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2613cc29c5
fw_token is used for DT/ACPI systems to identify CPUs sharing caches.
For DT based systems, fw_token is set to a pointer to a DT node.
commit 3da72e18371c ("cacheinfo: Decrement refcount in
cache_setup_of_node()")
doesn't increment the refcount of fw_token anymore in
cache_setup_of_node(). fw_token is indeed used as a token and not
as a (struct device_node*), so no reference to fw_token should be
kept.
However, [1] is triggered when hotplugging a CPU multiple times
since cache_shared_cpu_map_remove() decrements the refcount to
fw_token at each CPU unplugging, eventually reaching 0.
Remove of_node_put() for fw_token in cache_shared_cpu_map_remove().
[1]
------------[ cut here ]------------
refcount_t: saturated; leaking memory.
WARNING: CPU: 4 PID: 32 at lib/refcount.c:22 refcount_warn_saturate (lib/refcount.c:22 (discriminator 3))
Modules linked in:
CPU: 4 PID: 32 Comm: cpuhp/4 Tainted: G W 6.1.0-rc1-14091-g9fdf2ca7b9c8 #76
Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Oct 31 2022
pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : refcount_warn_saturate (lib/refcount.c:22 (discriminator 3))
lr : refcount_warn_saturate (lib/refcount.c:22 (discriminator 3))
[...]
Call trace:
[...]
of_node_release (drivers/of/dynamic.c:335)
kobject_put (lib/kobject.c:677 lib/kobject.c:704 ./include/linux/kref.h:65 lib/kobject.c:721)
of_node_put (drivers/of/dynamic.c:49)
free_cache_attributes.part.0 (drivers/base/cacheinfo.c:712)
cacheinfo_cpu_pre_down (drivers/base/cacheinfo.c:718)
cpuhp_invoke_callback (kernel/cpu.c:247 (discriminator 4))
cpuhp_thread_fun (kernel/cpu.c:785)
smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3))
kthread (kernel/kthread.c:376)
ret_from_fork (arch/arm64/kernel/entry.S:861)
---[ end trace 0000000000000000 ]---
Fixes: 3da72e18371c ("cacheinfo: Decrement refcount in cache_setup_of_node()")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Link: https://lore.kernel.org/r/20221116094958.2141072-1-pierre.gondois@arm.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.