linux-kernel - Re: [PATCH] hugetlbfs read() support

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Date:	Thu, 19 Jul 2007 09:58:50 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Badari Pulavarty <pbadari@...ibm.com>
Cc:	Bill Irwin <bill.irwin@...cle.com>, nacc@...ibm.com,
	lkml <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	Nick Piggin <nickpiggin@...oo.com.au>
Subject: Re: [PATCH] hugetlbfs read() support

On Thu, 19 Jul 2007 08:51:49 -0700 Badari Pulavarty <pbadari@...ibm.com> wrote:

> > > +		}
> > > +
> > > +		offset += ret;
> > > +		retval += ret;
> > > +		len -= ret;
> > > +		index += offset >> HPAGE_SHIFT;
> > > +		offset &= ~HPAGE_MASK;
> > > +
> > > +		page_cache_release(page);
> > > +		if (ret == nr && len)
> > > +			continue;
> > > +		goto out;
> > > +	}
> > > +out:
> > > +	return retval;
> > > +}
> > 
> > This code doesn't have all the ghastly tricks which we deploy to handle
> > concurrent truncate.
> 
> Do I need to ? Baaahh!!  I don't want to deal with them. 

Nick, can you think of any serious consequences of a read/truncate race in
there?  I can't..

> All I want is a simple read() to get my oprofile working.
> Please advise.

Did you consider changing oprofile userspace to read the executable with
mmap?
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