- Marcelo
On Mon, 27 Sep 1999, Mikael Pettersson wrote:
> Setting up a loop device on top of a newly created regular file
> triggers lots of "hm, busy page invalidated? (not necesserily a bug)"
> warnings from mm/filemap.c:invalidate_inode_pages().
>
> For example, if I do the following:
>
> rm -f /tmp/junk
> dd if=/dev/zero of=/tmp/junk bs=1k count=1024
> losetup /dev/loop0 /tmp/junk
>
> the kernel message buffer immediately fills with the abovementioned
> warning. This happens in all kernels >= 2.3.7.
>
> The message is generated by this test in invalidate_inode_pages():
>
> get_page(page);
> ...
> if (page_count(page) != 2)
> printk("hm, busy page invalidated? (not necesserily a bug)\n");
>
> When drivers/block/loop.c:loop_set_fd() calls invalidate_inode_pages(),
> it seems that each page in the backing file already has a count of 2,
> so at the test the count is 3, which triggers the message.
>
> I haven't noticed any other negative effects when using loop devices
> (no kernel instability or data corruption) so I suspect the test is
> bogus and should be removed or modified.
>
> What sayeth the VFS/page cache experts?
>
>
> /Mikael
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