On Mon, Mar 13, 2023 at 7:15 AM Matthieu Baerts
<matthieu.baerts@xxxxxxxxxxxx> wrote:
>
> Hi Lorenzo,
>
> On 09/03/2023 13:25, Lorenzo Bianconi wrote:
> > Take into account tx/rx queues reconfiguration setting device
> > xdp_features flag. Moreover consider NETIF_F_GRO flag in order to enable
> > ndo_xdp_xmit callback.
> >
> > Fixes: 66c0e13ad236 ("drivers: net: turn on XDP features")
> > Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
>
> Thank you for the modification.
>
> Unfortunately, 'git bisect' just told me this modification is the origin
> of a new WARN when using veth in a netns:
>
>
> ###################### 8< ######################
>
> =============================
> WARNING: suspicious RCU usage
> 6.3.0-rc1-00144-g064d70527aaa #149 Not tainted
> -----------------------------
> drivers/net/veth.c:1265 suspicious rcu_dereference_check() usage!
>
> other info that might help us debug this:
>
Same observation here, I am releasing a syzbot report with a repro.
>
> rcu_scheduler_active = 2, debug_locks = 1
> 1 lock held by ip/135:
> #0: ffffffff8dc4b108 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg
> (net/core/rtnetlink.c:6172)
>
> stack backtrace:
> CPU: 1 PID: 135 Comm: ip Not tainted 6.3.0-rc1-00144-g064d70527aaa #149
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1
> 04/01/2014
> Call Trace:
> <TASK>
> dump_stack_lvl (lib/dump_stack.c:107)
> lockdep_rcu_suspicious (include/linux/context_tracking.h:152)
> veth_set_xdp_features (drivers/net/veth.c:1265 (discriminator 9))
> veth_newlink (drivers/net/veth.c:1892)
> ? veth_set_features (drivers/net/veth.c:1774)
> ? kasan_save_stack (mm/kasan/common.c:47)
> ? kasan_save_stack (mm/kasan/common.c:46)
> ? kasan_set_track (mm/kasan/common.c:52)
> ? alloc_netdev_mqs (include/linux/slab.h:737)
> ? rcu_read_lock_sched_held (kernel/rcu/update.c:125)
> ? trace_kmalloc (include/trace/events/kmem.h:54)
> ? __xdp_rxq_info_reg (net/core/xdp.c:188)
> ? alloc_netdev_mqs (net/core/dev.c:10657)
> ? rtnl_create_link (net/core/rtnetlink.c:3312)
> rtnl_newlink_create (net/core/rtnetlink.c:3440)
> ? rtnl_link_get_net_capable.constprop.0 (net/core/rtnetlink.c:3391)
> __rtnl_newlink (net/core/rtnetlink.c:3657)
> ? lock_downgrade (kernel/locking/lockdep.c:5321)
> ? rtnl_link_unregister (net/core/rtnetlink.c:3487)
> rtnl_newlink (net/core/rtnetlink.c:3671)
> rtnetlink_rcv_msg (net/core/rtnetlink.c:6174)
> ? rtnl_link_fill (net/core/rtnetlink.c:6070)
> ? mark_usage (kernel/locking/lockdep.c:4914)
> ? mark_usage (kernel/locking/lockdep.c:4914)
> netlink_rcv_skb (net/netlink/af_netlink.c:2574)
> ? rtnl_link_fill (net/core/rtnetlink.c:6070)
> ? netlink_ack (net/netlink/af_netlink.c:2551)
> ? lock_acquire (kernel/locking/lockdep.c:467)
> ? net_generic (include/linux/rcupdate.h:805)
> ? netlink_deliver_tap (include/linux/rcupdate.h:805)
> netlink_unicast (net/netlink/af_netlink.c:1340)
> ? netlink_attachskb (net/netlink/af_netlink.c:1350)
> netlink_sendmsg (net/netlink/af_netlink.c:1942)
> ? netlink_unicast (net/netlink/af_netlink.c:1861)
> ? netlink_unicast (net/netlink/af_netlink.c:1861)
> sock_sendmsg (net/socket.c:727)
> ____sys_sendmsg (net/socket.c:2501)
> ? kernel_sendmsg (net/socket.c:2448)
