Guillaume Nault 58a89ecaca ppp: fix lockdep splat in ppp_dev_uninit() ... ppp_dev_uninit() locks all_ppp_mutex while under rtnl mutex protection. ppp_create_interface() must then lock these mutexes in that same order to avoid possible deadlock. [ 120.880011] ====================================================== [ 120.880011] [ INFO: possible circular locking dependency detected ] [ 120.880011] 4.2.0 #1 Not tainted [ 120.880011] ------------------------------------------------------- [ 120.880011] ppp-apitest/15827 is trying to acquire lock: [ 120.880011] (&pn->all_ppp_mutex){+.+.+.}, at: [<ffffffffa0145f56>] ppp_dev_uninit+0x64/0xb0 [ppp_generic] [ 120.880011] [ 120.880011] but task is already holding lock: [ 120.880011] (rtnl_mutex){+.+.+.}, at: [<ffffffff812e4255>] rtnl_lock+0x12/0x14 [ 120.880011] [ 120.880011] which lock already depends on the new lock. [ 120.880011] [ 120.880011] [ 120.880011] the existing dependency chain (in reverse order) is: [ 120.880011] [ 120.880011] -> #1 (rtnl_mutex){+.+.+.}: [ 120.880011] [<ffffffff81073a6f>] lock_acquire+0xcf/0x10e [ 120.880011] [<ffffffff813ab18a>] mutex_lock_nested+0x56/0x341 [ 120.880011] [<ffffffff812e4255>] rtnl_lock+0x12/0x14 [ 120.880011] [<ffffffff812d9d94>] register_netdev+0x11/0x27 [ 120.880011] [<ffffffffa0147b17>] ppp_ioctl+0x289/0xc98 [ppp_generic] [ 120.880011] [<ffffffff8113b367>] do_vfs_ioctl+0x4ea/0x532 [ 120.880011] [<ffffffff8113b3fd>] SyS_ioctl+0x4e/0x7d [ 120.880011] [<ffffffff813ad7d7>] entry_SYSCALL_64_fastpath+0x12/0x6f [ 120.880011] [ 120.880011] -> #0 (&pn->all_ppp_mutex){+.+.+.}: [ 120.880011] [<ffffffff8107334e>] __lock_acquire+0xb07/0xe76 [ 120.880011] [<ffffffff81073a6f>] lock_acquire+0xcf/0x10e [ 120.880011] [<ffffffff813ab18a>] mutex_lock_nested+0x56/0x341 [ 120.880011] [<ffffffffa0145f56>] ppp_dev_uninit+0x64/0xb0 [ppp_generic] [ 120.880011] [<ffffffff812d5263>] rollback_registered_many+0x19e/0x252 [ 120.880011] [<ffffffff812d5381>] rollback_registered+0x29/0x38 [ 120.880011] [<ffffffff812d53fa>] unregister_netdevice_queue+0x6a/0x77 [ 120.880011] [<ffffffffa0146a94>] ppp_release+0x42/0x79 [ppp_generic] [ 120.880011] [<ffffffff8112d9f6>] __fput+0xec/0x192 [ 120.880011] [<ffffffff8112dacc>] ____fput+0x9/0xb [ 120.880011] [<ffffffff8105447a>] task_work_run+0x66/0x80 [ 120.880011] [<ffffffff81001801>] prepare_exit_to_usermode+0x8c/0xa7 [ 120.880011] [<ffffffff81001900>] syscall_return_slowpath+0xe4/0x104 [ 120.880011] [<ffffffff813ad931>] int_ret_from_sys_call+0x25/0x9f [ 120.880011] [ 120.880011] other info that might help us debug this: [ 120.880011] [ 120.880011] Possible unsafe locking scenario: [ 120.880011] [ 120.880011] CPU0 CPU1 [ 120.880011] ---- ---- [ 120.880011] lock(rtnl_mutex); [ 120.880011] lock(&pn->all_ppp_mutex); [ 120.880011] lock(rtnl_mutex); [ 120.880011] lock(&pn->all_ppp_mutex); [ 120.880011] [ 120.880011] *** DEADLOCK *** Fixes: 8cb775bc0a ("ppp: fix device unregistration upon netns deletion") Reported-by: Sedat Dilek <sedat.dilek@gmail.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net>		2015-09-25 12:38:11 -07:00
..
bsd_comp.c
Kconfig	tty/serial patches for 3.9-rc1	2013-02-21 13:41:04 -08:00
Makefile
ppp_async.c	tty: Fix recursive deadlock in tty_perform_flush()	2013-03-18 16:52:24 -07:00
ppp_deflate.c	ppp: deflate: never return len larger than output buffer	2015-01-29 14:50:01 -08:00
ppp_generic.c	ppp: fix lockdep splat in ppp_dev_uninit()	2015-09-25 12:38:11 -07:00
ppp_mppe.c	ppp: mppe: discard late packet in stateless mode	2015-04-26 23:25:13 -04:00
ppp_mppe.h
ppp_synctty.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next	2013-05-01 14:08:52 -07:00
pppoe.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2015-05-13 14:31:43 -04:00
pppox.c	net: Pass kern from net_proto_family.create to sk_alloc	2015-05-11 10:50:17 -04:00
pptp.c	netfilter: Remove spurios included of netfilter.h	2015-06-18 21:14:32 +02:00