From: Pavel Skripkin <paskripkin@gmail.com>
To: Dongliang Mu <mudongliangabcd@gmail.com>
Cc: alex.aring@gmail.com, "David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-wpan@vger.kernel.org, netdev@vger.kernel.org,
stefan@datenfreihafen.org,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
syzbot+b80c9959009a9325cdff@syzkaller.appspotmail.com,
Dan Carpenter <dan.carpenter@oracle.com>,
Greg KH <gregkh@linuxfoundation.org>
Subject: Re: Suggestions on how to debug kernel crashes where printk and gdb both does not work
Date: Mon, 14 Jun 2021 17:25:12 +0300 [thread overview]
Message-ID: <20210614172512.799db10d@gmail.com> (raw)
In-Reply-To: <CAD-N9QV5_91A6n5QcrafmQRbqH_qzFRatno-6z0i7q-V9VnLzg@mail.gmail.com>
On Mon, 14 Jun 2021 22:19:10 +0800
Dongliang Mu <mudongliangabcd@gmail.com> wrote:
> On Mon, Jun 14, 2021 at 9:34 PM Pavel Skripkin <paskripkin@gmail.com>
> wrote:
> >
> > On Mon, 14 Jun 2021 21:22:43 +0800
> > Dongliang Mu <mudongliangabcd@gmail.com> wrote:
> >
> > > Dear kernel developers,
> > >
> > > I was trying to debug the crash - memory leak in hwsim_add_one [1]
> > > recently. However, I encountered a disgusting issue: my
> > > breakpoint and printk/pr_alert in the functions that will be
> > > surely executed do not work. The stack trace is in the following.
> > > I wrote this email to ask for some suggestions on how to debug
> > > such cases?
> > >
> > > Thanks very much. Looking forward to your reply.
> > >
> >
> > Hi, Dongliang!
> >
> > This bug is not similar to others on the dashboard. I spent some
> > time debugging it a week ago. The main problem here, that memory
> > allocation happens in the boot time:
> >
> > > [<ffffffff84359255>] kernel_init+0xc/0x1a7 init/main.c:1447
> >
>
> Oh, nice catch. No wonder why my debugging does not work. :(
>
> > and reproducer simply tries to
> > free this data. You can use ftrace to look at it. Smth like this:
> >
> > $ echo 'hwsim_*' > $TRACE_DIR/set_ftrace_filter
>
> Thanks for your suggestion.
>
> Do you have any conclusions about this case? If you have found out the
> root cause and start writing patches, I will turn my focus to other
> cases.
No, I had some busy days and I have nothing about this bug for now.
I've just traced the reproducer execution and that's all :)
I guess, some error handling paths are broken, but Im not sure
>
> BTW, I only found another possible memory leak after some manual code
> review [1]. However, it is not the root cause for this crash.
>
> [1] https://lkml.org/lkml/2021/6/10/1297
>
> >
> > would work.
> >
> >
> > With regards,
> > Pavel Skripkin
With regards,
Pavel Skripkin
next prev parent reply other threads:[~2021-06-14 14:25 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-14 13:22 Suggestions on how to debug kernel crashes where printk and gdb both does not work Dongliang Mu
2021-06-14 13:34 ` Pavel Skripkin
2021-06-14 14:19 ` Dongliang Mu
2021-06-14 14:25 ` Pavel Skripkin [this message]
2021-06-14 14:40 ` Dongliang Mu
2021-06-14 14:47 ` Pavel Skripkin
2021-06-14 15:04 ` Dongliang Mu
2021-06-14 20:30 ` Pavel Skripkin
2021-06-15 10:37 ` Dongliang Mu
2021-06-15 13:34 ` Pavel Skripkin
2021-06-16 2:02 ` Dongliang Mu
2021-06-16 2:11 ` Dongliang Mu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210614172512.799db10d@gmail.com \
--to=paskripkin@gmail.com \
--cc=alex.aring@gmail.com \
--cc=dan.carpenter@oracle.com \
--cc=davem@davemloft.net \
--cc=gregkh@linuxfoundation.org \
--cc=kuba@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-wpan@vger.kernel.org \
--cc=mudongliangabcd@gmail.com \
--cc=netdev@vger.kernel.org \
--cc=stefan@datenfreihafen.org \
--cc=syzbot+b80c9959009a9325cdff@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.