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Sudeep Holla 91d7b60a65 ACPI: PPTT: Fix to avoid sleep in the atomic context when PPTT is absent 
Commit 0c80f9e165 ("ACPI: PPTT: Leave the table mapped for the runtime usage")
enabled to map PPTT once on the first invocation of acpi_get_pptt() and
never unmapped the same allowing it to be used at runtime with out the
hassle of mapping and unmapping the table. This was needed to fetch LLC
information from the PPTT in the cpuhotplug path which is executed in
the atomic context as the acpi_get_table() might sleep waiting for a
mutex.

However it missed to handle the case when there is no PPTT on the system
which results in acpi_get_pptt() being called from all the secondary
CPUs attempting to fetch the LLC information in the atomic context
without knowing the absence of PPTT resulting in the splat like below:

 | BUG: sleeping function called from invalid context at kernel/locking/semaphore.c:164
 | in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/1
 | preempt_count: 1, expected: 0
 | RCU nest depth: 0, expected: 0
 | no locks held by swapper/1/0.
 | irq event stamp: 0
 | hardirqs last  enabled at (0): 0x0
 | hardirqs last disabled at (0): copy_process+0x61c/0x1b40
 | softirqs last  enabled at (0): copy_process+0x61c/0x1b40
 | softirqs last disabled at (0): 0x0
 | CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.3.0-rc1 #1
 | Call trace:
 |  dump_backtrace+0xac/0x138
 |  show_stack+0x30/0x48
 |  dump_stack_lvl+0x60/0xb0
 |  dump_stack+0x18/0x28
 |  __might_resched+0x160/0x270
 |  __might_sleep+0x58/0xb0
 |  down_timeout+0x34/0x98
 |  acpi_os_wait_semaphore+0x7c/0xc0
 |  acpi_ut_acquire_mutex+0x58/0x108
 |  acpi_get_table+0x40/0xe8
 |  acpi_get_pptt+0x48/0xa0
 |  acpi_get_cache_info+0x38/0x140
 |  init_cache_level+0xf4/0x118
 |  detect_cache_attributes+0x2e4/0x640
 |  update_siblings_masks+0x3c/0x330
 |  store_cpu_topology+0x88/0xf0
 |  secondary_start_kernel+0xd0/0x168
 |  __secondary_switched+0xb8/0xc0

Update acpi_get_pptt() to consider the fact that PPTT is once checked and
is not available on the system and return NULL avoiding any attempts to
fetch PPTT and thereby avoiding any possible sleep waiting for a mutex
in the atomic context.

Fixes: 0c80f9e165 ("ACPI: PPTT: Leave the table mapped for the runtime usage")
Reported-by: Aishwarya TCV <aishwarya.tcv@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Pierre Gondois <pierre.gondois@arm.com>
Cc: 6.0+ <stable@vger.kernel.org> # 6.0+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2023-03-14 20:34:38 +01:00
arch - Disable XSAVES on AMD Zen1 and Zen2 machines due to an erratum. No 2023-03-12 09:12:03 -07:00
block block, bfq: fix uaf for 'stable_merge_bfqq' 2023-03-08 07:34:50 -07:00
certs Kbuild updates for v6.3 2023-02-26 11:53:25 -08:00
crypto Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
Documentation Bug fixes and regressions for ext4, the most serious of which is a 2023-03-12 08:55:55 -07:00
drivers ACPI: PPTT: Fix to avoid sleep in the atomic context when PPTT is absent 2023-03-14 20:34:38 +01:00
fs Fixes for 6.3-rc1: 2023-03-12 09:47:08 -07:00
include Bug fixes and regressions for ext4, the most serious of which is a 2023-03-12 08:55:55 -07:00
init Kbuild updates for v6.3 2023-02-26 11:53:25 -08:00
io_uring io_uring: silence variable ‘prev’ set but not used warning 2023-03-09 10:10:58 -07:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel kernel.fork.v6.3-rc2 2023-03-12 09:04:28 -07:00
lib cpumask: re-introduce constant-sized cpumask optimizations 2023-03-05 14:30:34 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: avoid gcc complaint about pointer casting 2023-03-04 14:03:27 -08:00
net wifi: cfg80211: Partial revert "wifi: cfg80211: Fix use after free for wext" 2023-03-12 16:21:59 -07:00
rust Rust fixes for 6.3-rc1 2023-03-03 14:51:15 -08:00
samples LoongArch changes for v6.3 2023-03-01 09:27:00 -08:00
scripts Remove Intel compiler support 2023-03-05 10:49:37 -08:00
security capability: just use a 'u64' instead of a 'u32[2]' array 2023-03-01 10:01:22 -08:00
sound sound fixes for 6.3-rc1 2023-03-04 10:53:59 -08:00
tools kernel.fork.v6.3-rc2 2023-03-12 09:04:28 -07:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM/riscv changes for 6.3 2023-02-15 12:33:28 -05:00
.clang-format cpumask: re-introduce constant-sized cpumask optimizations 2023-03-05 14:30:34 -08:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore .gitignore: ignore *.cover and *.mbx 2023-02-05 18:51:22 +09:00
.mailmap drm fixes for 6.3-rc2 2023-03-10 08:57:46 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS There is no particular theme here - mainly quick hits all over the tree. 2023-02-23 17:55:40 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Staging driver fixes and removal for 6.3-rc2 2023-03-12 09:17:30 -07:00
Makefile Linux 6.3-rc2 2023-03-12 16:36:44 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.