mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-06 10:58:48 +09:00
497f3d9c3f
[ Upstream commitdc87740c8a] If rcu_print_task_stall() is invoked on an rcu_node structure that does not contain any tasks blocking the current grace period, it takes an early exit that fails to release that rcu_node structure's lock. This results in a self-deadlock, which is detected by lockdep. To reproduce this bug: tools/testing/selftests/rcutorture/bin/kvm.sh --allcpus --duration 3 --trust-make --configs "TREE03" --kconfig "CONFIG_PROVE_LOCKING=y" --bootargs "rcutorture.stall_cpu=30 rcutorture.stall_cpu_block=1 rcutorture.fwd_progress=0 rcutorture.test_boost=0" This will also result in other complaints, including RCU's scheduler hook complaining about blocking rather than preemption and an rcutorture writer stall. Only a partial RCU CPU stall warning message will be printed because of the self-deadlock. This commit therefore releases the lock on the rcu_print_task_stall() function's early exit path. Fixes:c583bcb8f5("rcu: Don't invoke try_invoke_on_locked_down_task() with irqs disabled") Tested-by: Qais Yousef <qais.yousef@arm.com> Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Sasha Levin <sashal@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 Restructured Text 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.