I believe not. Please do double-check my assertions, I've always found
the _writepages paths rather twisty; but my belief (supported by the
fact that we've not hit shmem_writepage's BUG_ON(page_mapped(page))
in five years) is that tmpfs/shmem opts out of all of that with its
.capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
in shmem_backing_dev_info, which avoids all those _writepages avenues
(e.g. through bdi_cap_writeback_dirty tests), and write_cache_pages is
just a subfunction of the _writepages.
So, while I don't disagree with your patch to write_cache_pages (though
it wasn't clear to me whether it should break from or continue the loop
if it ever does meet an AOP_WRITEPAGE_ACTIVATE), I don't think that's
really the root of the problem.
Hugh
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