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ff63b62d5a
There's a race between initializing the governor and userspace accessing the sysfs interface. From time to time the Intel graphics CI shows this signature: <1>[] #PF: error_code(0x0000) - not-present page <6>[] PGD 0 P4D 0 <4>[] Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI <4>[] CPU: 3 UID: 0 PID: 562 Comm: thermald Not tainted 6.14.0-rc4-CI_DRM_16208-g7e37396f86d8+ #1 <4>[] Hardware name: Intel Corporation Twin Lake Client Platform/AlderLake-N LP5 RVP, BIOS TWLNFWI1.R00.5222.A01.2405290634 05/29/2024 <4>[] RIP: 0010:policy_show+0x1a/0x40 thermald tries to read the policy file between the sysfs files being created and the governor set by thermal_set_governor(), which causes the NULL pointer dereference. Similarly to the hwmon interface, delay exposing the sysfs files to when the governor is already set. Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13655 Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com> Link: https://patch.msgid.link/20250307-thermal-sysfs-race-v1-1-8a3d4d4ac9c4@intel.com Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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.