On Thu, Nov 2, 2017 at 12:06 PM, Florian Westphal [off-list ref] wrote:

Cong Wang [off-list ref] wrote:

quoted

quoted

CPU: 0 PID: 23859 Comm: syz-executor2 Not tainted 4.14.0-rc5+ #140
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4665
 __in_dev_get_rtnl include/linux/inetdevice.h:230 [inline]
 fib_dump_info+0x1136/0x13d0 net/ipv4/fib_semantics.c:1377
 inet_rtm_getroute+0xf97/0x2d70 net/ipv4/route.c:2785

This is introduced by:

commit 394f51abb3d04f33fb798f04b16ae6b0491ea4ec
Author: Florian Westphal [off-list ref]
Date:   Tue Aug 15 16:34:44 2017 +0200

    ipv4: route: set ipv4 RTM_GETROUTE to not use rtnl

    Signed-off-by: Florian Westphal [off-list ref]
    Signed-off-by: David S. Miller [off-list ref]

Looks like we need a wrapper for rcu_dereference_protected(dev->ip_ptr).

Yes, thats the alternative to
https://patchwork.ozlabs.org/patch/833401/

which switches to _rcu version.

Yeah, that works too.