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dca4436d1c
On PowerPC, the address ranges allocated to OpenCAPI LPC memory are
allocated from firmware. These address ranges may be higher than what
older kernels permit, as we increased the maximum permissable address in
commit 4ffe713b75 ("powerpc/mm: Increase the max addressable memory to
2PB"). It is possible that the addressable range may change again in
the future.
In this scenario, we end up with a bogus section returned from
__section_nr (see the discussion on the thread "mm: Trigger bug on if a
section is not found in __section_nr").
Adding a check here means that we fail early and have an opportunity to
handle the error gracefully, rather than rumbling on and potentially
accessing an incorrect section.
Further discussion is also on the thread ("powerpc: Perform a bounds
check in arch_add_memory")
http://lkml.kernel.org/r/20190827052047.31547-1-alastair@au1.ibm.com
Link: http://lkml.kernel.org/r/20191001004617.7536-2-alastair@au1.ibm.com
Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.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.