510c5f5e48
commit b212b79768ccde74429f872c37618c543fa11333 upstream. In i915 hwmon sysfs getter path we now take a hwmon_lock, then acquire an rpm wakeref. That results in lock inversion: <4> [197.079335] ====================================================== <4> [197.085473] WARNING: possible circular locking dependency detected <4> [197.091611] 6.8.0-rc7-Patchwork_129026v7-gc4dc92fb1152+ #1 Not tainted <4> [197.098096] ------------------------------------------------------ <4> [197.104231] prometheus-node/839 is trying to acquire lock: <4> [197.109680] ffffffff82764d80 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc+0x9a/0x350 <4> [197.116939] but task is already holding lock: <4> [197.122730] ffff88811b772a40 (&hwmon->hwmon_lock){+.+.}-{3:3}, at: hwm_energy+0x4b/0x100 [i915] <4> [197.131543] which lock already depends on the new lock. ... <4> [197.507922] Chain exists of: fs_reclaim --> >->reset.mutex --> &hwmon->hwmon_lock <4> [197.518528] Possible unsafe locking scenario: <4> [197.524411] CPU0 CPU1 <4> [197.528916] ---- ---- <4> [197.533418] lock(&hwmon->hwmon_lock); <4> [197.537237] lock(>->reset.mutex); <4> [197.543376] lock(&hwmon->hwmon_lock); <4> [197.549682] lock(fs_reclaim); ... <4> [197.632548] Call Trace: <4> [197.634990] <TASK> <4> [197.637088] dump_stack_lvl+0x64/0xb0 <4> [197.640738] check_noncircular+0x15e/0x180 <4> [197.652968] check_prev_add+0xe9/0xce0 <4> [197.656705] __lock_acquire+0x179f/0x2300 <4> [197.660694] lock_acquire+0xd8/0x2d0 <4> [197.673009] fs_reclaim_acquire+0xa1/0xd0 <4> [197.680478] __kmalloc+0x9a/0x350 <4> [197.689063] acpi_ns_internalize_name.part.0+0x4a/0xb0 <4> [197.694170] acpi_ns_get_node_unlocked+0x60/0xf0 <4> [197.720608] acpi_ns_get_node+0x3b/0x60 <4> [197.724428] acpi_get_handle+0x57/0xb0 <4> [197.728164] acpi_has_method+0x20/0x50 <4> [197.731896] acpi_pci_set_power_state+0x43/0x120 <4> [197.736485] pci_power_up+0x24/0x1c0 <4> [197.740047] pci_pm_default_resume_early+0x9/0x30 <4> [197.744725] pci_pm_runtime_resume+0x2d/0x90 <4> [197.753911] __rpm_callback+0x3c/0x110 <4> [197.762586] rpm_callback+0x58/0x70 <4> [197.766064] rpm_resume+0x51e/0x730 <4> [197.769542] rpm_resume+0x267/0x730 <4> [197.773020] rpm_resume+0x267/0x730 <4> [197.776498] rpm_resume+0x267/0x730 <4> [197.779974] __pm_runtime_resume+0x49/0x90 <4> [197.784055] __intel_runtime_pm_get+0x19/0xa0 [i915] <4> [197.789070] hwm_energy+0x55/0x100 [i915] <4> [197.793183] hwm_read+0x9a/0x310 [i915] <4> [197.797124] hwmon_attr_show+0x36/0x120 <4> [197.800946] dev_attr_show+0x15/0x60 <4> [197.804509] sysfs_kf_seq_show+0xb5/0x100 Acquire the wakeref before the lock and hold it as long as the lock is also held. Follow that pattern across the whole source file where similar lock inversion can happen. v2: Keep hardware read under the lock so the whole operation of updating energy from hardware is still atomic (Guenter), - instead, acquire the rpm wakeref before the lock and hold it as long as the lock is held, - use the same aproach for other similar places across the i915_hwmon.c source file (Rodrigo). Fixes: 1b44019a93e2 ("drm/i915/guc: Disable PL1 power limit when loading GuC firmware") Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: <stable@vger.kernel.org> # v6.5+ Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com> Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20240311203500.518675-2-janusz.krzysztofik@linux.intel.com (cherry picked from commit 71b218771426ea84c0e0148a2b7ac52c1f76e792) Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.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.