Date: Mon, 26 Jan 2009 11:09:59 -0800 (PST)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andrew Morton <akpm@linux-foundation.org>
cc: Nick Piggin <npiggin@suse.de>, mingo@elte.hu, linux-arch@vger.kernel.org,
       rusty@rustcorp.com.au, travis@sgi.com, linux-kernel@vger.kernel.org,
       venkatesh.pallipadi@intel.com, suresh.b.siddha@intel.com,
       arjan@infradead.org, hpa@zytor.com, tglx@linutronix.de
Subject: Re: [git pull] cpus4096 tree, part 3
In-Reply-To: <20090126110054.bdddbf38.akpm@linux-foundation.org>
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On Mon, 26 Jan 2009, Andrew Morton wrote:
> > +	write = error_code & PF_WRITE;
> 
> What's going on here?  We set `error_code' to PF_WRITE, which is some
> x86-specific thing.

No. We set "write" to non-zero if it was a write fault.

> >  	fault = handle_mm_fault(mm, vma, address, write);
> 
> and then pass it into handle_mm_fault(), which is expecting a bunch of
> flags in the FAULT_FLAG_foo domain.

No. "handle_mm_fault()" takes an integer that is non-zero if it's a write, 
zero if it's a read. That's how it has _always_ worked.

I don't see where you find that FAULT_FLAG_foo thing. That's much deeper 
down, when people do things like

        unsigned int flags = FAULT_FLAG_NONLINEAR |
                                (write_access ? FAULT_FLAG_WRITE : 0);

based on that whole "write_access" flag.

		Linus
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