jbd: check for error returned by kthread_create on creating journal thread
If the thread failed to create the subsequent wait_event will hang forever.
This is likely to happen if kernel hits max_threads limit.
Will be critical for virtualization systems that limit the number of tasks
and kernel memory usage within the container.
(akpm: JBD should be converted fully to the kthread API: kthread_should_stop()
and kthread_stop()).
Cc: <linux-ext4@vger.kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 6b3158e..78d63b8 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -210,10 +210,16 @@
return 0;
}
-static void jbd2_journal_start_thread(journal_t *journal)
+static int jbd2_journal_start_thread(journal_t *journal)
{
- kthread_run(kjournald2, journal, "kjournald2");
+ struct task_struct *t;
+
+ t = kthread_run(kjournald2, journal, "kjournald2");
+ if (IS_ERR(t))
+ return PTR_ERR(t);
+
wait_event(journal->j_wait_done_commit, journal->j_task != 0);
+ return 0;
}
static void journal_kill_thread(journal_t *journal)
@@ -839,8 +845,7 @@
/* Add the dynamic fields and write it to disk. */
jbd2_journal_update_superblock(journal, 1);
- jbd2_journal_start_thread(journal);
- return 0;
+ return jbd2_journal_start_thread(journal);
}
/**