From: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
To: "peterz@infradead.org" <peterz@infradead.org>,
"Eugeniy.Paltsev@synopsys.com" <Eugeniy.Paltsev@synopsys.com>
Cc: "mingo@kernel.org" <mingo@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Alexey.Brodkin@synopsys.com" <Alexey.Brodkin@synopsys.com>,
"Vineet.Gupta1@synopsys.com" <Vineet.Gupta1@synopsys.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"linux-snps-arc@lists.infradead.org"
<linux-snps-arc@lists.infradead.org>,
"yamada.masahiro@socionext.com" <yamada.masahiro@socionext.com>,
"will.deacon@arm.com" <will.deacon@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Subject: Re: Patch "asm-generic/bitops/lock.h: Rewrite using atomic_fetch_" causes kernel crash
Date: Thu, 30 Aug 2018 14:46:16 +0000 [thread overview]
Message-ID: <1535640375.4465.68.camel@synopsys.com> (raw)
In-Reply-To: <20180830141713.GN24082@hirez.programming.kicks-ass.net>
On Thu, 2018-08-30 at 16:17 +0200, Peter Zijlstra wrote:
> On Thu, Aug 30, 2018 at 11:53:17AM +0000, Eugeniy Paltsev wrote:
> > I can see crashes with LLSC enabled in both SMP running on 4 cores
> > and SMP running on 1 core.
>
> So you're running on LL/SC enabled hardware; that would make Will's
> patch irrelevant (although still a good idea for the hardware that does
> care about that spinlocked atomic crud).
>
> Does something like the below cure things? That would confirm the
> suggestion that the change to __clear_bit_unlock() is the curprit.
I tested it - this doesn't change anything, the problem still reproduces.
I'll test it with last Will fix.
> If that doesn't cure things, then we've been looking in entirely the
> wrong place.
>
> ---
> diff --git a/include/asm-generic/bitops/lock.h b/include/asm-generic/bitops/lock.h
> index 3ae021368f48..79c6978152f8 100644
> --- a/include/asm-generic/bitops/lock.h
> +++ b/include/asm-generic/bitops/lock.h
> @@ -57,12 +57,7 @@ static inline void clear_bit_unlock(unsigned int nr, volatile unsigned long *p)
> static inline void __clear_bit_unlock(unsigned int nr,
> volatile unsigned long *p)
> {
> - unsigned long old;
> -
> - p += BIT_WORD(nr);
> - old = READ_ONCE(*p);
> - old &= ~BIT_MASK(nr);
> - atomic_long_set_release((atomic_long_t *)p, old);
> + clear_bit_unlock(nr, p);
> }
>
> /**
--
Eugeniy Paltsev
WARNING: multiple messages have this Message-ID (diff)
From: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
To: "peterz@infradead.org" <peterz@infradead.org>,
"Eugeniy.Paltsev@synopsys.com" <Eugeniy.Paltsev@synopsys.com>
Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"Vineet.Gupta1@synopsys.com" <Vineet.Gupta1@synopsys.com>,
"Alexey.Brodkin@synopsys.com" <Alexey.Brodkin@synopsys.com>,
"will.deacon@arm.com" <will.deacon@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"yamada.masahiro@socionext.com" <yamada.masahiro@socionext.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"linux-snps-arc@lists.infradead.org"
<linux-snps-arc@lists.infradead.org>,
"mingo@kernel.org" <mingo@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: Patch "asm-generic/bitops/lock.h: Rewrite using atomic_fetch_" causes kernel crash
Date: Thu, 30 Aug 2018 14:46:16 +0000 [thread overview]
Message-ID: <1535640375.4465.68.camel@synopsys.com> (raw)
In-Reply-To: <20180830141713.GN24082@hirez.programming.kicks-ass.net>
On Thu, 2018-08-30 at 16:17 +0200, Peter Zijlstra wrote:
> On Thu, Aug 30, 2018 at 11:53:17AM +0000, Eugeniy Paltsev wrote:
> > I can see crashes with LLSC enabled in both SMP running on 4 cores
> > and SMP running on 1 core.
>
> So you're running on LL/SC enabled hardware; that would make Will's
> patch irrelevant (although still a good idea for the hardware that does
> care about that spinlocked atomic crud).
>
> Does something like the below cure things? That would confirm the
> suggestion that the change to __clear_bit_unlock() is the curprit.
I tested it - this doesn't change anything, the problem still reproduces.
I'll test it with last Will fix.
> If that doesn't cure things, then we've been looking in entirely the
> wrong place.
