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From: Borislav Petkov <bp@alien8.de>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>,
	Marco Elver <elver@google.com>,
	syzbot <syzbot+ce179bc99e64377c24bc@syzkaller.appspotmail.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Jiri Olsa <jolsa@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Ingo Molnar <mingo@redhat.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	the arch/x86 maintainers <x86@kernel.org>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	syzkaller <syzkaller@googlegroups.com>
Subject: Re: general protection fault in perf_misc_flags
Date: Wed, 30 Sep 2020 18:31:20 +0200	[thread overview]
Message-ID: <20200930163120.GJ6810@zn.tnic> (raw)
In-Reply-To: <CACT4Y+Zc7kD431Aed49U4R6cqzWGAWqEXevnheRHKQRQoEnh7w@mail.gmail.com>

On Wed, Sep 30, 2020 at 06:23:44PM +0200, Dmitry Vyukov wrote:
> Here is the answer:
> https://github.com/google/syzkaller/blob/master/tools/create-gce-image.sh#L189
> 
> # rodata=n: mark_rodata_ro becomes very slow with KASAN (lots of PGDs)
> 
> I have some vague memory that there was some debug double checking
> that pages are indeed read-only and that debug check was slow, but it
> was always executed without rodata=n.

Sounds like debug_checkwx() which is disabled by turning off
CONFIG_DEBUG_WX.

You could either disable it in your .configs or, provided there's even
such an option, disable KASAN checking around it until that one-time
boot test completes and then reenable KASAN.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  parent reply	other threads:[~2020-09-30 16:31 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-19  8:32 general protection fault in perf_misc_flags syzbot
2020-09-19 11:08 ` Borislav Petkov
2020-09-21  5:54   ` Dmitry Vyukov
2020-09-21  8:08     ` Dmitry Vyukov
2020-09-21 20:59       ` Nick Desaulniers
2020-09-21 22:13         ` Borislav Petkov
2020-09-22 18:56           ` Nick Desaulniers
2020-09-22 19:29             ` Borislav Petkov
2020-09-23  9:03             ` Borislav Petkov
2020-09-23  9:24               ` Dmitry Vyukov
2020-09-23 10:34                 ` Borislav Petkov
2020-09-23 15:20                   ` Dmitry Vyukov
2020-09-25 12:22                     ` Dmitry Vyukov
2020-09-26  0:32                       ` Nick Desaulniers
2020-09-26  6:46                         ` Dmitry Vyukov
2020-09-26 17:14                         ` Borislav Petkov
2020-09-26 11:21                     ` Borislav Petkov
2020-09-26 12:08                       ` Dmitry Vyukov
2020-09-22  5:15         ` Dmitry Vyukov
2020-09-22  5:16         ` Dmitry Vyukov
2020-09-27 14:57 ` Borislav Petkov
2020-09-28  5:18   ` Dmitry Vyukov
2020-09-28  6:06     ` Dmitry Vyukov
2020-09-28  8:38       ` Borislav Petkov
2020-09-28  8:40         ` Dmitry Vyukov
2020-09-28  8:54           ` Borislav Petkov
2020-09-28 10:33             ` Dmitry Vyukov
2020-09-28 20:23               ` Borislav Petkov
2020-09-29  8:33                 ` Borislav Petkov
2020-09-29 13:29                   ` Dmitry Vyukov
2020-09-30 16:17                     ` Borislav Petkov
2020-09-30 16:23                       ` Dmitry Vyukov
2020-09-30 16:29                         ` Dmitry Vyukov
2020-09-30 16:31                         ` Borislav Petkov [this message]
2020-10-01 10:23                           ` Dmitry Vyukov
2020-10-01 11:05                             ` Borislav Petkov
2020-09-28 20:51               ` Nick Desaulniers
2020-09-28 21:19                 ` Andy Lutomirski
2020-09-28  7:25     ` Marco Elver
2020-09-28 20:32     ` Nick Desaulniers
2020-09-29 13:27       ` Dmitry Vyukov

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