98f1b5a762
Suspending a CPU on a RT kernel results in the following backtrace: | Disabling non-boot CPUs ... | BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917 | in_atomic(): 1, irqs_disabled(): 128, pid: 18, name: migration/1 | INFO: lockdep is turned off. | irq event stamp: 122 | hardirqs last enabled at (121): [<c06ac0ac>] _raw_spin_unlock_irqrestore+0x88/0x90 | hardirqs last disabled at (122): [<c06abed0>] _raw_spin_lock_irq+0x28/0x5c | CPU: 1 PID: 18 Comm: migration/1 Tainted: G W 4.1.4-rt3-01046-g96ac8da #204 | Hardware name: Generic DRA74X (Flattened Device Tree) | [<c0019134>] (unwind_backtrace) from [<c0014774>] (show_stack+0x20/0x24) | [<c0014774>] (show_stack) from [<c06a70f4>] (dump_stack+0x88/0xdc) | [<c06a70f4>] (dump_stack) from [<c006cab8>] (___might_sleep+0x198/0x2a8) | [<c006cab8>] (___might_sleep) from [<c06ac4dc>] (rt_spin_lock+0x30/0x70) | [<c06ac4dc>] (rt_spin_lock) from [<c013f790>] (find_lock_task_mm+0x9c/0x174) | [<c013f790>] (find_lock_task_mm) from [<c00409ac>] (clear_tasks_mm_cpumask+0xb4/0x1ac) | [<c00409ac>] (clear_tasks_mm_cpumask) from [<c00166a4>] (__cpu_disable+0x98/0xbc) | [<c00166a4>] (__cpu_disable) from [<c06a2e8c>] (take_cpu_down+0x1c/0x50) | [<c06a2e8c>] (take_cpu_down) from [<c00f2600>] (multi_cpu_stop+0x11c/0x158) | [<c00f2600>] (multi_cpu_stop) from [<c00f2a9c>] (cpu_stopper_thread+0xc4/0x184) | [<c00f2a9c>] (cpu_stopper_thread) from [<c0069058>] (smpboot_thread_fn+0x18c/0x324) | [<c0069058>] (smpboot_thread_fn) from [<c00649c4>] (kthread+0xe8/0x104) | [<c00649c4>] (kthread) from [<c0010058>] (ret_from_fork+0x14/0x3c) | CPU1: shutdown The root cause of above backtrace is task_lock() which takes a sleeping lock on -RT. To fix the issue, move clear_tasks_mm_cpumask() call from __cpu_disable() to __cpu_die() which is called on the thread which is asking for a target CPU to be shutdown. In addition, this change restores CPU hotplug functionality on ARM CPU1 can be unplugged/plugged many times. Link: http://lkml.kernel.org/r/1441995683-30817-1-git-send-email-grygorii.strashko@ti.com [bigeasy: slighty edited the commit message] Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com> Cc: <linux-arm-kernel@lists.infradead.org> Cc: Sekhar Nori <nsekhar@ti.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> |
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| fs | ||
| include | ||
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README
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.