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From: peterz@infradead.org
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	syzkaller <syzkaller@googlegroups.com>
Subject: Re: [PATCH v2] lockdep: Allow tuning tracing capacity constants.
Date: Wed, 16 Sep 2020 13:50:57 +0200	[thread overview]
Message-ID: <20200916115057.GO2674@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CACT4Y+bjPr=64Lq1-ARD6T=K9LmC_Aor4BRXPcZVtUU8vF0oGg@mail.gmail.com>

On Wed, Sep 16, 2020 at 01:28:19PM +0200, Dmitry Vyukov wrote:
> On Fri, Sep 4, 2020 at 6:05 PM Tetsuo Handa
> <penguin-kernel@i-love.sakura.ne.jp> wrote:
> >
> > Hello. Can we apply this patch?
> >
> > This patch addresses top crashers for syzbot, and applying this patch
> > will help utilizing syzbot's resource for finding other bugs.
> 
> Acked-by: Dmitry Vyukov <dvyukov@google.com>
> 
> Peter, do you still have concerns with this?

Yeah, I still hate it with a passion; it discourages thinking. A bad
annotation that blows up the lockdep storage, no worries, we'll just
increase this :/

IIRC the issue with syzbot is that the current sysfs annotation is
pretty terrible and generates a gazillion classes, and syzbot likes
poking at /sys a lot and thus floods the system.

I don't know enough about sysfs to suggest an alternative, and haven't
exactly had spare time to look into it either :/

Examples of bad annotations is getting every CPU a separate class, that
leads to nr_cpus! chains if CPUs arbitrarily nest (nr_cpus^2 if there's
only a single nesting level).

  reply	other threads:[~2020-09-16 20:24 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-25  1:30 [PATCH] lockdep: Introduce CONFIG_LOCKDEP_LARGE Tetsuo Handa
2020-07-25  4:48 ` Dmitry Vyukov
2020-07-25  5:23   ` Tetsuo Handa
2020-08-04  2:36     ` Tetsuo Handa
2020-08-18  9:57       ` Dmitry Vyukov
2020-08-18 11:07         ` Tetsuo Handa
2020-08-18 12:02           ` Dmitry Vyukov
2020-08-18 12:59             ` Tetsuo Handa
2020-08-27 15:20 ` [PATCH v2] lockdep: Allow tuning tracing capacity constants Tetsuo Handa
2020-09-04 16:05   ` Tetsuo Handa
2020-09-16 11:28     ` Dmitry Vyukov
2020-09-16 11:50       ` peterz [this message]
2020-09-16 12:14         ` Dmitry Vyukov
2020-09-28  0:24           ` Tetsuo Handa
2020-09-28  5:12             ` Dmitry Vyukov
2020-10-10 12:58   ` [PATCH v3] " Tetsuo Handa
2020-10-18 13:02     ` Tetsuo Handa
2020-11-18 13:57       ` Tetsuo Handa
2020-11-18 14:23         ` Peter Zijlstra
2020-11-18 14:30           ` Tetsuo Handa
2020-11-18 15:10             ` Peter Zijlstra
2020-11-18 15:31               ` Tetsuo Handa
2020-11-19 12:33                 ` Dmitry Vyukov
2020-11-19 12:43                   ` Dmitry Vyukov
2020-11-19 12:49                     ` Dmitry Vyukov
2020-11-19 13:06                       ` Dmitry Vyukov
2020-11-19 13:45                         ` Tetsuo Handa
2020-11-19 14:05                           ` Dmitry Vyukov
     [not found]                             ` <CACT4Y+aNJmuhk0KicX4FzKW6PhawFBgvrC2gSJcWwUkR8VSSmg@mail.gmail.com>
2020-11-19 14:36                               ` Dmitry Vyukov
2020-11-19 18:08                                 ` Dmitry Vyukov
2020-11-20  9:22                                   ` Dmitry Vyukov
2020-11-20  9:27                                     ` Dmitry Vyukov
2020-11-22  1:56                                       ` Tetsuo Handa
2020-11-27  9:00                                         ` Dmitry Vyukov
2020-12-03 13:47                                           ` Tetsuo Handa
2020-12-04 14:35                                             ` Tetsuo Handa
2020-11-19 14:57                               ` Tetsuo Handa
2021-01-01  8:09     ` [PATCH v4] " Tetsuo Handa

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