From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: Re: Repeatable inet6_dump_fib crash in stock 4.12.0-rc4+ Date: Tue, 13 Jun 2017 20:27:20 -0600 Message-ID: <3230b360-528b-0ae0-8731-7906e57ee993@gmail.com> References: <1496795269.736.21.camel@edumazet-glaptop3.roam.corp.google.com> <1496809166.736.25.camel@edumazet-glaptop3.roam.corp.google.com> <94bcc041-6402-d0ce-b9cf-3b46aa622f34@candelatech.com> <7e0c97fa-cd6e-ed0f-bf99-0e4af40fbd2f@gmail.com> <1497043557.736.94.camel@edumazet-glaptop3.roam.corp.google.com> <9cb61ef0-37c0-8f35-bb5c-e3d8e63cbe2f@candelatech.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------DFC7C3978A65004608A000C6" Cc: Eric Dumazet , netdev To: Cong Wang , Ben Greear Return-path: Received: from mail-pf0-f170.google.com ([209.85.192.170]:33792 "EHLO mail-pf0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752854AbdFNC1Y (ORCPT ); Tue, 13 Jun 2017 22:27:24 -0400 Received: by mail-pf0-f170.google.com with SMTP id s66so8383441pfs.1 for ; Tue, 13 Jun 2017 19:27:24 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: This is a multi-part message in MIME format. --------------DFC7C3978A65004608A000C6 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit On 6/13/17 3:42 PM, Cong Wang wrote: > On Tue, Jun 13, 2017 at 1:16 PM, Ben Greear wrote: >> On 06/09/2017 02:25 PM, Eric Dumazet wrote: >>> >>> On Fri, 2017-06-09 at 07:27 -0600, David Ahern wrote: >>>> >>>> On 6/8/17 11:55 PM, Cong Wang wrote: >>>>> Apparently fn->parent is NULL here for some reason, but >>>>> I don't know if that is expected or not. If a simple NULL check >>>>> is not enough here, we have to trace why it is NULL. >>>> >>>> >>>> From my understanding, parent should not be null hence the attempts to >>>> fix access to table nodes under a lock. ie., figuring out why it is null >>>> here. >> >> >> If someone has more suggestions, I'll be happy to test. > > Can you enable RT6_TRACE() by changing RT6_DEBUG > from 2 to 3? We may collect some useful log with it. > > diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c > index d4bf2c6..1941595 100644 > --- a/net/ipv6/ip6_fib.c > +++ b/net/ipv6/ip6_fib.c > @@ -37,7 +37,7 @@ > #include > #include > > -#define RT6_DEBUG 2 > +#define RT6_DEBUG 3 > > #if RT6_DEBUG >= 3 > #define RT6_TRACE(x...) pr_debug(x) > Let's try a targeted debug patch. See attached --------------DFC7C3978A65004608A000C6 Content-Type: text/plain; charset=UTF-8; x-mac-type="0"; x-mac-creator="0"; name="fib6-walk-debug.patch" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="fib6-walk-debug.patch" ZGlmZiAtLWdpdCBhL25ldC9pcHY2L2lwNl9maWIuYyBiL25ldC9pcHY2L2lwNl9maWIuYwpp bmRleCBkZWVhOTAxNzQ2YzguLjM2N2YxMjg0ZjA1YiAxMDA2NDQKLS0tIGEvbmV0L2lwdjYv aXA2X2ZpYi5jCisrKyBiL25ldC9pcHY2L2lwNl9maWIuYwpAQCAtMTM5Niw2ICsxMzk2LDgg QEAgc3RhdGljIHN0cnVjdCBmaWI2X25vZGUgKmZpYjZfcmVwYWlyX3RyZWUoc3RydWN0IG5l dCAqbmV0LAogCQkJCQkJUlQ2X1RSQUNFKCJXICVwIGFkanVzdGVkIGJ5IGRlbG5vZGUgMiwg cz0lZFxuIiwgdywgdy0+c3RhdGUpOwogCQkJCQkJdy0+c3RhdGUgPSB3LT5zdGF0ZSA+PSBG V1NfQyA/IEZXU19VIDogRldTX0lOSVQ7CiAJCQkJCX0KKwkJCQkJaWYgKHctPnN0YXRlID09 IEZXU19VKQorCQkJCQkJcHJfd2FybigiZmliNl9yZXBhaXJfdHJlZTogVyAlcCBhZGp1c3Rl ZCBieSBkZWxub2RlIDIsIHN0YXRlIEZXU19VXG4iLCB3LCB3LT5zdGF0ZSk7CiAJCQkJfQog CQkJfQogCQl9CkBAIC0xNDQ3LDggKzE0NDksMTAgQEAgc3RhdGljIHZvaWQgZmliNl9kZWxf cm91dGUoc3RydWN0IGZpYjZfbm9kZSAqZm4sIHN0cnVjdCBydDZfaW5mbyAqKnJ0cCwKIAkJ aWYgKHctPnN0YXRlID09IEZXU19DICYmIHctPmxlYWYgPT0gcnQpIHsKIAkJCVJUNl9UUkFD RSgid2Fsa2VyICVwIGFkanVzdGVkIGJ5IGRlbHJvdXRlXG4iLCB3KTsKIAkJCXctPmxlYWYg PSBydC0+ZHN0LnJ0Nl9uZXh0OwotCQkJaWYgKCF3LT5sZWFmKQorCQkJaWYgKCF3LT5sZWFm KSB7CisJCQkJcHJfd2FybigiZmliNl9kZWxfcm91dGU6IHdhbGtlciAlcCBhZGp1c3RlZCBi eSBkZWxyb3V0ZSAtIHN0YXRlIEZXU19VXG4iLCB3KTsKIAkJCQl3LT5zdGF0ZSA9IEZXU19V OworCQkJfQogCQl9CiAJfQogCXJlYWRfdW5sb2NrKCZuZXQtPmlwdjYuZmliNl93YWxrZXJf bG9jayk7CkBAIC0xNTkxLDYgKzE1OTUsNyBAQCBzdGF0aWMgaW50IGZpYjZfd2Fsa19jb250 aW51ZShzdHJ1Y3QgZmliNl93YWxrZXIgKncpCiAJCQkJY29udGludWU7CiAJCQl9CiBza2lw OgorCQkJcHJfd2FybigiZmliNl93YWxrX2NvbnRpbnVlOiBzZXQgc3RhdGUgdG8gRldTX1Vc biIpOwogCQkJdy0+c3RhdGUgPSBGV1NfVTsKIAkJY2FzZSBGV1NfVToKIAkJCWlmIChmbiA9 PSB3LT5yb290KQo= --------------DFC7C3978A65004608A000C6--