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commit 3ddf944b32f88741c303f0b21459dbb3872b8bc5 upstream. Modifying a MCA bank's MCA_CTL bits which control which error types to be reported is done over /sys/devices/system/machinecheck/ ├── machinecheck0 │ ├── bank0 │ ├── bank1 │ ├── bank10 │ ├── bank11 ... sysfs nodes by writing the new bit mask of events to enable. When the write is accepted, the kernel deletes all current timers and reinits all banks. Doing that in parallel can lead to initializing a timer which is already armed and in the timer wheel, i.e., in use already: ODEBUG: init active (active state 0) object: ffff888063a28000 object type: timer_list hint: mce_timer_fn+0x0/0x240 arch/x86/kernel/cpu/mce/core.c:2642 WARNING: CPU: 0 PID: 8120 at lib/debugobjects.c:514 debug_print_object+0x1a0/0x2a0 lib/debugobjects.c:514 Fix that by grabbing the sysfs mutex as the rest of the MCA sysfs code does. Reported by: Yue Sun <samsun1006219@gmail.com> Reported by: xingwei lee <xrivendell7@gmail.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Cc: <stable@kernel.org> Link: https://lore.kernel.org/r/CAEkJfYNiENwQY8yV1LYJ9LjJs%2Bx_-PqMv98gKig55=2vbzffRw@mail.gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.