>
> ---
> diff --git a/include/asm-generic/bitops/lock.h b/include/asm-generic/bitops/lock.h
> index 3ae021368f48..79c6978152f8 100644
> --- a/include/asm-generic/bitops/lock.h
> +++ b/include/asm-generic/bitops/lock.h
> @@ -57,12 +57,7 @@ static inline void clear_bit_unlock(unsigned int nr, volatile unsigned long *p)
> static inline void __clear_bit_unlock(unsigned int nr,
> volatile unsigned long *p)
> {
> - unsigned long old;
> -
> - p += BIT_WORD(nr);
> - old = READ_ONCE(*p);
> - old &= ~BIT_MASK(nr);
> - atomic_long_set_release((atomic_long_t *)p, old);
> + clear_bit_unlock(nr, p);
> }
>
> /**
--
Eugeniy Paltsev
WARNING: multiple messages have this Message-ID (diff)
From: Eugeniy.Paltsev@synopsys.com (Eugeniy Paltsev)
To: linux-snps-arc@lists.infradead.org
Subject: Patch "asm-generic/bitops/lock.h: Rewrite using atomic_fetch_" causes kernel crash
Date: Thu, 30 Aug 2018 14:46:16 +0000 [thread overview]
Message-ID: <1535640375.4465.68.camel@synopsys.com> (raw)
In-Reply-To: <20180830141713.GN24082@hirez.programming.kicks-ass.net>
On Thu, 2018-08-30@16:17 +0200, Peter Zijlstra wrote:
> On Thu, Aug 30, 2018@11:53:17AM +0000, Eugeniy Paltsev wrote:
> > I can see crashes with LLSC enabled in both SMP running on 4 cores
> > and SMP running on 1 core.
>
> So you're running on LL/SC enabled hardware; that would make Will's
> patch irrelevant (although still a good idea for the hardware that does
> care about that spinlocked atomic crud).
>
> Does something like the below cure things? That would confirm the
> suggestion that the change to __clear_bit_unlock() is the curprit.
I tested it - this doesn't change anything, the problem still reproduces.
I'll test it with last Will fix.
> If that doesn't cure things, then we've been looking in entirely the
> wrong place.
>
> ---
> diff --git a/include/asm-generic/bitops/lock.h b/include/asm-generic/bitops/lock.h
> index 3ae021368f48..79c6978152f8 100644
> --- a/include/asm-generic/bitops/lock.h
> +++ b/include/asm-generic/bitops/lock.h
> @@ -57,12 +57,7 @@ static inline void clear_bit_unlock(unsigned int nr, volatile unsigned long *p)
> static inline void __clear_bit_unlock(unsigned int nr,
> volatile unsigned long *p)
> {
> - unsigned long old;
> -
> - p += BIT_WORD(nr);
> - old = READ_ONCE(*p);
> - old &= ~BIT_MASK(nr);
> - atomic_long_set_release((atomic_long_t *)p, old);
> + clear_bit_unlock(nr, p);
> }
>
> /**
--
Eugeniy Paltsev
WARNING: multiple messages have this Message-ID (diff)
From: Eugeniy.Paltsev@synopsys.com (Eugeniy Paltsev)
To: linux-arm-kernel@lists.infradead.org
Subject: Patch "asm-generic/bitops/lock.h: Rewrite using atomic_fetch_" causes kernel crash
Date: Thu, 30 Aug 2018 14:46:16 +0000 [thread overview]
Message-ID: <1535640375.4465.68.camel@synopsys.com> (raw)
In-Reply-To: <20180830141713.GN24082@hirez.programming.kicks-ass.net>
On Thu, 2018-08-30 at 16:17 +0200, Peter Zijlstra wrote:
> On Thu, Aug 30, 2018 at 11:53:17AM +0000, Eugeniy Paltsev wrote:
> > I can see crashes with LLSC enabled in both SMP running on 4 cores
> > and SMP running on 1 core.
>
> So you're running on LL/SC enabled hardware; that would make Will's
> patch irrelevant (although still a good idea for the hardware that does
> care about that spinlocked atomic crud).
>
> Does something like the below cure things? That would confirm the
> suggestion that the change to __clear_bit_unlock() is the curprit.
I tested it - this doesn't change anything, the problem still reproduces.
I'll test it with last Will fix.
> If that doesn't cure things, then we've been looking in entirely the
> wrong place.