> ? __copy_msghdr (net/socket.c:2428)
> ___sys_sendmsg (net/socket.c:2557)
> ? mark_usage (kernel/locking/lockdep.c:4914)
> ? do_recvmmsg (net/socket.c:2544)
> ? lock_acquire (kernel/locking/lockdep.c:467)
> ? find_held_lock (kernel/locking/lockdep.c:5159)
> ? __lock_release (kernel/locking/lockdep.c:5345)
> ? __might_fault (mm/memory.c:5625)
> ? lock_downgrade (kernel/locking/lockdep.c:5321)
> ? __fget_light (include/linux/atomic/atomic-arch-fallback.h:227)
> __sys_sendmsg (include/linux/file.h:31)
> ? __sys_sendmsg_sock (net/socket.c:2572)
> ? rseq_get_rseq_cs (kernel/rseq.c:275)
> ? lockdep_hardirqs_on_prepare.part.0 (kernel/locking/lockdep.c:4263)
> do_syscall_64 (arch/x86/entry/common.c:50)
> entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
> RIP: 0033:0x7f0d1aadeb17
> Code: 0f 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b9 0f 1f 00 f3 0f 1e
> fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2e 00 00 00 0f 05 <48> 3d 00
> f0 ff ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 89 74 24 10
> All code
> ========
> 0: 0f 00 (bad)
> 2: f7 d8 neg %eax
> 4: 64 89 02 mov %eax,%fs:(%rdx)
> 7: 48 c7 c0 ff ff ff ff mov $0xffffffffffffffff,%rax
> e: eb b9 jmp 0xffffffffffffffc9
> 10: 0f 1f 00 nopl (%rax)
> 13: f3 0f 1e fa endbr64
> 17: 64 8b 04 25 18 00 00 mov %fs:0x18,%eax
> 1e: 00
> 1f: 85 c0 test %eax,%eax
> 21: 75 10 jne 0x33
> 23: b8 2e 00 00 00 mov $0x2e,%eax
> 28: 0f 05 syscall
> 2a:* 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax
> <-- trapping instruction
> 30: 77 51 ja 0x83
> 32: c3 ret
> 33: 48 83 ec 28 sub $0x28,%rsp
> 37: 89 54 24 1c mov %edx,0x1c(%rsp)
> 3b: 48 89 74 24 10 mov %rsi,0x10(%rsp)
>
> Code starting with the faulting instruction
> ===========================================
> 0: 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax
> 6: 77 51 ja 0x59
> 8: c3 ret
> 9: 48 83 ec 28 sub $0x28,%rsp
> d: 89 54 24 1c mov %edx,0x1c(%rsp)
> 11: 48 89 74 24 10 mov %rsi,0x10(%rsp)
> RSP: 002b:00007ffca3305d48 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 00000000640f2bb2 RCX: 00007f0d1aadeb17
> RDX: 0000000000000000 RSI: 00007ffca3305db0 RDI: 0000000000000003
> RBP: 0000000000000000 R08: 0000000000000001 R09: 00007ffca3304ae0
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
> R13: 00007ffca3305eb4 R14: 00007ffca3305e80 R15: 0000561e28bf5020
> </TASK>
> ip (135) used greatest stack depth: 24544 bytes left
>
> ###################### 8< ######################
>
>
> I can reproduce the issue on the "net" tree with just these 3 commands:
>
> # ip netns add ns1
> # ip netns add ns2
> # ip link add ns1eth1 netns ns1 type veth peer name ns2eth1 netns ns2
>
> Without this commit fccca038f300 ("veth: take into account device
> reconfiguration for xdp_features flag"), I don't have the issue.
>
> For more details about the issue detected by CIs validating our MPTCP
> tree, including kconfig and vmlinux if needed:
>
> https://github.com/multipath-tcp/mptcp_net-next/issues/372
>
>
> Do you mind looking at this regression please? :)
>
>
> On our side, we will revert this patch in our tree for the moment to
> unblock our CI jobs.
>
> Cheers,
> Matt
> --
> Tessares | Belgium | Hybrid Access Solutions
> www.tessares.net
