On 04/22/2014 02:36 PM, Linus Torvalds wrote:
> That said, Dave Hansen did report a BUG_ON() in
> mpage_prepare_extent_to_map(). His line number was odd, but I assume
> it's this one:
>
> BUG_ON(PageWriteback(page));
>
> which may be indicative of some oddity here wrt the dirty bit.
I just triggered it a second time. It only happens with my debugging
config[1] *and* those two fix patches. It doesn't happen on the vanilla
kernel with lost dirty bit.
The line numbers point to the
head = page_buffers(page);
which is:
#define page_buffers(page) \
({ \
BUG_ON(!PagePrivate(page)); \
((struct buffer_head *)page_private(page)); \
})
1.
http://sr71.net/~dave/intel/20140422-lostdirtybit/config-ext4-bugon.20140422
Config that doesn't trigger it:
http://sr71.net/~dave/intel/20140422-lostdirtybit/config-ext4-nobug.20140422
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