On Wed, Nov 27, 2013 at 12:07:51PM +0400, Stanislav Kinsbursky wrote:
> 27.11.2013 11:54, Weng Meiling пишет:
> >
> >Hi guys,
> >
> >When I try to test NFS in different network namespace with stable-3.4,
> >I trigger a kernel panic. When NFSd was started in one non init_net network
> >namespace, and stopped in another one. This will trigger kernel panic, because
> >RPCBIND client is stored per net, and will be NULL on NFSd shutdown.
> >
> >The detail steps are:
> >
> >#ip netns add test
> >#ip netns exec test service nfsserver start
> >#service nfsserver stop
> >
> >The main call trace:
> >
> >[ 293.358078] BUG: unable to handle kernel NULL pointer dereference at 0000000000000060
> >[ 293.358089] IP: [<ffffffffa0446150>] call_start+0x10/0x30 [sunrpc]
> >
> >[ 293.358215] Pid: 5323, comm: nfsd Not tainted 3.4.69-default-stable+
> >
> >[ 293.358321] Call Trace:
> >[ 293.358336] [<ffffffffa044f401>] __rpc_execute+0x91/0x160 [sunrpc]
> >[ 293.358351] [<ffffffffa044f541>] rpc_execute+0x71/0x80 [sunrpc]
> >[ 293.358362] [<ffffffffa04479a9>] rpc_run_task+0x89/0xa0 [sunrpc]
> >[ 293.358374] [<ffffffffa0447abd>] rpc_call_sync+0x3d/0x70 [sunrpc]
> >[ 293.358390] [<ffffffffa0457bc6>] rpcb_register+0xa6/0xd0 [sunrpc]
> >[ 293.358406] [<ffffffffa0452345>] svc_unregister+0x95/0xf0 [sunrpc]
> >[ 293.358418] [<ffffffffa04ab8a0>] ? nfsd_last_thread+0x50/0x50 [nfsd]
> >[ 293.358433] [<ffffffffa04523b1>] svc_rpcb_cleanup+0x11/0x20 [sunrpc]
> >[ 293.358442] [<ffffffffa04ab877>] nfsd_last_thread+0x27/0x50 [nfsd]
> >[ 293.358457] [<ffffffffa0452280>] svc_shutdown_net+0x30/0x40 [sunrpc]
> >[ 293.358466] [<ffffffffa04ab9ed>] nfsd+0x14d/0x1a0 [nfsd]
> >[ 293.358475] [<ffffffffa04ab8a0>] ? nfsd_last_thread+0x50/0x50 [nfsd]
> >[ 293.358487] [<ffffffff8106459e>] kthread+0x9e/0xb0
> >[ 293.358496] [<ffffffff81465014>] kernel_thread_helper+0x4/0x10
> >[ 293.358503] [<ffffffff81064500>] ? kthread_freezable_should_stop+0x70/0x70
> >[ 293.358509] [<ffffffff81465010>] ? gs_change+0x13/0x13
> >
> >Walk through the code, this problem also exists in stable-3.5 to stable-3.7.
> >Stanislav Kinsbursky had committed a fixed patch for 3.8:
> >commit f7fb86c6e639360ad9c253cec534819ef928a674 (nfsd: use "init_net" for portmapper).
> >This patch is suitable for stable-3.4, but it causes another bug, When starting NFSd
> >in a non init_net network namespace will trigger kernel panic. Because RPCBIND client
> >will be NULL when register RPC service with the local portmapper in svc_addsock(). This
> >new bug also exists in 3.8, but disappears after patch commit 11f779421a39b86da8a523d97e5fd3477878d44f
> >("containerize NFSd filesystem") in 3.9.
