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Stephen Boyd da17d6905d of/fdt: Don't worry about non-memory region overlap for no-map
In commit 8a5a75e5e9 ("of/fdt: Make sure no-map does not remove
already reserved regions") we returned -EBUSY when trying to mark
regions as no-map when they intersect with reserved memory. The goal was
to find bad no-map reserved memory DT nodes that would unmap the kernel
text/data sections.

The problem is the reserved memory check will still trigger if the DT
has a /memreserve/ that completely subsumes the no-map memory carveouts
in the reserved memory node _and_ that region is also not part of the
memory reg property. For example in sc7180.dtsi we have the following
reserved-memory and memory node:

      memory@80000000 {
          /* We expect the bootloader to fill in the size */
          reg = <0 0x80000000 0 0>;
      };

      smem_mem: memory@80900000 {
              reg = <0x0 0x80900000 0x0 0x200000>;
              no-map;
      };

and the memreserve filled in by the bootloader is

      /memreserve/ 0x80800000 0x400000;

while the /memory node is transformed into

      memory@80000000 {
          /* The bootloader fills in the size, and adds another region */
          reg = <0 0x80000000 0 0x00800000>,
                <0 0x80c00000 0 0x7f200000>;
      };

The smem region is doubly reserved via /memreserve/ and by not being
part of the /memory reg property. This leads to the following warning
printed at boot.

 OF: fdt: Reserved memory: failed to reserve memory for node 'memory@80900000': base 0x0000000080900000, size 2 MiB

Otherwise nothing really goes wrong because the smem region is not going
to be mapped by the kernel's direct linear mapping given that it isn't
part of the memory node. Therefore, let's only consider this to be a
problem if we're trying to mark a region as no-map and it is actually
memory that we're intending to keep out of the kernel's direct mapping
but it's already been reserved.

Acked-by: Mike Rapoport <rppt@kernel.org>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Nicolas Boichat <drinkcat@chromium.org>
Cc: Quentin Perret <qperret@google.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Fixes: 8a5a75e5e9 ("of/fdt: Make sure no-map does not remove already reserved regions")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220107194233.2793146-1-swboyd@chromium.org
2022-01-08 08:50:39 -06:00
arch of/fdt: Rework early_init_dt_scan_memory() to call directly 2021-12-16 16:07:52 -06:00
block blk-mq: fix filesystem I/O request allocation 2021-11-12 09:31:13 -07:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
Documentation dt-bindings: display: novatek,nt36672a: Fix unevaluated properties warning 2022-01-05 11:42:33 -06:00
drivers of/fdt: Don't worry about non-memory region overlap for no-map 2022-01-08 08:50:39 -06:00
fs Minor tweaks for 5.16: 2021-11-14 12:18:22 -08:00
include of/fdt: Rework early_init_dt_scan_memory() to call directly 2021-12-16 16:07:52 -06:00
init kconfig: Add support for -Wimplicit-fallthrough 2021-11-14 13:27:30 -08:00
ipc ipc/ipc_sysctl.c: remove fallback for !CONFIG_PROC_SYSCTL 2021-11-09 10:02:53 -08:00
kernel A single fix for POSIX CPU timers to address a problem where POSIX CPU 2021-11-14 10:43:38 -08:00
lib Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm Revert "mm: shmem: don't truncate page if memory failure happens" 2021-11-13 12:03:03 -08:00
net One notable change here is that async creates and unlinks introduced 2021-11-13 11:31:07 -08:00
samples Add gitignore file for samples/fanotify/ subdirectory 2021-11-07 11:19:24 -08:00
scripts coccinelle patches for 5.16-rc1 2021-11-13 10:45:17 -08:00
security net,lsm,selinux: revert the security_sctp_assoc_established() hook 2021-11-12 12:07:02 -05:00
sound sound fixes for 5.16-rc1 2021-11-12 12:17:30 -08:00
tools A single fix for static calls to make the trampoline patching more robust 2021-11-14 10:30:17 -08:00
usr initramfs: Check timestamp to prevent broken cpio archive 2021-10-24 13:48:40 +09:00
virt KVM: generalize "bugged" VM to "dead" VM 2021-11-11 10:35:26 -05:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap Merge branch 'akpm' (patches from Andrew) 2021-11-09 10:11:53 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS dt-bindings: usb: Convert BDC to YAML 2021-12-17 09:05:07 -06:00
Makefile Linux 5.16-rc1 2021-11-14 13:56:52 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.