Messages in this thread | | | Subject | Re: deadlocks caused by ext3/reiser dirty_inode calls during do_mmap_pgoff | From | Chris Mason <> | Date | Tue, 22 Jun 2004 10:43:19 -0400 |
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On Mon, 2004-06-21 at 20:13, Andrew Morton wrote:
> It's super-improbable because we fault the source page in by hand in > generic_file_aio_write_nolock() via fault_in_pages_readable(). Of course, > that prefaulting isn't 100% reliable either, because the VM can come in and > steal the page (or at least unmap its pte) before we get to doing the copy. > > I think we can fix both problems by changing filemap_copy_from_user() and > filemap_copy_from_user_iovec() to not fall back to kmap() - just fail the > copy in some way if the atomic copy failed. Then, in > generic_file_aio_write_nolock(), do a zero-length ->commit_write(), > put_page(), then go back and retry the whole thing, starting with > fault_in_pages_readable().
Oh, just realized this will break our data=ordered setup. prepare_write is going to do things like allocating blocks in the file etc etc. If we close the transaction via commit_write(0 size) and crash, we'll leak.
We might need to do prefault + pin on the user pages.
-chris
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