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Serge Semin 574f69b46b mips: Fix max_mapnr being uninitialized on early stages 
commit e1a9ae4573 upstream.

max_mapnr variable is utilized in the pfn_valid() method in order to
determine the upper PFN space boundary. Having it uninitialized
effectively makes any PFN passed to that method invalid. That in its turn
causes the kernel mm-subsystem occasion malfunctions even after the
max_mapnr variable is actually properly updated. For instance,
pfn_valid() is called in the init_unavailable_range() method in the
framework of the calls-chain on MIPS:
setup_arch()
+-> paging_init()
    +-> free_area_init()
        +-> memmap_init()
            +-> memmap_init_zone_range()
                +-> init_unavailable_range()

Since pfn_valid() always returns "false" value before max_mapnr is
initialized in the mem_init() method, any flatmem page-holes will be left
in the poisoned/uninitialized state including the IO-memory pages. Thus
any further attempts to map/remap the IO-memory by using MMU may fail.
In particular it happened in my case on attempt to map the SRAM region.
The kernel bootup procedure just crashed on the unhandled unaligned access
bug raised in the __update_cache() method:

> Unhandled kernel unaligned access[#1]:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.7.0-rc1-XXX-dirty #2056
> ...
> Call Trace:
> [<8011ef9c>] __update_cache+0x88/0x1bc
> [<80385944>] ioremap_page_range+0x110/0x2a4
> [<80126948>] ioremap_prot+0x17c/0x1f4
> [<80711b80>] __devm_ioremap+0x8c/0x120
> [<80711e0c>] __devm_ioremap_resource+0xf4/0x218
> [<808bf244>] sram_probe+0x4f4/0x930
> [<80889d20>] platform_probe+0x68/0xec
> ...

Let's fix the problem by initializing the max_mapnr variable as soon as
the required data is available. In particular it can be done right in the
paging_init() method before free_area_init() is called since all the PFN
zone boundaries have already been calculated by that time.

Cc: stable@vger.kernel.org
Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2024-01-31 16:16:59 -08:00
arch mips: Fix max_mapnr being uninitialized on early stages 2024-01-31 16:16:59 -08:00
block block: Remove special-casing of compound pages 2024-01-25 15:27:52 -08:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: api - Disallow identical driver names 2024-01-31 16:16:58 -08:00
Documentation PM / devfreq: Fix buffer overflow in trans_stat_show 2024-01-31 16:16:58 -08:00
drivers s390/vfio-ap: let on_scan_complete() callback filter matrix and update guest's APCB 2024-01-31 16:16:59 -08:00
fs btrfs: sysfs: validate scrub_speed_max value 2024-01-31 16:16:58 -08:00
include netfilter: bridge: replace physindev with physinif in nf_bridge_info 2024-01-25 15:27:51 -08:00
init rootfs: Fix support for rootfstype= when root= is given 2024-01-25 15:27:43 -08:00
io_uring io_uring/rw: ensure io->bytes_done is always initialized 2024-01-25 15:27:41 -08:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel PM: hibernate: Enforce ordering during image compression/decompression 2024-01-31 16:16:58 -08:00
lib kunit: debugfs: Fix unchecked dereference in debugfs_print_results() 2024-01-25 15:27:21 -08:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: fix unmap_mapping_range high bits shift bug 2024-01-10 17:10:35 +01:00
net ipv6: mcast: fix data-race in ipv6_mc_down / mld_ifc_work 2024-01-25 15:27:51 -08:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples fprobe: Pass entry_data to handlers 2023-10-25 12:03:12 +02:00
scripts powerpc: remove checks for binutils older than 2.25 2024-01-25 15:27:18 -08:00
security Revert "KEYS: encrypted: Add check for strsep" 2024-01-25 15:27:52 -08:00
sound ASoC: mediatek: sof-common: Add NULL check for normal_link string 2024-01-25 15:27:48 -08:00
tools selftests: mlxsw: qos_pfc: Adjust the test to support 8 lanes 2024-01-25 15:27:51 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:42:46 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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 dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -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 MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
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 genirq/affinity: Move group_cpus_evenly() into lib/ 2024-01-10 17:10:33 +01:00
Makefile Linux 6.1.75 2024-01-25 15:27:52 -08:00
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.