375476c414
This adds lockdep tracking for held btree locks with a single dep_map in btree_trans, i.e. tracking all held btree locks as one object. This is more practical and more useful than having lockdep track held btree locks individually, because - we can take more locks than lockdep can track (unbounded, now that we have dynamically resizable btree paths) - there's no lock ordering between btree locks for lockdep to track (we do cycle detection) - and this makes it easy to teach lockdep that btree locks are not safe to hold while invoking memory reclaim. The last rule is one that lockdep would never learn, because we only do trylock() from within shrinkers - but we very much do not want to be invoking memory reclaim while holding btree node locks. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.