On Feb 21, 2007, at 12:35 AM, Ken Chen wrote:
On 2/20/07, Ananiev, Leonid <[email protected]> wrote:
1) mem=1G in kernel boot param if you have more
2) unmount; mk2fs; mount
3) dd if=/dev/zero of=<test_file> bs=1M count=1200
4) aiostress -s 1200m -O -o 2 -i 1 -r 16k <test_file>
5) if i++<50 goto 2).
Would you please instrument the call chain of
invalidate_complete_page2() and tell us exactly where it returns zero
value in your failure case?
invalidate_complete_page2
try_to_release_page
ext3_releasepage
journal_try_to_free_buffers
???
For what it's worth, Badari has explained this race in the past in a
credible way. I'll take the liberty of pasting a mail from him:
"
kjournald submited buffers for IO and waiting for them to finish.
Note that it has a ref. against the buffer.
journal_commit_transaction()
...
submited buffers for IO
/* Waiting for IO to complete */
while (commit_transaction->t_locked_list) {
...
get_bh(bh);
if (buffer_locked(bh)) {
spin_unlock(&journal->j_list_lock);
wait_on_buffer(bh); <<<<<<
spin_lock(&journal->j_list_lock);
}
..
put_bh(bh);
}
Now, DIO process comes to frees the jh through
journal_try_to_free_buffers()
but fails to drop_buffers() since kjournald() has a reference against
it.
invalidate_inode_pages2_range()
..
ext3_releasepage()
journal_try_to_free_buffers()
journal_put_journal_head()
__journal_try_to_free_buffer()
<--- freed jh
try_to_free_buffers()
drop_buffers()
if (buffer_busy(bh))
goto failed;
<<--- returns EIO due to
b_count
"
I don't mean to say that we shouldn't get traces to confirm the
theory, just sharing. And now we can point to this in the archives
next time :).
- z
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