be647e2c76
The nvme pci driver synchronizes with all the namespace queues during a reset to ensure that there's no pending timeout work. Meanwhile the timeout work potentially iterates those same namespaces to freeze their queues. Each of those namespace iterations use the same read lock. If a write lock should somehow get between the synchronize and freeze steps, then forward progress is deadlocked. We had been relying on the nvme controller state machine to ensure the reset work wouldn't conflict with timeout work. That guarantee may be a bit fragile to rely on, so iterate the namespace lists without taking potentially circular locks, as reported by lockdep. Link: https://lore.kernel.org/all/20220930001943.zdbvolc3gkekfmcv@shindev/ Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com> Tested-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Keith Busch <kbusch@kernel.org>
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.