> >
> >The detail steps are:
> >
> >#ip netns add test
> >#ip netns exec test service nfsserver start
> >
> >The main call trace:
> >
> >[ 136.877527] BUG: unable to handle kernel NULL pointer dereference at 0000000000000060
> >[ 136.877538] IP: [<ffffffffa0451150>] call_start+0x10/0x30 [sunrpc]
> >
> >[ 136.877664] Pid: 4854, comm: rpc.nfsd Not tainted 3.4.69-default-stable-nfs-test+
> >
> >[ 136.877769] Call Trace:
> >[ 136.877785] [<ffffffffa045a401>] __rpc_execute+0x91/0x160 [sunrpc]
> >[ 136.877799] [<ffffffffa045a541>] rpc_execute+0x71/0x80 [sunrpc]
> >[ 136.877811] [<ffffffffa04529a9>] rpc_run_task+0x89/0xa0 [sunrpc]
> >[ 136.877822] [<ffffffffa0452abd>] rpc_call_sync+0x3d/0x70 [sunrpc]
> >[ 136.877839] [<ffffffffa0462bc6>] rpcb_register+0xa6/0xd0 [sunrpc]
> >[ 136.877854] [<ffffffffa045ca9e>] __svc_register+0x1ae/0x1c0 [sunrpc]
> >[ 136.877870] [<ffffffffa045cb3f>] svc_register+0x8f/0xc0 [sunrpc]
> >[ 136.877882] [<ffffffff8114d855>] ? kmem_cache_alloc_trace+0xc5/0x1e0
> >[ 136.877897] [<ffffffffa045ec38>] svc_setup_socket+0x1a8/0x2c0 [sunrpc]
> >[ 136.877907] [<ffffffff81009546>] ? read_tsc+0x16/0x40
> >[ 136.877922] [<ffffffffa045f9b8>] svc_addsock+0x118/0x1c0 [sunrpc]
> >[ 136.877930] [<ffffffff8108f225>] ? do_gettimeofday+0x15/0x50
> >[ 136.877941] [<ffffffffa04aa69c>] ? nfsd_create_serv+0xdc/0x150 [nfsd]
> >[ 136.877951] [<ffffffffa04abdce>] __write_ports+0x1fe/0x230 [nfsd]
> >[ 136.877961] [<ffffffffa04abe37>] write_ports+0x37/0x60 [nfsd]
> >[ 136.877970] [<ffffffffa04abe00>] ? __write_ports+0x230/0x230 [nfsd]
> >[ 136.877979] [<ffffffffa04aadd2>] nfsctl_transaction_write+0x72/0x90 [nfsd]
> >[ 136.877987] [<ffffffff8115b4ab>] vfs_write+0xcb/0x130
> >[ 136.877992] [<ffffffff8115b600>] sys_write+0x50/0x90
> >[ 136.878000] [<ffffffff81463cb9>] system_call_fastpath+0x16/0x1b
> >
> >
> >Here is a way to resolve the problem:
> >Maybe we can backport the following patches from 3.8 to cleanup init_net reference:
> >
> >---
> >
> >Stanislav Kinsbursky (7):
> > nfsd: use "init_net" for portmapper commit f7fb86c6e639360ad9c253cec534819ef928a674
> > nfsd: pass net to nfsd_init_socks() commit db6e182c17cb1a7069f7f8924721ce58ac05d9a3
> > nfsd: pass net to nfsd_startup() and nfsd_shutdown() commit db42d1a76a8dfcaba7a2dc9c591fa4e231db22b3
> > nfsd: pass net to nfsd_create_serv() commit 6777436b0f072fb20a025a73e9b67a35ad8a5451
> > nfsd: pass net to nfsd_svc() commit d41a9417cd89a69f58a26935034b4264a2d882d6
> > nfsd: pass net to nfsd_set_nrthreads() commit 3938a0d5eb5effcc89c6909741403f4e6a37252d
> > nfsd: pass net to __write_ports() and down commit 081603520b25f7b35ef63a363376a17c36ef74ed
> >
> >
> > fs/nfsd/nfsctl.c | 27 +++++++++++++++------------
> > fs/nfsd/nfsd.h | 6 +++---
> > fs/nfsd/nfssvc.c | 35 ++++++++++++++---------------------
> > 3 files changed, 32 insertions(+), 36 deletions(-)
> >
> >Stanislav Kinsbursky:
> > nfsd: pass proper net to nfsd_destroy() from NFSd kthreads commit 88c47666171989ed4c5b1a5687df09511e8c5e35
> >
> > fs/nfsd/nfssvc.c | 4 +++-
> > 1 files changed, 3 insertions(+), 1 deletions(-)
> >
> >and then just a simple patch which uses the current->nsproxy->net_ns to repalce the
> >init_net to make NFSd keep using a consistent network namespace all the time can
> >resolve the problem. Maybe this is not optimal, what do you think about this problem?
> >
>
> Great investigation! Thanks.
> I think it's up to Bruce (cc'd) what is better: backport or simple fix, which just forbids
> NFSd start in non-init network namespace for kernels, prior to 3.9.
It seems rude to turn off a feature in a stable series, so backports are
probably better if we need to fix this. But somebody would need to test
the backports.
Weng Meiling, if you want this fixed on a stable branch:
- confirm that those patches fix the problem.
- send the resulting patches to stable@xxxxxxxxxxxxxxx with
cc:'s to at least Stanislav and me and
linux-nfs@xxxxxxxxxxxxxxx
and I can ack them.
--b.
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