wireguard.lists.zx2c4.com archive mirror
 help / color / mirror / Atom feed
From: Dmitry Vyukov <dvyukov@google.com>
To: Randy Dunlap <rdunlap@infradead.org>
Cc: syzbot <syzbot+a70a6358abd2c3f9550f@syzkaller.appspotmail.com>,
	 Peter Zijlstra <peterz@infradead.org>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	 "Jason A. Donenfeld" <Jason@zx2c4.com>,
	David Miller <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	 LKML <linux-kernel@vger.kernel.org>,
	netdev <netdev@vger.kernel.org>,
	 syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	 WireGuard mailing list <wireguard@lists.zx2c4.com>
Subject: Re: [syzbot] BUG: MAX_LOCKDEP_KEYS too low! (2)
Date: Wed, 19 May 2021 22:09:35 +0200	[thread overview]
Message-ID: <CACT4Y+aEtYPAdrU7KkE303yDw__QiG7m1tWVJewV8C_Mt9=1qg@mail.gmail.com> (raw)
In-Reply-To: <c545268c-fe62-883c-4c46-974b3bb3cea1@infradead.org>

On Wed, May 19, 2021 at 9:58 PM Randy Dunlap <rdunlap@infradead.org> wrote:
>
> On 5/19/21 12:48 PM, Dmitry Vyukov wrote:
> > On Wed, May 19, 2021 at 7:35 PM syzbot
> > <syzbot+a70a6358abd2c3f9550f@syzkaller.appspotmail.com> wrote:
> >>
> >> Hello,
> >>
> >> syzbot found the following issue on:
> >>
> >> HEAD commit:    b81ac784 net: cdc_eem: fix URL to CDC EEM 1.0 spec
> >> git tree:       net
> >> console output: https://syzkaller.appspot.com/x/log.txt?x=15a257c3d00000
> >> kernel config:  https://syzkaller.appspot.com/x/.config?x=5b86a12e0d1933b5
> >> dashboard link: https://syzkaller.appspot.com/bug?extid=a70a6358abd2c3f9550f
> >>
> >> Unfortunately, I don't have any reproducer for this issue yet.
> >>
> >> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> >> Reported-by: syzbot+a70a6358abd2c3f9550f@syzkaller.appspotmail.com
> >>
> >> BUG: MAX_LOCKDEP_KEYS too low!
> >
>
> include/linux/lockdep.h
>
> #define MAX_LOCKDEP_KEYS_BITS           13
> #define MAX_LOCKDEP_KEYS                (1UL << MAX_LOCKDEP_KEYS_BITS)

Ouch, so it's not configurable yet :(
Unless, of course, we identify the offender that produced thousands of
lock classes in the log and fix it.


> Documentation/locking/lockdep-design.rst:
>
> Troubleshooting:
> ----------------
>
> The validator tracks a maximum of MAX_LOCKDEP_KEYS number of lock classes.
> Exceeding this number will trigger the following lockdep warning::
>
>         (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
>
> By default, MAX_LOCKDEP_KEYS is currently set to 8191, and typical
> desktop systems have less than 1,000 lock classes, so this warning
> normally results from lock-class leakage or failure to properly
> initialize locks.  These two problems are illustrated below:
>
> >
> > What config controls this? I don't see "MAX_LOCKDEP_KEYS too low" in
> > any of the config descriptions...
> > Here is what syzbot used:
> >
> > CONFIG_LOCKDEP=y
> > CONFIG_LOCKDEP_BITS=16
> > CONFIG_LOCKDEP_CHAINS_BITS=17
> > CONFIG_LOCKDEP_STACK_TRACE_BITS=20
> > CONFIG_LOCKDEP_STACK_TRACE_HASH_BITS=14
> > CONFIG_LOCKDEP_CIRCULAR_QUEUE_BITS=12
> >
> > We already bumped most of these.
> > The log contains dump of the lockdep debug files, is there any offender?
> >
> > Also looking at the log I noticed a memory safety bug in lockdep implementation:
>
> ...
>
> --
> ~Randy
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/c545268c-fe62-883c-4c46-974b3bb3cea1%40infradead.org.

  reply	other threads:[~2021-05-19 20:09 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-19 17:35 syzbot
2021-05-19 19:48 ` Dmitry Vyukov
2021-05-19 19:57   ` Randy Dunlap
2021-05-19 20:09     ` Dmitry Vyukov [this message]
2021-05-20  5:02       ` Tetsuo Handa
2021-05-21  7:04         ` Dmitry Vyukov

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='CACT4Y+aEtYPAdrU7KkE303yDw__QiG7m1tWVJewV8C_Mt9=1qg@mail.gmail.com' \
    --to=dvyukov@google.com \
    --cc=Jason@zx2c4.com \
    --cc=davem@davemloft.net \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=penguin-kernel@i-love.sakura.ne.jp \
    --cc=peterz@infradead.org \
    --cc=rdunlap@infradead.org \
    --cc=syzbot+a70a6358abd2c3f9550f@syzkaller.appspotmail.com \
    --cc=syzkaller-bugs@googlegroups.com \
    --cc=wireguard@lists.zx2c4.com \
    --subject='Re: [syzbot] BUG: MAX_LOCKDEP_KEYS too low'\!' (2)' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).