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From: "Paul E. McKenney" <paulmck@kernel.org>
To: Qian Cai <cai@lca.pw>
Cc: Marco Elver <elver@google.com>,
	LKMM Maintainers -- Akira Yokosawa <akiyks@gmail.com>,
	Alan Stern <stern@rowland.harvard.edu>,
	Alexander Potapenko <glider@google.com>,
	Andrea Parri <parri.andrea@gmail.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	Andy Lutomirski <luto@kernel.org>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Arnd Bergmann <arnd@arndb.de>, Boqun Feng <boqun.feng@gmail.com>,
	Borislav Petkov <bp@alien8.de>, Daniel Axtens <dja@axtens.net>,
	Daniel Lustig <dlustig@nvidia.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	David Howells <dhowells@redhat.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	Jade Alglave <j.alglave@ucl.ac.uk>,
	Joel Fernandes <joel@joelfernandes.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Luc Maranget <luc.maranget@inria.fr>,
	Mark Rutland <Mark.Rutland@arm.com>,
	Nicholas Piggin <npiggin@gmail.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Will Deacon <will@kernel.org>, Eric Dumazet <edumazet@google.com>,
	kasan-dev <kasan-dev@googlegroups.com>,
	linux-arch <linux-arch@vger.kernel.org>,
	"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	linux-efi@vger.kernel.org,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
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	the arch/x86 maintainers <x86@kernel.org>
Subject: Re: [PATCH v4 01/10] kcsan: Add Kernel Concurrency Sanitizer infrastructure
Date: Tue, 14 Jan 2020 13:34:05 -0800	[thread overview]
Message-ID: <20200114213405.GX2935@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <F185919B-2D86-43B6-9BEC-D14D72871A58@lca.pw>

On Tue, Jan 14, 2020 at 03:30:53PM -0500, Qian Cai wrote:
> 
> 
> > On Jan 14, 2020, at 2:22 PM, Paul E. McKenney <paulmck@kernel.org> wrote:
> > 
> > Just so I understand...  Does this problem happen even in CONFIG_KCSAN=n
> > kernels?
> 
> No.

Whew!!!  ;-)

> > I have been running extensive CONFIG_KSCAN=y rcutorture tests for quite
> > awhile now, so even if this only happens for CONFIG_KSCAN=y, it is not
> > like it affects everyone.
> > 
> > Yes, it should be fixed, and Marco does have a patch on the way.
> 
> The concern is really about setting KSCAN=y in a distro debug kernel where it has other debug options. I’ll try to dig into more of those issues in the next few days.

Understood.  But there are likely to be other issues with KCSAN, given how
new it is.  Yes, yes, I certainly would like to believe that the patches
we currently know about will make KCSAN perfect for distros, I have way
too much grey hair (and too little hair as well!) to really beleive that.

As an alternative, once the patches needed for your tests to pass
reach mainline, you could announce that KCSAN was ready to be enabled
in distros.

Though I confess that I don't know how that works.  Is there a separate
testing kernel binary provided by the distros in question?

							Thanx, Paul

WARNING: multiple messages have this Message-ID (diff)
From: "Paul E. McKenney" <paulmck@kernel.org>
To: Qian Cai <cai@lca.pw>
Cc: Marco Elver <elver@google.com>,
	LKMM Maintainers -- Akira Yokosawa <akiyks@gmail.com>,
	Alan Stern <stern@rowland.harvard.edu>,
	Alexander Potapenko <glider@google.com>,
	Andrea Parri <parri.andrea@gmail.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	Andy Lutomirski <luto@kernel.org>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Arnd Bergmann <arnd@arndb.de>, Boqun Feng <boqun.feng@gmail.com>,
	Borislav Petkov <bp@alien8.de>, Daniel Axtens <dja@axtens.net>,
	Daniel Lustig <dlustig@nvidia.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	David Howells <dhowells@redhat.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	Jade Alglave <j.alglave@ucl.ac.uk>,
	Joel Fernandes <joel@joelfernandes.org>
Subject: Re: [PATCH v4 01/10] kcsan: Add Kernel Concurrency Sanitizer infrastructure
Date: Tue, 14 Jan 2020 13:34:05 -0800	[thread overview]
Message-ID: <20200114213405.GX2935@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <F185919B-2D86-43B6-9BEC-D14D72871A58@lca.pw>

