5.0-stable review patch. If anyone has any objections, please let me know.
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From: Jeff Layton jlayton@kernel.org
commit 945ab8f6de94430c23a82f3cf2e3f6d6f2945ff7 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/locks.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/fs/locks.c +++ b/fs/locks.c @@ -1160,6 +1160,11 @@ static int posix_lock_inode(struct inode */ 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,