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| author |   Jeff Layton <jlayton@kernel.org> | 2019-03-25 08:15:14 -0400 |
|---|---|---|
| committer | Jeff Layton <jlayton@kernel.org> | 2019-03-25 08:36:24 -0400 |
| commit | 945ab8f6de94430c23a82f3cf2e3f6d6f2945ff7 (patch) | |
| tree | 8f35ecd8e926416c684725ce93ee604164fd16d9 /fs | |
| parent | Linux 5.1-rc2 (diff) | |
| download | wireguard-linux-945ab8f6de94430c23a82f3cf2e3f6d6f2945ff7.tar.xz wireguard-linux-945ab8f6de94430c23a82f3cf2e3f6d6f2945ff7.zip | |
locks: wake any locks blocked on request before deadlock check
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.
While we remove the request from the blocked_lock_hash prior to
reattempting to acquire it, any locks that are blocked on that request
will still be present in the hash and will still have their fl_blocker
pointer set to the current request.
This causes posix_locks_deadlock to find a deadlock dependency chain
when it shouldn't, as a lock request cannot block itself.
We are going to end up waking all of those blocked locks anyway when we
go to reinsert the request back into the blocked_lock_hash, so just do
it prior to checking for deadlocks. This ensures that any lock blocked
on the current request will no longer be part of any blocked request
chain.
URL: https://bugzilla.kernel.org/show_bug.cgi?id=202975
Fixes: 5946c4319ebb ("fs/locks: allow a lock request to block other requests.")
Cc: stable@vger.kernel.org
Reported-by: Andreas Schneider <asn@redhat.com>
Signed-off-by: Neil Brown <neilb@suse.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/locks.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/locks.c b/fs/locks.c index eaa1cfaf73b0..71d0c6c2aac5 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -1160,6 +1160,11 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request, */ error = -EDEADLK; spin_lock(&blocked_lock_lock); + /* + * Ensure that we don't find any locks blocked on this + * request during deadlock detection. + */ + __locks_wake_up_blocks(request); if (likely(!posix_locks_deadlock(request, fl))) { error = FILE_LOCK_DEFERRED; __locks_insert_block(fl, request, |