From: Fengguang Wu <fengguang.wu@intel.com>
To: Borislav Petkov <bp@amd64.org>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Jan Kara <jack@suse.cz>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <jweiner@redhat.com>,
Conny Seidel <conny.seidel@amd.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: divide error: bdi_dirty_limit+0x5a/0x9e
Date: Mon, 24 Sep 2012 20:29:00 +0800 [thread overview]
Message-ID: <20120924122900.GA28627@localhost> (raw)
In-Reply-To: <20120924122053.GD22303@aftab.osrc.amd.com>
On Mon, Sep 24, 2012 at 02:20:53PM +0200, Borislav Petkov wrote:
> On Mon, Sep 24, 2012 at 07:34:47PM +0800, Fengguang Wu wrote:
> > Will you test such a line? At least the generic do_div() only uses the
> > lower 32bits for division.
> >
> > WARN_ON(!(den & 0xffffffff));
>
> But, but, the asm output says:
>
> 28: 48 89 c8 mov %rcx,%rax
> 2b:* 48 f7 f7 div %rdi <-- trapping instruction
> 2e: 31 d2 xor %edx,%edx
>
> and this version of DIV does an unsigned division of RDX:RAX by the
> contents of a *64-bit register* ... in our case %rdi.
>
> Srivatsa's oops shows the same:
>
> 28: 48 89 f0 mov %rsi,%rax
> 2b:* 48 f7 f7 div %rdi <-- trapping instruction
> 2e: 41 8b 94 24 74 02 00 mov 0x274(%r12),%edx
>
> Right?
Right, that's why I said "at least". As for x86, I'm as clueless as you..
Thanks,
Fengguang
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next prev parent reply other threads:[~2012-09-24 12:29 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-24 10:23 divide error: bdi_dirty_limit+0x5a/0x9e Borislav Petkov
2012-09-24 10:38 ` Srivatsa S. Bhat
2012-09-24 11:05 ` Borislav Petkov
2012-09-24 11:13 ` Srivatsa S. Bhat
2012-09-24 11:34 ` Fengguang Wu
2012-09-24 11:51 ` Srivatsa S. Bhat
2012-09-24 12:20 ` Borislav Petkov
2012-09-24 12:29 ` Fengguang Wu [this message]
2012-09-24 12:56 ` Borislav Petkov
2012-09-24 18:54 ` Srivatsa S. Bhat
2012-09-24 14:23 ` Jan Kara
2012-09-24 14:36 ` Borislav Petkov
2012-09-24 18:16 ` Conny Seidel
2012-09-24 18:19 ` Borislav Petkov
2012-09-24 18:48 ` Srivatsa S. Bhat
2012-09-24 19:31 ` Borislav Petkov
2012-09-24 20:07 ` Jan Kara
2012-09-24 20:17 ` Jan Kara
2012-09-24 21:21 ` Andrew Morton
2012-09-24 22:27 ` Jan Kara
2012-09-25 8:57 ` Conny Seidel
2012-09-24 20:48 ` [PATCH] CPU hotplug, writeback: Don't call writeback_set_ratelimit() too often during hotplug Srivatsa S. Bhat
2012-09-28 12:27 ` Fengguang Wu
2012-09-28 14:46 ` Srivatsa S. Bhat
2012-10-03 23:11 ` Ni zhan Chen
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