On Sun, Dec 10, 2017 at 10:50:17PM -0500, Theodore Ts'o wrote:

CONFIG_LOCKDEP_CROSSRELEASE and CONFIG_LOCKDEP_COMPLETIONS can result
in a large number of false positives because lockdep doesn't
understand how to deal with multiple stacked loop or MD devices.

Until someone can figure out how to automatically add annotations to
all file system and storage devices --- hopefully without forcing
developers to insert a large number of calls to undocumented lockdep
macros into the the loop device, every single file system, and every
single device-mapper backend --- let's add an option to allow these
lockdep features to be disabled.  Otherwise, many file system
developers will disable LOCKDEP entirely since it results in far too
many false positives when trying to use xfstests.

Note --- this is going to be in the ext4 git tree because otherwise
using Lockdep would greatly interfere with ext4 development --- and
I'd prefer not to completely give up on Lockdep as a lost cause.  As
such, it will appear in linux-next.

I'll drop it from the ext4 git branch before I send a pull request to
Linus, unless I get an OK for me to merge this patch to mainline via
the ext4 git tree.

Cheers,

						- Ted