Re: [BUG] 2.6.26-rc5-mm3 kernel BUG at mm/filemap.c:575!

[KAMEZAWA Hiroyuki]

On Thu, 12 Jun 2008 21:38:59 +1000
Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:

> +int putback_lru_page(struct page *page)
> +{
> +       int lru;
> +       int ret = 1;
> +       int was_unevictable;
> +
> +       VM_BUG_ON(!PageLocked(page));
> +       VM_BUG_ON(PageLRU(page));
> +
> +       lru = !!TestClearPageActive(page);
> +       was_unevictable = TestClearPageUnevictable(page); /* for 
> page_evictable() */
> +
> +       if (unlikely(!page->mapping)) {
> +               /*
> +                * page truncated.  drop lock as put_page() will
> +                * free the page.
> +                */
> +               VM_BUG_ON(page_count(page) != 1);
> +               unlock_page(page);
>                 ^^^^^^^^^^^^^^^^^^
> 
> 
> This is a rather wild thing to be doing. It's a really bad idea
> to drop a lock that's taken several function calls distant and
> across different files...
> 
I agree and strongly hope this unlock should be removed.
The caller can do unlock by itself, I think.

Thanks,
-Kame

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