29368e0939
The call to rcu_cpu_starting() in mtrr_ap_init() is not early enough in the CPU-hotplug onlining process, which results in lockdep splats as follows: ============================= WARNING: suspicious RCU usage 5.9.0+ #268 Not tainted ----------------------------- kernel/kprobes.c:300 RCU-list traversed in non-reader section!! other info that might help us debug this: RCU used illegally from offline CPU! rcu_scheduler_active = 1, debug_locks = 1 no locks held by swapper/1/0. stack backtrace: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.9.0+ #268 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-1ubuntu1 04/01/2014 Call Trace: dump_stack+0x77/0x97 __is_insn_slot_addr+0x15d/0x170 kernel_text_address+0xba/0xe0 ? get_stack_info+0x22/0xa0 __kernel_text_address+0x9/0x30 show_trace_log_lvl+0x17d/0x380 ? dump_stack+0x77/0x97 dump_stack+0x77/0x97 __lock_acquire+0xdf7/0x1bf0 lock_acquire+0x258/0x3d0 ? vprintk_emit+0x6d/0x2c0 _raw_spin_lock+0x27/0x40 ? vprintk_emit+0x6d/0x2c0 vprintk_emit+0x6d/0x2c0 printk+0x4d/0x69 start_secondary+0x1c/0x100 secondary_startup_64_no_verify+0xb8/0xbb This is avoided by moving the call to rcu_cpu_starting up near the beginning of the start_secondary() function. Note that the raw_smp_processor_id() is required in order to avoid calling into lockdep before RCU has declared the CPU to be watched for readers. Link: https://lore.kernel.org/lkml/160223032121.7002.1269740091547117869.tip-bot2@tip-bot2/ Reported-by: Qian Cai <cai@redhat.com> Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> |
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| LICENSES | ||
| arch | ||
| block | ||
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| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
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| Makefile | ||
| README | ||
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.
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.