On 10/25/2016 01:19 PM, Yotam Gigi wrote: > >> -----Original Message----- >> From: netdev-owner@xxxxxxxxxxxxxxx [mailto:netdev-owner@xxxxxxxxxxxxxxx] On >> Behalf Of Jakub Kicinski >> Sent: Monday, October 17, 2016 10:20 PM >> To: Andy Adamson <andros@xxxxxxxxxx>; Anna Schumaker >> <Anna.Schumaker@xxxxxxxxxx>; linux-nfs@xxxxxxxxxxxxxxx >> Cc: netdev@xxxxxxxxxxxxxxx; Trond Myklebust <Trond.Myklebust@xxxxxxxxxx> >> Subject: nfs NULL-dereferencing in net-next >> >> Hi! >> >> I'm hitting this reliably on net-next, HEAD at 3f3177bb680f >> ("fsl/fman: fix error return code in mac_probe()"). > > > I see the same thing. It happens constantly on some of my machines, making them > completely unusable. > > I bisected it and got to the commit: > > commit 04ea1b3e6d8ed4978bb608c1748530af3de8c274 > Author: Andy Adamson <andros@xxxxxxxxxx> > Date: Fri Sep 9 09:22:27 2016 -0400 > > NFS add xprt switch addrs test to match client > > Signed-off-by: Andy Adamson <andros@xxxxxxxxxx> > Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> Thanks for reporting on this everyone! Does this patch help? >From 96376ca1dd4077a1d341bdcb9cc86426ee3844f1 Mon Sep 17 00:00:00 2001 From: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> Date: Wed, 26 Oct 2016 10:33:31 -0400 Subject: [PATCH] SUNRPC: Fix suspicious RCU usage We need to hold the rcu_read_lock() when calling rcu_dereference(), otherwise we can't guarantee that the object being dereferenced still exists. Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> --- net/sunrpc/clnt.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 34dd7b2..62a4827 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -2753,14 +2753,18 @@ EXPORT_SYMBOL_GPL(rpc_cap_max_reconnect_timeout); void rpc_clnt_xprt_switch_put(struct rpc_clnt *clnt) { + rcu_read_lock(); xprt_switch_put(rcu_dereference(clnt->cl_xpi.xpi_xpswitch)); + rcu_read_unlock(); } EXPORT_SYMBOL_GPL(rpc_clnt_xprt_switch_put); void rpc_clnt_xprt_switch_add_xprt(struct rpc_clnt *clnt, struct rpc_xprt *xprt) { + rcu_read_lock(); rpc_xprt_switch_add_xprt(rcu_dereference(clnt->cl_xpi.xpi_xpswitch), xprt); + rcu_read_unlock(); } EXPORT_SYMBOL_GPL(rpc_clnt_xprt_switch_add_xprt); @@ -2770,9 +2774,8 @@ bool rpc_clnt_xprt_switch_has_addr(struct rpc_clnt *clnt, struct rpc_xprt_switch *xps; bool ret; - xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch); - rcu_read_lock(); + xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch); ret = rpc_xprt_switch_has_addr(xps, sap); rcu_read_unlock(); return ret; -- 2.10.1 > > >> >> [ 23.409633] BUG: unable to handle kernel NULL pointer dereference at >> 0000000000000172 >> [ 23.418716] IP: [<ffffffffc041776c>] rpc_clnt_xprt_switch_has_addr+0xc/0x40 >> [sunrpc] >> [ 23.427574] PGD 859020067 [ 23.430472] PUD 858f2d067 >> PMD 0 [ 23.434311] >> [ 23.436133] Oops: 0000 [#1] PREEMPT SMP >> [ 23.440506] Modules linked in: nfsv4 ip6table_filter ip6_tables iptable_filter >> ip_tables ebtable_nat ebtables x_tables intel_ri >> [ 23.505915] CPU: 1 PID: 1067 Comm: mount.nfs Not tainted 4.8.0-perf-13951- >> g3f3177bb680f #51 >> [ 