On Wed, Jan 22, 2020 at 10:38 PM Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote: > > > > On 1/22/20 1:01 PM, syzbot wrote: > > syzbot has bisected this bug to: > > > > commit 58956317c8de52009d1a38a721474c24aef74fe7 > > Author: David Ahern <dsahern@xxxxxxxxx> > > Date: Fri Dec 7 20:24:57 2018 +0000 > > > > neighbor: Improve garbage collection > > > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=124a5985e00000 > > start commit: d0f41851 net, ip_tunnel: fix namespaces move > > git tree: net > > final crash: https://syzkaller.appspot.com/x/report.txt?x=114a5985e00000 > > console output: https://syzkaller.appspot.com/x/log.txt?x=164a5985e00000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=d9290aeb7e6cf1c4 > > dashboard link: https://syzkaller.appspot.com/bug?extid=8ce4113dadc4789fac74 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11f99369e00000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13d85601e00000 > > > > Reported-by: syzbot+8ce4113dadc4789fac74@xxxxxxxxxxxxxxxxxxxxxxxxx > > Fixes: 58956317c8de ("neighbor: Improve garbage collection") > > > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > > > > bisection looks bogus... > > It would be nice to have alternative helpers to conveniently replace some WARN_ON/WARN_ONCE/... > and not having to hand-code stuff like : > > diff --git a/net/core/filter.c b/net/core/filter.c > index 538f6a735a19f017df8e10149cb578107ddc8cbb..633988f7c81b3b4f015d827ccb485e8b227ad20b 100644 > --- a/net/core/filter.c > +++ b/net/core/filter.c > @@ -6913,11 +6913,15 @@ static bool xdp_is_valid_access(int off, int size, > > void bpf_warn_invalid_xdp_action(u32 act) > { > + static bool __section(.data.once) warned; > const u32 act_max = XDP_REDIRECT; > > - WARN_ONCE(1, "%s XDP return value %u, expect packet loss!\n", > - act > act_max ? "Illegal" : "Driver unsupported", > - act); > + if (!warned) { > + warned = true; > + pr_err("%s XDP return value %u, expect packet loss!\n", > + act > act_max ? "Illegal" : "Driver unsupported", act); > + dump_stack(); > + } > } > EXPORT_SYMBOL_GPL(bpf_warn_invalid_xdp_action); If a single caller of this function would be enough (or maybe grand caller with a macro), then we could use pr_err_once/ratelimited and print 1 line with error and caller function.
