| Message ID | 20170411134644.9354-1-jack@suse.cz |
|---|---|
| State | Awaiting Upstream, archived |
| Headers | show |
On Tue, Apr 11, 2017 at 03:46:44PM +0200, Jan Kara wrote: > I've hit a lockdep splat with generic/270 test complaining that: > > 3216.fsstress.b/3533 is trying to acquire lock: > (jbd2_handle){++++..}, at: [<ffffffff813152e0>] jbd2_log_wait_commit+0x0/0x150 > > but task is already holding lock: > (jbd2_handle){++++..}, at: [<ffffffff8130bd3b>] start_this_handle+0x35b/0x850 > > The underlying problem is that jbd2_journal_force_commit_nested() > (called from ext4_should_retry_alloc()) may get called while a > transaction handle is started. In such case it takes care to not wait > for commit of the running transaction (which would deadlock) but only > for a commit of a transaction that is already committing (which is safe > as that doesn't wait for any filesystem locks). > > In fact there are also other callers of jbd2_log_wait_commit() that take > care to pass tid of a transaction that is already committing and for > those cases, the lockdep instrumentation is too restrictive and leading > to false positive reports. Fix the problem by calling > jbd2_might_wait_for_commit() from jbd2_log_wait_commit() only if the > transaction isn't already committing. > > Fixes: 1eaa566d368b214d99cbb973647c1b0b8102a9ae > Signed-off-by: Jan Kara <jack@suse.cz> Thanks, applied. - Ted
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index 5adc2fb62b0f..9410ec462ba6 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -691,8 +691,21 @@ int jbd2_log_wait_commit(journal_t *journal, tid_t tid) { int err = 0; - jbd2_might_wait_for_commit(journal); read_lock(&journal->j_state_lock); +#ifdef CONFIG_PROVE_LOCKING + /* + * Some callers make sure transaction is already committing and in that + * case we cannot block on open handles anymore. So don't warn in that + * case. + */ + if (tid_gt(tid, journal->j_commit_sequence) && + (!journal->j_committing_transaction || + journal->j_committing_transaction->t_tid != tid)) { + read_unlock(&journal->j_state_lock); + jbd2_might_wait_for_commit(journal); + read_lock(&journal->j_state_lock); + } +#endif #ifdef CONFIG_JBD2_DEBUG if (!tid_geq(journal->j_commit_request, tid)) { printk(KERN_ERR
I've hit a lockdep splat with generic/270 test complaining that: 3216.fsstress.b/3533 is trying to acquire lock: (jbd2_handle){++++..}, at: [<ffffffff813152e0>] jbd2_log_wait_commit+0x0/0x150 but task is already holding lock: (jbd2_handle){++++..}, at: [<ffffffff8130bd3b>] start_this_handle+0x35b/0x850 The underlying problem is that jbd2_journal_force_commit_nested() (called from ext4_should_retry_alloc()) may get called while a transaction handle is started. In such case it takes care to not wait for commit of the running transaction (which would deadlock) but only for a commit of a transaction that is already committing (which is safe as that doesn't wait for any filesystem locks). In fact there are also other callers of jbd2_log_wait_commit() that take care to pass tid of a transaction that is already committing and for those cases, the lockdep instrumentation is too restrictive and leading to false positive reports. Fix the problem by calling jbd2_might_wait_for_commit() from jbd2_log_wait_commit() only if the transaction isn't already committing. Fixes: 1eaa566d368b214d99cbb973647c1b0b8102a9ae Signed-off-by: Jan Kara <jack@suse.cz> --- fs/jbd2/journal.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)