23.515363] Hardware name: Dell Inc. PowerEdge T630/0W9WXC, BIOS 1.2.10 >> 03/10/2015 >> [ 23.523937] task: ffff983e9086ea00 task.stack: ffffac6c0a57c000 >> [ 23.530641] RIP: 0010:[<ffffffffc041776c>] [<ffffffffc041776c>] >> rpc_clnt_xprt_switch_has_addr+0xc/0x40 [sunrpc] >> [ 23.542229] RSP: 0018:ffffac6c0a57fb28 EFLAGS: 00010a97 >> [ 23.548255] RAX: 00000000c80214ac RBX: ffff983e97c7b000 RCX: ffff983e9b3bc180 >> [ 23.556320] RDX: 0000000000000001 RSI: ffff983e9928ed28 RDI: ffffffffffffffea >> [ 23.564386] RBP: ffffac6c0a57fb38 R08: ffff983e97090630 R09: ffff983e9928ed30 >> [ 23.572452] R10: ffffac6c0a57fba0 R11: 0000000000000010 R12: ffffac6c0a57fba0 >> [ 23.580517] R13: ffff983e9928ed28 R14: 0000000000000000 R15: ffff983e91360560 >> [ 23.588585] FS: 00007f4c348aa880(0000) GS:ffff983e9f240000(0000) >> knlGS:0000000000000000 >> [ 23.597742] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> [ 23.604251] CR2: 0000000000000172 CR3: 0000000850a5f000 CR4: >> 00000000001406e0 >> [ 23.612316] Stack: >> [ 23.614648] ffff983e97c7b000 ffffac6c0a57fba0 ffffac6c0a57fb90 ffffffffc04d38c3 >> [ 23.623331] ffff983e91360500 ffff983e9928ed30 ffffffffc0b9e560 >> ffff983e913605b8 >> [ 23.632016] ffff983e9882e800 ffff983e9882e800 ffffac6c0a57fc30 ffffac6c0a57fdb8 >> [ 23.640706] Call Trace: >> [ 23.643535] [<ffffffffc04d38c3>] nfs_get_client+0x123/0x340 [nfs] >> [ 23.650542] [<ffffffffc0b8f070>] nfs4_set_client+0x80/0xb0 [nfsv4] >> [ 23.657642] [<ffffffffc0b90305>] nfs4_create_server+0x115/0x2a0 [nfsv4] >> [ 23.665230] [<ffffffffc0b888ce>] nfs4_remote_mount+0x2e/0x60 [nfsv4] >> [ 23.672519] [<ffffffffba1e590a>] mount_fs+0x3a/0x160 >> [ 23.678254] [<ffffffffba201a5e>] ? alloc_vfsmnt+0x19e/0x230 >> [ 23.684669] [<ffffffffba201b57>] vfs_kern_mount+0x67/0x110 >> [ 23.690990] [<ffffffffc0b887f4>] nfs_do_root_mount+0x84/0xc0 [nfsv4] >> [ 23.698284] [<ffffffffc0b88b97>] nfs4_try_mount+0x37/0x50 [nfsv4] >> [ 23.705287] [<ffffffffc04dfbd1>] nfs_fs_mount+0x2d1/0xa70 [nfs] >> [ 23.712092] [<ffffffffba3a6228>] ? find_next_bit+0x18/0x20 >> [ 23.718413] [<ffffffffc04deac0>] ? nfs_remount+0x3c0/0x3c0 [nfs] >> [ 23.725316] [<ffffffffc04dedb0>] ? nfs_clone_super+0x130/0x130 [nfs] >> [ 23.732606] [<ffffffffba1e590a>] mount_fs+0x3a/0x160 >> [ 23.738340] [<ffffffffba201a5e>] ? alloc_vfsmnt+0x19e/0x230 >> [ 23.744755] [<ffffffffba201b57>] vfs_kern_mount+0x67/0x110 >> [ 23.751071] [<ffffffffba2041df>] do_mount+0x1bf/0xc70 >> [ 23.756904] [<ffffffffba203e9b>] ? copy_mount_options+0xbb/0x220 >> [ 23.763803] [<ffffffffba204fa3>] SyS_mount+0x83/0xd0 >> [ 23.769538] [<ffffffffba6f1ea4>] entry_SYSCALL_64_fastpath+0x17/0x98 >> [ 23.776817] Code: 01 00 48 8b 93 f8 04 00 00 44 89 e6 48 c7 c7 98 b2 43 c0 e8 9f 0d d4 >> f9 eb c0 0f 1f 44 00 00 0f 1f 44 00 00 >> [ 23.802909] RIP [<ffffffffc041776c>] rpc_clnt_xprt_switch_has_addr+0xc/0x40 >> [sunrpc] >> [ 23.811857] RSP <ffffac6c0a57fb28> >> [ 23.815839] CR2: 0000000000000172 >> [ 23.819629] ---[ end trace 9958eca92c9eeafe ]--- >> [ 23.827345] note: mount.nfs[1067] exited with preempt_count 1 > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
