Re: [PATCH] Remove softlockup from invalidate_mapping_pages.

[Neil Brown]

On Thursday April 20, axboe@xxxxxxx wrote:
> > > 
> > > We're not supposed to look at page->index of an unlocked page.
> > 
> > We're not?  Does Jens know that?
> > __generic_file_splice_read seems to violate this principle!
> 
> Hmmm, where?
> 
2.6.17-rc1-mm1
fs/splice.c

static int __generic_file_splice_read(struct file *in, struct inode *pipe,
				      size_t len, unsigned int flags)
{
...snip....
	do_page_cache_readahead(mapping, in, index, nr_pages);

	/*
	 * Get as many pages from the page cache as possible..
	 * Start IO on the page cache entries we create (we
	 * can assume that any pre-existing ones we find have
	 * already had IO started on them).
	 */
	i = find_get_pages(mapping, index, nr_pages, pages);

	/*
	 * common case - we found all pages and they are contiguous,
	 * kick them off
	 */
	if (i && (pages[i - 1]->index == index + i - 1))
                  ^^^^^^^^^^^^^^^^^^^^
***There and
		goto splice_them;

	/*
	 * fill shadow[] with pages at the right locations, so we only
	 * have to fill holes
	 */
	memset(shadow, 0, nr_pages * sizeof(struct page *));
	for (j = 0; j < i; j++)
		shadow[pages[j]->index - index] = pages[j];
                      ^^^^^^^^^^^^^^^^

***There

NeilBrown
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