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Heiko Carstens 536d7fa7fb s390/smp: fix physical to logical CPU map for SMT
[ Upstream commit 72a81ad9d6d62dcb79f7e8ad66ffd1c768b72026 ]

If an SMT capable system is not IPL'ed from the first CPU the setup of
the physical to logical CPU mapping is broken: the IPL core gets CPU
number 0, but then the next core gets CPU number 1. Correct would be
that all SMT threads of CPU 0 get the subsequent logical CPU numbers.

This is important since a lot of code (like e.g. the CPU topology
code) assumes that CPU maps are setup like this. If the mapping is
broken the system will not IPL due to broken topology masks:

[    1.716341] BUG: arch topology broken
[    1.716342]      the SMT domain not a subset of the MC domain
[    1.716343] BUG: arch topology broken
[    1.716344]      the MC domain not a subset of the BOOK domain

This scenario can usually not happen since LPARs are always IPL'ed
from CPU 0 and also re-IPL is intiated from CPU 0. However older
kernels did initiate re-IPL on an arbitrary CPU. If therefore a re-IPL
from an old kernel into a new kernel is initiated this may lead to
crash.

Fix this by setting up the physical to logical CPU mapping correctly.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-01-09 10:20:06 +01:00
arch s390/smp: fix physical to logical CPU map for SMT 2020-01-09 10:20:06 +01:00
block
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Documentation dt-bindings: clock: renesas: rcar-usb2-clock-sel: Fix typo in example 2020-01-09 10:20:05 +01:00
drivers net: add annotations on hh->hh_len lockless accesses 2020-01-09 10:20:06 +01:00
fs Btrfs: only associate the locked page with one async_chunk struct 2020-01-09 10:20:06 +01:00
include net: add annotations on hh->hh_len lockless accesses 2020-01-09 10:20:06 +01:00
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kernel kernel/module.c: wakeup processes in module_wq on module unload 2020-01-09 10:20:02 +01:00
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net net: add annotations on hh->hh_len lockless accesses 2020-01-09 10:20:06 +01:00
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tools perf callchain: Fix segfault in thread__resolve_callchain_sample() 2020-01-09 10:20:02 +01:00
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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.