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Simon SchusterandGreg Kroah-Hartman
b1ec9faef7
[ Upstream commit a20b83cf45 ]
On nios2, with CONFIG_FLATMEM set, the kernel relies on
memblock_get_current_limit() to determine the limits of mem_map, in
particular for max_low_pfn.
Unfortunately, memblock.current_limit is only default initialized to
MEMBLOCK_ALLOC_ANYWHERE at this point of the bootup, potentially leading
to situations where max_low_pfn can erroneously exceed the value of
max_pfn and, thus, the valid range of available DRAM.
This can in turn cause kernel-level paging failures, e.g.:
[ 76.900000] Unable to handle kernel paging request at virtual address 20303000
[ 76.900000] ea = c0080890, ra = c000462c, cause = 14
[ 76.900000] Kernel panic - not syncing: Oops
[ 76.900000] ---[ end Kernel panic - not syncing: Oops ]---
This patch fixes this by pre-calculating memblock.current_limit
based on the upper limits of the available memory ranges via
adjust_lowmem_bounds, a simplified version of the equivalent
implementation within the arm architecture.
Signed-off-by: Simon Schuster <schuster.simon@siemens-energy.com>
Signed-off-by: Andreas Oetken <andreas.oetken@siemens-energy.com>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.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.