Re: [PATCH] lockd: ensure we tear down any live sockets when socket creation fails during lockd_up

["J. Bruce Fields" <bfields@fieldses.org>]

On Fri, Mar 28, 2014 at 10:32:55AM +0400, Stanislav Kinsbursky wrote:
> 28.03.2014 07:37, Jeff Layton пишет:
> >On Thu, 27 Mar 2014 22:12:34 -0400
> >"J. Bruce Fields" <bfields@fieldses.org> wrote:
> >
> >>Thanks, applying.
> >>
> >>(Can you tell if this has always been there, or if it was introduced
> >>recently?  I guess it should go to stable, anyway....)
> >>
> >>--b.
> >>
> >
> >(cc'ing Stanislav so he's aware...)
> >
> 
> Looks reasonable.
> Thanks for involving me into discussion, Jeff.

Thanks for the review!

--b.

> 
> >Yeah, probably reasonable for stable...
> >
> >Looks like this bug crept in with 786185b5f8abefa. Prior to that we
> >called svc_shutdown_net from svc_destroy, which cleaned up the sockets
> >before the BUG_ON.
> >
> >FWIW, the Fedora bug report is here in case anyone is interested:
> >
> >     https://bugzilla.redhat.com/show_bug.cgi?id=1079700
> >
> >>On Tue, Mar 25, 2014 at 11:55:26AM -0700, Jeff Layton wrote:
> >>>We had a Fedora ABRT report with a stack trace like this:
> >>>
> >>>kernel BUG at net/sunrpc/svc.c:550!
> >>>invalid opcode: 0000 [#1] SMP
> >>>[...]
> >>>CPU: 2 PID: 913 Comm: rpc.nfsd Not tainted 3.13.6-200.fc20.x86_64 #1
> >>>Hardware name: Hewlett-Packard HP ProBook 4740s/1846, BIOS 68IRR
> >>>Ver. F.40 01/29/2013 task: ffff880146b00000 ti: ffff88003f9b8000
> >>>task.ti: ffff88003f9b8000 RIP: 0010:[<ffffffffa0305fa8>]
> >>>[<ffffffffa0305fa8>] svc_destroy+0x128/0x130 [sunrpc] RSP:
> >>>0018:ffff88003f9b9de0  EFLAGS: 00010206 RAX: ffff88003f829628 RBX:
> >>>ffff88003f829600 RCX: 00000000000041ee RDX: 0000000000000000 RSI:
> >>>0000000000000286 RDI: 0000000000000286 RBP: ffff88003f9b9de8 R08:
> >>>0000000000017360 R09: ffff88014fa97360 R10: ffffffff8114ce57 R11:
> >>>ffffea00051c9c00 R12: ffff88003f829600 R13: 00000000ffffff9e R14:
> >>>ffffffff81cc7cc0 R15: 0000000000000000 FS:  00007f4fde284840(0000)
> >>>GS:ffff88014fa80000(0000) knlGS:0000000000000000 CS:  0010 DS: 0000
> >>>ES: 0000 CR0: 0000000080050033 CR2: 00007f4fdf5192f8 CR3:
> >>>00000000a569a000 CR4: 00000000001407e0 Stack:
> >>>  ffff88003f792300 ffff88003f9b9e18 ffffffffa02de02a 0000000000000000
> >>>  ffffffff81cc7cc0 ffff88003f9cb000 0000000000000008 ffff88003f9b9e60
> >>>  ffffffffa033bb35 ffffffff8131c86c ffff88003f9cb000 ffff8800a5715008
> >>>Call Trace:
> >>>  [<ffffffffa02de02a>] lockd_up+0xaa/0x330 [lockd]
> >>>  [<ffffffffa033bb35>] nfsd_svc+0x1b5/0x2f0 [nfsd]
> >>>  [<ffffffff8131c86c>] ? simple_strtoull+0x2c/0x50
> >>>  [<ffffffffa033c630>] ? write_pool_threads+0x280/0x280 [nfsd]
> >>>  [<ffffffffa033c6bb>] write_threads+0x8b/0xf0 [nfsd]
> >>>  [<ffffffff8114efa4>] ? __get_free_pages+0x14/0x50
> >>>  [<ffffffff8114eff6>] ? get_zeroed_page+0x16/0x20
> >>>  [<ffffffff811dec51>] ? simple_transaction_get+0xb1/0xd0
> >>>  [<ffffffffa033c098>] nfsctl_transaction_write+0x48/0x80 [nfsd]
> >>>  [<ffffffff811b8b34>] vfs_write+0xb4/0x1f0
> >>>  [<ffffffff811c3f99>] ? putname+0x29/0x40
> >>>  [<ffffffff811b9569>] SyS_write+0x49/0xa0
> >>>  [<ffffffff810fc2a6>] ? __audit_syscall_exit+0x1f6/0x2a0
> >>>  [<ffffffff816962e9>] system_call_fastpath+0x16/0x1b
> >>>Code: 31 c0 e8 82 db 37 e1 e9 2a ff ff ff 48 8b 07 8b 57 14 48 c7
> >>>c7 d5 c6 31 a0 48 8b 70 20 31 c0 e8 65 db 37 e1 e9 f4 fe ff ff 0f
> >>>0b <0f> 0b 66 0f 1f 44 00 00 0f 1f 44 00 00 55 48 89 e5 41 56 41 55
> >>>RIP  [<ffffffffa0305fa8>] svc_destroy+0x128/0x130 [sunrpc] RSP
> >>><ffff88003f9b9de0>
> >>>
> >>>Evidently, we created some lockd sockets and then failed to create
> >>>others. make_socks then returned an error and we tried to tear down
> >>>the svc, but svc->sv_permsocks was not empty so we ended up
> >>>tripping over the BUG() in svc_destroy().
> >>>
> >>>Fix this by ensuring that we tear down any live sockets we created
> >>>when socket creation is going to return an error.
> >>>
> >>>Reported-by: Raphos <raphoszap@laposte.net>
> >>>Signed-off-by: Jeff Layton <jlayton@redhat.com>
> >>>---
> >>>  fs/lockd/svc.c | 1 +
> >>>  1 file changed, 1 insertion(+)
> >>>
> >>>diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
> >>>index 10d6c41aecad..6bf06a07f3e0 100644
> >>>--- a/fs/lockd/svc.c
> >>>+++ b/fs/lockd/svc.c
> >>>@@ -235,6 +235,7 @@ out_err:
> >>>  	if (warned++ == 0)
> >>>  		printk(KERN_WARNING
> >>>  			"lockd_up: makesock failed, error=%d\n",
> >>>err);
> >>>+	svc_shutdown_net(serv, net);
> >>>  	return err;
> >>>  }
> >>>
> >>>--
> >>>1.8.5.3
> >>>
> >
> >
> >
> 
> 
> -- 
> Best regards,
> Stanislav Kinsbursky