On Tue, Jan 14, 2020 at 03:30:53PM -0500, Qian Cai wrote:
> 
> 
> > On Jan 14, 2020, at 2:22 PM, Paul E. McKenney <paulmck@kernel.org> wrote:
> > 
> > Just so I understand...  Does this problem happen even in CONFIG_KCSAN=n
> > kernels?
> 
> No.

Whew!!!  ;-)

> > I have been running extensive CONFIG_KSCAN=y rcutorture tests for quite
> > awhile now, so even if this only happens for CONFIG_KSCAN=y, it is not
> > like it affects everyone.
> > 
> > Yes, it should be fixed, and Marco does have a patch on the way.
> 
> The concern is really about setting KSCAN=y in a distro debug kernel where it has other debug options. I’ll try to dig into more of those issues in the next few days.

Understood.  But there are likely to be other issues with KCSAN, given how
new it is.  Yes, yes, I certainly would like to believe that the patches
we currently know about will make KCSAN perfect for distros, I have way
too much grey hair (and too little hair as well!) to really beleive that.

As an alternative, once the patches needed for your tests to pass
reach mainline, you could announce that KCSAN was ready to be enabled
in distros.

Though I confess that I don't know how that works.  Is there a separate
testing kernel binary provided by the distros in question?

							Thanx, Paul

  reply	other threads:[~2020-01-14 21:34 UTC|newest]

