On Tue, 8 Mar 2011, Lukas Czerner wrote:
On Tue, 8 Mar 2011, Zhang Huan wrote:
Hi all,
There is potential memory leak of journal head in function
jbd2_journal_commit_transaction. The problem is that JBD2 will not
reclaim the journal head of commit record if error occurs or journal is
abotred.
I use the following script to reproduce this issue, on a RHEL6 system. I
found it very easy to reproduce with async commit enabled.
mount /dev/sdb /mnt -o journal_checksum,journal_async_commit
touch /mnt/xxx
echo offline > /sys/block/sdb/device/state
sync
umount /mnt
rmmod ext4
rmmod jbd2
Removal of the jbd2 module will make slab complaining that
"cache `jbd2_journal_head': can't free all objects".
Here is my fix for this issue. The commit record should be reclaimed no
matter error occurs or not.
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index f3ad159..37a973a 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -105,6 +105,8 @@ static int journal_submit_commit_record(journal_t *journal,
int ret;
struct timespec now = current_kernel_time();
+ *cbh = NULL;
+
if (is_journal_aborted(journal))
return 0;
@@ -808,7 +810,7 @@ wait_for_iobuf:
if (err)
__jbd2_journal_abort_hard(journal);
}
- if (!err && !is_journal_aborted(journal))
+ if (cbh)
Hi,
I wonder if we could do rather this:
if (!err && !is_journal_aborted(journal))
err = journal_wait_on_commit_record(journal, cbh);
else if (cbh) {
put_bh(cbh);
jbd2_journal_put_journal_head(bh2jh(cbh));
}
I think this is more readable...
Hi,
I don't think it is a good idea. Anyway, you need to wait for buffer to
complete, and then release journal head on it. That is exactly what
journal_wait_on_commit_record does.
Thanks!
-Lukas
err = journal_wait_on_commit_record(journal, cbh);
if (JBD2_HAS_INCOMPAT_FEATURE(journal,
JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT) &&
PS: Just out of curiosity, why would journal_submit_commit_record return a
value of 1 instead of an error number if get descriptor buffer is failed.
Zhang Huan
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Zhang Huan
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