The patch title locks: ignore same lock in blocked_lock_hash is a bit misleading the lock isn't in the hash, but it is linked from something that is. Maybe locks: ignore same lock in posix_locks_deadlock() ?? On Sat, Mar 23 2019, Jeff Layton wrote: > Andreas reported that he was seeing the tdbtorture test fail in > some cases with -EDEADLCK when it wasn't before. Some debugging > showed that deadlock detection was sometimes discovering the > caller's lock request itself in a dependency chain. > > If posix_locks_deadlock() fails to find a deadlock, the caller_fl > will be passed to __locks_insert_block(), and this wakes up all > locks that are blocked on caller_fl, clearing the fl_blocker link. > > So if posix_locks_deadlock() finds caller_fl while searching for > a deadlock, it can be sure that link in the cycle is about to be > broken and it need not treat it as the cause of a deadlock. > > URL: https://bugzilla.kernel.org/show_bug.cgi?id=202975 > Fixes: 5946c4319ebb ("fs/locks: allow a lock request to block other requests.") > Cc: stable@xxxxxxxxxxxxxxx > Reported-by: Andreas Schneider <asn@xxxxxxxxxx> > Signed-off-by: Neil Brown <neilb@xxxxxxxx> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > --- > fs/locks.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/fs/locks.c b/fs/locks.c > index eaa1cfaf73b0..a939a274dc71 100644 > --- a/fs/locks.c > +++ b/fs/locks.c > @@ -1023,6 +1023,19 @@ static int posix_locks_deadlock(struct file_lock *caller_fl, > while ((block_fl = what_owner_is_waiting_for(block_fl))) { > if (i++ > MAX_DEADLK_ITERATIONS) > return 0; > + > + /* > + * It's possible that we're retrying this lock request after > + * another task is has blocked on it. A lock request can't > + * block itself, and any locks that are blocked on it will > + * also be awoken soon (and have their fl_blocker pointer > + * cleared). Any dependency chain that contains the request > + * itself is therefore about to be broken, so we can safely > + * ignore it. That first sentence isn't working for me .... maybe remove the "is" ?? Thanks, NeilBrown > + */ > + if (block_fl == caller_fl) > + return 0; > + > if (posix_same_owner(caller_fl, block_fl)) > return 1; > } > -- > 2.20.1
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