Thread overview: 100+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-14 18:02 [PATCH v4 00/10] Add Kernel Concurrency Sanitizer (KCSAN) Marco Elver
2019-11-14 18:02 ` Marco Elver
2019-11-14 18:02 ` Marco Elver
2019-11-14 18:02 ` [PATCH v4 01/10] kcsan: Add Kernel Concurrency Sanitizer infrastructure Marco Elver
2019-11-14 18:02   ` Marco Elver
2019-11-14 18:02   ` Marco Elver
2019-11-19 19:27   ` Qian Cai
2019-11-19 19:27     ` Qian Cai
2019-11-19 19:27     ` Qian Cai
2019-11-19 19:54     ` Marco Elver
2019-11-19 19:54       ` Marco Elver
2019-11-19 19:54       ` Marco Elver
2019-11-19 21:42       ` Qian Cai
2019-11-19 21:42         ` Qian Cai
2019-11-19 21:53         ` Marco Elver
2019-11-19 21:53           ` Marco Elver
2019-11-19 21:53           ` Marco Elver
2020-01-03  5:13   ` Qian Cai
2020-01-03  5:13     ` Qian Cai
2020-01-06 12:46     ` Marco Elver
2020-01-06 12:46       ` Marco Elver
2020-01-06 12:46       ` Marco Elver
2020-01-14 11:08       ` Qian Cai
2020-01-14 11:08         ` Qian Cai
2020-01-14 12:51         ` Marco Elver
2020-01-14 12:51           ` Marco Elver
2020-01-14 12:51           ` Marco Elver
2020-01-14 19:22         ` Paul E. McKenney
2020-01-14 19:22           ` Paul E. McKenney
2020-01-14 20:30           ` Qian Cai
2020-01-14 20:30             ` Qian Cai
2020-01-14 21:34             ` Paul E. McKenney [this message]
2020-01-14 21:34               ` Paul E. McKenney
2020-01-14 21:48               ` Qian Cai
2020-01-14 21:48                 ` Qian Cai
2020-01-14 22:09                 ` Paul E. McKenney
2020-01-14 22:09                   ` Paul E. McKenney
2019-11-14 18:02 ` [PATCH v4 02/10] include/linux/compiler.h: Introduce data_race(expr) macro Marco Elver
2019-11-14 18:02   ` Marco Elver
2019-11-14 18:02   ` Marco Elver
2019-11-14 18:02 ` [PATCH v4 03/10] kcsan: Add Documentation entry in dev-tools Marco Elver
2019-11-14 18:02   ` Marco Elver
2019-11-14 18:02   ` Marco Elver
2019-11-14 18:02 ` [PATCH v4 04/10] objtool, kcsan: Add KCSAN runtime functions to whitelist Marco Elver
2019-11-14 18:02   ` Marco Elver
2019-11-14 18:02   ` Marco Elver
2019-11-14 18:02 ` [PATCH v4 05/10] build, kcsan: Add KCSAN build exceptions Marco Elver
2019-11-14 18:02   ` Marco Elver
2019-11-14 18:02   ` Marco Elver
2019-11-14 18:02 ` [PATCH v4 06/10] seqlock, kcsan: Add annotations for KCSAN Marco Elver
2019-11-14 18:02   ` Marco Elver
2019-11-14 18:02   ` Marco Elver
2019-11-14 18:03 ` [PATCH v4 07/10] seqlock: Require WRITE_ONCE surrounding raw_seqcount_barrier Marco Elver
2019-11-14 18:03   ` Marco Elver
2019-11-14 18:03   ` Marco Elver
2019-11-14 18:03 ` [PATCH v4 08/10] asm-generic, kcsan: Add KCSAN instrumentation for bitops Marco Elver
2019-11-14 18:03   ` Marco Elver
2019-11-14 18:03   ` Marco Elver
2019-11-15 11:55   ` Marco Elver
2019-11-15 11:55     ` Marco Elver
2019-11-14 18:03 ` [PATCH v4 09/10] locking/atomics, kcsan: Add KCSAN instrumentation Marco Elver
2019-11-14 18:03   ` Marco Elver
2019-11-14 18:03   ` Marco Elver
2019-11-14 18:03 ` [PATCH v4 10/10] x86, kcsan: Enable KCSAN for x86 Marco Elver
2019-11-14 18:03   ` Marco Elver
2019-11-14 18:03   ` Marco Elver
2019-11-14 19:50 ` [PATCH v4 00/10] Add Kernel Concurrency Sanitizer (KCSAN) Paul E. McKenney
2019-11-14 21:33   ` Marco Elver
2019-11-14 22:15     ` Paul E. McKenney
2019-11-15 12:02       ` Marco Elver
2019-11-15 12:02         ` Marco Elver
2019-11-15 12:02         ` Marco Elver
2019-11-15 16:41         ` Paul E. McKenney
2019-11-15 16:41           ` Paul E. McKenney
2019-11-15 17:14           ` Marco Elver
2019-11-15 17:14             ` Marco Elver
2019-11-15 17:14             ` Marco Elver
2019-11-15 20:43             ` Paul E. McKenney
2019-11-15 20:43               ` Paul E. McKenney
2019-11-16  8:20               ` Marco Elver
2019-11-16  8:20                 ` Marco Elver
2019-11-16  8:20                 ` Marco Elver
2019-11-16 15:34                 ` Paul E. McKenney
2019-11-16 15:34                   ` Paul E. McKenney
2019-11-16 18:09                   ` Marco Elver
2019-11-16 18:09                     ` Marco Elver
2019-11-16 18:09                     ` Marco Elver
2019-11-16 18:28                     ` Paul E. McKenney
2019-11-16 18:28                       ` Paul E. McKenney
2019-11-19 19:50 ` Qian Cai
2019-11-19 19:50   ` Qian Cai
2019-11-19 19:50   ` Qian Cai
2019-11-19 20:12 ` Qian Cai
2019-11-19 20:12   ` Qian Cai
2019-11-19 20:12   ` Qian Cai
2019-11-19 21:50   ` Marco Elver
2019-11-19 21:50     ` Marco Elver
2019-11-19 21:50     ` Marco Elver
2019-11-20 15:54     ` Marco Elver
2019-11-20 15:54       ` Marco Elver

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