From: Linus Torvalds <torvalds@linux-foundation.org>
To: Fengguang Wu <fengguang.wu@intel.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
Network Development <netdev@vger.kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
intel-wired-lan@lists.osuosl.org
Subject: Re: [vlan_device_event] BUG: unable to handle kernel paging request at 6b6b6ccf
Date: Wed, 8 Nov 2017 10:05:50 -0800 [thread overview]
Message-ID: <CA+55aFxohPiat5DpPqfxiJqvChKqq=giL-FMPbbVPkdcP49SEA@mail.gmail.com> (raw)
In-Reply-To: <20171108171230.ccf7lwutjysk26fc@wfg-t540p.sh.intel.com>
On Wed, Nov 8, 2017 at 9:12 AM, Fengguang Wu <fengguang.wu@intel.com> wrote:
>
> OK. Here is the original faddr2line output:
>
> $ ~/linux/scripts/faddr2line vmlinux vlan_device_event+0x7f5/0xa40
> vlan_device_event+0x7f5/0xa40:
> vlan_device_event at net/8021q/vlan.h:60
Hmm. Yes, that's not what I hoped for.
> I notice that this trace shows no additional inline files at all.
> Is it because I did some kconfig option wrong, so that inline info is
> lost? Eg.
>
> CONFIG_OPTIMIZE_INLINING=y (reading lib/Kconfig.debug, it looks better set to N)
> CONFIG_DEBUG_INFO_REDUCED=y
> CONFIG_DEBUG_INFO_SPLIT=y
Hmm. It might also be a compiler/linker issue. Debug info is sadly
often a second class citizen, because it's generally not something
that gets tested nearly as much as the actual _code_ that a compiler
generates.
So we've certainly had issues before with incomplete debug info.
That said, I'm not sure how well that CONFIG_DEBUG_INFO_SPLIT works,
I've only ever tested with
CONFIG_DEBUG_INFO=y
CONFIG_DEBUG_INFO_REDUCED=y
# CONFIG_DEBUG_INFO_SPLIT is not set
# CONFIG_DEBUG_INFO_DWARF4 is not set
which was the config that my scheduler example was generated from.
It might be an issue with the particular version of 'addr2line' too,
for all I know. The one I have is
GNU addr2line version 2.27-24.fc26
and who knows what else could influence it. I *thought* that as long
as you just had DEBUG_INFO enabled, it would automatically be ok, but
I was clearly wrong.
> [ 745.719623] BUG: unable to handle kernel paging request at 6b6b6f4f
> [ 745.732871] IP: vlan_device_event+0x7f5/0xa40:
> vlan_device_event at net/8021q/vlan.h:60
Ok, at least now there's no lost information, even if it doesn't have
that nice inlining information that I was hoping for.
Linus
next prev parent reply other threads:[~2017-11-08 18:05 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-07 10:21 [vlan_device_event] BUG: unable to handle kernel paging request at 6b6b6ccf Fengguang Wu
2017-11-07 16:25 ` Linus Torvalds
2017-11-07 16:46 ` Fengguang Wu
2017-11-08 9:48 ` Fengguang Wu
2017-11-08 16:20 ` Linus Torvalds
2017-11-08 17:12 ` Fengguang Wu
2017-11-08 17:18 ` Fengguang Wu
2017-11-08 18:05 ` Linus Torvalds [this message]
2017-11-08 18:36 ` Alexander Duyck
2017-11-09 3:12 ` Fengguang Wu
2017-11-09 4:09 ` Fengguang Wu
2017-11-09 7:22 ` Fengguang Wu
2017-11-09 6:34 ` Cong Wang
2017-11-09 6:55 ` Fengguang Wu
2017-11-09 7:43 ` Fengguang Wu
2017-11-09 15:51 ` Girish Moodalbail
2017-11-10 0:16 ` Cong Wang
2017-11-12 19:31 ` Linus Torvalds
2017-11-13 1:13 ` CONFIG_DEBUG_INFO_SPLIT impacts on faddr2line Fengguang Wu
2017-11-13 2:05 ` Zhang Rui
2017-11-13 2:22 ` Fengguang Wu
2017-11-13 18:52 ` Andi Kleen
2017-11-13 19:14 ` Linus Torvalds
2017-11-13 20:10 ` Andi Kleen
2017-11-13 20:14 ` H.J. Lu
2017-11-13 20:56 ` Linus Torvalds
2017-11-13 21:41 ` Andi Kleen
2017-11-13 21:57 ` Linus Torvalds
2017-11-13 23:51 ` Andi Kleen
2017-11-14 8:13 ` Fengguang Wu
2017-11-09 2:43 ` [vlan_device_event] BUG: unable to handle kernel paging request at 6b6b6ccf Fengguang Wu
2017-11-09 6:48 ` Fengguang Wu
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