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61eeb9a905
scx_ops_disable_workfn() only switches !TASK_DEAD tasks out of SCX while calling scx_ops_exit_task() on all tasks including dead ones. This can leave a dead task on SCX but with SCX_TASK_NONE state, which is inconsistent. If another task was in the process of changing the TASK_DEAD task's scheduling class and grabs the rq lock after scx_ops_disable_workfn() is done with the task, the task ends up calling scx_ops_disable_task() on the dead task which is in an inconsistent state triggering a warning: WARNING: CPU: 6 PID: 3316 at kernel/sched/ext.c:3411 scx_ops_disable_task+0x12c/0x160 ... RIP: 0010:scx_ops_disable_task+0x12c/0x160 ... Call Trace: <TASK> check_class_changed+0x2c/0x70 __sched_setscheduler+0x8a0/0xa50 do_sched_setscheduler+0x104/0x1c0 __x64_sys_sched_setscheduler+0x18/0x30 do_syscall_64+0x7b/0x140 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f140d70ea5b There is no reason to leave dead tasks on SCX when unloading the BPF scheduler. Fix by making scx_ops_disable_workfn() eject all tasks including the dead ones from SCX. Signed-off-by: Tejun Heo <tj@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.