linux-kernel - Re: Spinlocks waiting with interrupts disabled / preempt disabled.

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Message-ID: <Pine.LNX.4.64.0805091059050.19252@schroedinger.engr.sgi.com>
Date:	Fri, 9 May 2008 11:00:22 -0700 (PDT)
From:	Christoph Lameter <clameter@....com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
cc:	Olaf Weber <olaf@....com>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org, npiggin@...e.de
Subject: Re: Spinlocks waiting with interrupts disabled / preempt disabled.

On Fri, 9 May 2008, Peter Zijlstra wrote:

> > A third solution would be to look at this problem on a case-by-case
> > basis.  In the case under discussion, there may be other kernel bugs
> > that aggravate the problem (it is an old kernel after all) and maybe
> > this just means the address_space.tree_lock ought to be replaced with
> > something else (though I wouldn't claim to know what).
> 
> That has been done by Nick Piggin, the lockless pagecache work removes
> the read side of the tree_lock.

When is that going to get merged? find_get_page is still:

struct page * find_get_page(struct address_space *mapping, pgoff_t offset)
{
        struct page *page;

        read_lock_irq(&mapping->tree_lock);
        page = radix_tree_lookup(&mapping->page_tree, offset);
        if (page)
                page_cache_get(page);
        read_unlock_irq(&mapping->tree_lock);
        return page;
}
EXPORT_SYMBOL(find_get_page);

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