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Message-ID: <3A46578C.5FF7AD4F@innominate.de>
Date: Sun, 24 Dec 2000 21:07:40 +0100
From: Daniel Phillips <phillips@innominate.de>
Organization: innominate
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To: Linus Torvalds <torvalds@transmeta.com>, linux-kernel@vger.kernel.org
Subject: Re: innd mmap bug in 2.4.0-test12
In-Reply-To: <20001224170052.A223@wonderland.linux.it> <Pine.LNX.4.10.10012240941540.3972-100000@penguin.transmeta.com>
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Linus Torvalds wrote:
> Hmm.. I wonder if such a dirty page might have been moved to the
> "inactive_clean" list some way? It shouldn't really be there, as the page
> had users, but if it gets on that list we'd not have tested the dirty bit.
> 
> Marco, would you mind changing the test in reclaim_page(), somewheer
> around line mm/vmscan.c:487 that says:
> 
>         /* The page is dirty, or locked, move to inactive_dirty list. */
>         if (page->buffers || TryLockPage(page)) {
>                 ...
> 
> and change the test to
> 
>         if (page->buffers || PageDirty(page) || TryLockPage(page)) {
> 
> instead? Ie ad the test for "PageDirty(page)"

Good point.  Up until recently the page dirty bit wasn't actually being
set anywhere and page->buffers was acting as kind of a surrogate dirty
bit - page_launder would call try_to_free_buffers which would find the
dirty buffers and fail out, but start io first

It looks like PG_dirty is now being used only for swap_cache pages, and
not for buffer cache and page cache pages, is that correct?

--
Daniel
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