ae4120 ffff88005955be08
Call Trace:
[<ffffffff814fa346>] dump_stack+0x4f/0x7b
[<ffffffff810ab235>] lockdep_rcu_suspicious+0xd5/0x110
[<ffffffffa04324bc>] core_dev_add_initiator_node_lun_acl+0xec/0x190 [target_core_mod]
[<ffffffff8108f871>] ? get_parent_ip+0x11/0x50
[<ffffffffa04346f9>] target_fabric_mappedlun_link+0x129/0x240 [target_core_mod]
[<ffffffffa043466c>] ? target_fabric_mappedlun_link+0x9c/0x240 [target_core_mod]
[<ffffffffa035824d>] configfs_symlink+0x13d/0x360 [configfs]
[<ffffffff811be8c8>] vfs_symlink+0x58/0xb0
[<ffffffff811c75c5>] SyS_symlink+0x65/0xc0
[<ffffffff81502eb2>] system_call_fastpath+0x16/0x7a
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