Messages in this thread | | | Date | Fri, 28 Jul 2006 18:17:56 +0900 (JST) | Subject | Re: [mm-patch] bluetooth: use GFP_ATOMIC in *_sock_create's sk_alloc | From | Masatake YAMATO <> |
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> I think that the bluetooth-guard-bt_proto-with-rwlock.patch introduced the following > BUG: > [ 43.232000] BUG: sleeping function called from invalid context at mm/slab.c:2903 > [ 43.232000] in_atomic():1, irqs_disabled():0 > [ 43.232000] [<c0104114>] show_trace_log_lvl+0x197/0x1ba > [ 43.232000] [<c010415e>] show_trace+0x27/0x29 > [ 43.232000] [<c010426e>] dump_stack+0x26/0x28 > [ 43.232000] [<c011ad1c>] __might_sleep+0xa2/0xaa > [ 43.232000] [<c0173085>] __kmalloc+0x9c/0xb3 > [ 43.232000] [<c02f9295>] sk_alloc+0x1bc/0x1de > [ 43.232000] [<c036d689>] hci_sock_create+0x42/0x8a > [ 43.236000] [<c0366f40>] bt_sock_create+0xb5/0x154 > [ 43.236000] [<c02f69dc>] __sock_create+0x131/0x356 > [ 43.236000] [<c02f6c2f>] sock_create+0x2e/0x30 > [ 43.236000] [<c02f6c88>] sys_socket+0x27/0x53 > [ 43.240000] [<c02f7db5>] sys_socketcall+0xa9/0x277 > [ 43.240000] [<c0103131>] sysenter_past_esp+0x56/0x8d > [ 43.240000] [<b7f38410>] 0xb7f38410 > > > This patch makes sk_alloc GFP_ATOMIC, because we are holding the bt_proto_rwlock, for > the following functions: > - bnep_sock_create > - cmtp_sock_create > - hci_sock_create > - hidp_sock_create > - l2cap_sock_create > - rfcomm_sock_create > - sco_sock_create
There is very similar code in i net/socket.c(I guess some part of bluetooth/af_bluetooth.c is derived from net/socket.c):
static int __sock_create(int family, int type, int protocol, struct socket **res, int kern) { ... net_family_read_lock(); ... if ((err = net_families[family]->create(sock, protocol)) < 0) { sock->ops = NULL; goto out_module_put; } ... net_family_read_unlock(); return err; }
I can find GFP_KERNEL is used to allocate object in net_families[family]->create(sock, protocol). e.g.:
net/ipv4/af_inet.c: static int inet_create(struct socket *sock, int protocol) { ... sk = sk_alloc(PF_INET, GFP_KERNEL, answer_prot, 1); ... }
Tricks are in net_family_read_lock and net_family_read_unlock:
net/socket.c: static __inline__ void net_family_read_lock(void) { atomic_inc(&net_family_lockct); spin_unlock_wait(&net_family_lock); }
static __inline__ void net_family_read_unlock(void) { atomic_dec(&net_family_lockct); }
So there are two ways to avoid the bug: 1. As proposed by Frederik, use sk_alloc with GFP_ATOMIC or 2. use net_family_{read|writ}_{lock|unlock} in af_bluetooth.c.
I wonder which is better.
Masatake YAMATO - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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