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Date: Mon, 09 Sep 2002 15:07:16 -0700
From: Andrew Morton <akpm@digeo.com>
MIME-Version: 1.0
Subject: Re: [PATCH] slabasap-mm5_A2
References: <200209071006.18869.tomlins@cam.org> <200209081142.02839.tomlins@cam.org> <3D7BB97A.6B6E4CA5@digeo.com> <200209091733.44112.tomlins@cam.org>
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To: Ed Tomlinson <tomlins@cam.org>
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Ed Tomlinson wrote:
> 
> Hi Andrew,
> 
> Found three oops when checking this afternoon's log.  Looks like *total_scanned can
> be zero...
> 
> how about;
> 
> ratio = pages > *total_scanned ? pages / (*total_scanned | 1) : 1;
> 

Yup, thanks.  I went the "+ 1" route ;)

Found another dumb bug in there too.  In refill_inactive_zone:

        while (nr_pages && !list_empty(&zone->active_list)) {
		...
                if (page_count(page) == 0) {
                        /* It is currently in pagevec_release() */
                        SetPageLRU(page);
                        list_add(&page->lru, &zone->active_list);
                        continue;
                }
                page_cache_get(page);
                list_add(&page->lru, &l_hold);
                nr_pages--;
        }

does not terminate if the active list consists entirely of zero-count
pages.  I'm not sure how I managed to abuse the system into that
state, but I did, and received a visit from the NMI watchdog for my
sins.
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