>
> ---
> diff --git a/include/asm-generic/bitops/lock.h b/include/asm-generic/bitops/lock.h
> index 3ae021368f48..79c6978152f8 100644
> --- a/include/asm-generic/bitops/lock.h
> +++ b/include/asm-generic/bitops/lock.h
> @@ -57,12 +57,7 @@ static inline void clear_bit_unlock(unsigned int nr, volatile unsigned long *p)
> static inline void __clear_bit_unlock(unsigned int nr,
> volatile unsigned long *p)
> {
> - unsigned long old;
> -
> - p += BIT_WORD(nr);
> - old = READ_ONCE(*p);
> - old &= ~BIT_MASK(nr);
> - atomic_long_set_release((atomic_long_t *)p, old);
> + clear_bit_unlock(nr, p);
> }
>
> /**
--
Eugeniy Paltsev
next prev parent reply other threads:[~2018-08-30 14:47 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-29 18:33 Patch "asm-generic/bitops/lock.h: Rewrite using atomic_fetch_" causes kernel crash Eugeniy Paltsev
2018-08-29 18:33 ` Eugeniy Paltsev
2018-08-29 18:33 ` Eugeniy Paltsev
2018-08-29 18:33 ` Eugeniy Paltsev
2018-08-29 21:16 ` Vineet Gupta
2018-08-29 21:16 ` Vineet Gupta
2018-08-29 21:16 ` Vineet Gupta
2018-08-29 21:16 ` Vineet Gupta
2018-08-30 9:35 ` Will Deacon
2018-08-30 9:35 ` Will Deacon
2018-08-30 9:35 ` Will Deacon
2018-08-30 9:35 ` Will Deacon
2018-08-30 9:44 ` Peter Zijlstra
2018-08-30 9:44 ` Peter Zijlstra
2018-08-30 9:44 ` Peter Zijlstra
2018-08-30 9:44 ` Peter Zijlstra
2018-08-30 9:44 ` Peter Zijlstra
2018-08-30 9:51 ` Will Deacon
2018-08-30 9:51 ` Will Deacon
2018-08-30 9:51 ` Will Deacon
2018-08-30 9:51 ` Will Deacon
2018-08-30 11:53 ` Eugeniy Paltsev
2018-08-30 11:53 ` Eugeniy Paltsev
2018-08-30 11:53 ` Eugeniy Paltsev
2018-08-30 11:53 ` Eugeniy Paltsev
2018-08-30 13:57 ` Will Deacon
2018-08-30 13:57 ` Will Deacon
2018-08-30 13:57 ` Will Deacon
2018-08-30 13:57 ` Will Deacon
2018-08-30 14:17 ` Peter Zijlstra
2018-08-30 14:17 ` Peter Zijlstra
2018-08-30 14:17 ` Peter Zijlstra
2018-08-30 14:17 ` Peter Zijlstra
2018-08-30 14:17 ` Peter Zijlstra
2018-08-30 14:23 ` Will Deacon
2018-08-30 14:23 ` Will Deacon
2018-08-30 14:23 ` Will Deacon
2018-08-30 14:23 ` Will Deacon
2018-08-30 14:29 ` Peter Zijlstra
2018-08-30 14:29 ` Peter Zijlstra
2018-08-30 14:29 ` Peter Zijlstra
2018-08-30 14:29 ` Peter Zijlstra
2018-08-30 14:43 ` Peter Zijlstra
2018-08-30 14:43 ` Peter Zijlstra
2018-08-30 14:43 ` Peter Zijlstra
2018-08-30 14:43 ` Peter Zijlstra
2018-08-30 14:43 ` Peter Zijlstra
2020-04-14 1:19 ` Vineet Gupta
2020-04-14 1:19 ` Vineet Gupta
2020-04-14 1:19 ` Vineet Gupta
2020-04-14 1:19 ` Vineet Gupta
2018-08-30 20:31 ` Vineet Gupta
2018-08-30 20:31 ` Vineet Gupta
2018-08-30 20:31 ` Vineet Gupta
2018-08-30 20:31 ` Vineet Gupta
2018-08-30 20:45 ` Peter Zijlstra
2018-08-30 20:45 ` Peter Zijlstra
2018-08-30 20:45 ` Peter Zijlstra
2018-08-30 20:45 ` Peter Zijlstra
2018-08-30 20:45 ` Peter Zijlstra
2018-08-31 0:30 ` Vineet Gupta
2018-08-31 0:30 ` Vineet Gupta
2018-08-31 0:30 ` Vineet Gupta
2018-08-31 0:30 ` Vineet Gupta
2018-08-31 9:53 ` Will Deacon
2018-08-31 9:53 ` Will Deacon
2018-08-31 9:53 ` Will Deacon
2018-08-31 9:53 ` Will Deacon
2018-08-30 14:46 ` Eugeniy Paltsev [this message]
2018-08-30 14:46 ` Eugeniy Paltsev
2018-08-30 14:46 ` Eugeniy Paltsev
2018-08-30 14:46 ` Eugeniy Paltsev
2018-08-30 14:46 ` Eugeniy Paltsev
2018-08-30 17:15 ` Peter Zijlstra
2018-08-30 17:15 ` Peter Zijlstra
2018-08-30 17:15 ` Peter Zijlstra
2018-08-30 17:15 ` Peter Zijlstra
2018-08-31 0:42 ` Vineet Gupta
2018-08-31 0:42 ` Vineet Gupta
2018-08-31 0:42 ` Vineet Gupta
2018-08-31 0:42 ` Vineet Gupta
2018-08-31 0:29 ` __clear_bit_lock to use atomic clear_bit (was Re: Patch "asm-generic/bitops/lock.h) Vineet Gupta
2018-08-31 0:29 ` Vineet Gupta
2018-08-31 0:29 ` Vineet Gupta
2018-08-31 0:29 ` Vineet Gupta
2018-08-31 7:24 ` Peter Zijlstra
2018-08-31 7:24 ` Peter Zijlstra
2018-08-31 7:24 ` Peter Zijlstra
2018-08-31 7:24 ` Peter Zijlstra
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