The source for the Linux kernel used in Windows Subsystem for Linux 2 (WSL2)
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Borislav Petkov 3bff147b18 x86/mce: Defer processing of early errors
When a fatal machine check results in a system reset, Linux does not
clear the error(s) from machine check bank(s) - hardware preserves the
machine check banks across a warm reset.

During initialization of the kernel after the reboot, Linux reads, logs,
and clears all machine check banks.

But there is a problem. In:

  5de97c9f6d ("x86/mce: Factor out and deprecate the /dev/mcelog driver")

the call to mce_register_decode_chain() moved later in the boot
sequence. This means that /dev/mcelog doesn't see those early error
logs.

This was partially fixed by:

  cd9c57cad3 ("x86/MCE: Dump MCE to dmesg if no consumers")

which made sure that the logs were not lost completely by printing
to the console. But parsing console logs is error prone. Users of
/dev/mcelog should expect to find any early errors logged to standard
places.

Add a new flag MCP_QUEUE_LOG to machine_check_poll() to be used in early
machine check initialization to indicate that any errors found should
just be queued to genpool. When mcheck_late_init() is called it will
call mce_schedule_work() to actually log and flush any errors queued in
the genpool.

 [ Based on an original patch, commit message by and completely
   productized by Tony Luck. ]

Fixes: 5de97c9f6d ("x86/mce: Factor out and deprecate the /dev/mcelog driver")
Reported-by: Sumanth Kamatala <skamatala@juniper.net>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210824003129.GA1642753@agluck-desk2.amr.corp.intel.com
2021-08-24 10:40:58 +02:00
Documentation RISC-V Fixes for 5.14-rc7 2021-08-21 11:04:26 -07:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
arch x86/mce: Defer processing of early errors 2021-08-24 10:40:58 +02:00
block block-5.14-2021-08-20 2021-08-21 08:11:22 -07:00
certs Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
crypto crypto: drbg - select SHA512 2021-07-16 15:49:31 +08:00
drivers Two clk driver fixes 2021-08-21 11:27:16 -07:00
fs File locking change for v5.14 2021-08-21 10:50:22 -07:00
include Merge branch 'akpm' (patches from Andrew) 2021-08-20 13:08:56 -07:00
init init: Suppress wrong warning for bootconfig cmdline parameter 2021-08-12 13:35:57 -04:00
ipc Merge branch 'akpm' (patches from Andrew) 2021-07-02 12:08:10 -07:00
kernel Networking fixes for 5.14-rc7, including fixes from bpf, wireless and 2021-08-19 12:33:43 -07:00
lib lib: use PFN_PHYS() in devmem_is_allowed() 2021-08-13 14:09:32 -10:00
mm hugetlb: don't pass page cache pages to restore_reserve_on_error 2021-08-20 11:31:42 -07:00
net mptcp: full fully established support after ADD_ADDR 2021-08-19 12:16:54 +01:00
samples Networking fixes for 5.14-rc2, including fixes from bpf and netfilter. 2021-07-14 09:24:32 -07:00
scripts Kbuild fixes for v5.14 (2nd) 2021-08-07 10:03:02 -07:00
security bpf: Add lockdown check for probe_write_user helper 2021-08-10 10:10:10 +02:00
sound another sound-fixes for 5.14-rc7 2021-08-20 12:31:10 -07:00
tools Networking fixes for 5.14-rc7, including fixes from bpf, wireless and 2021-08-19 12:33:43 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Do not leak memory for duplicate debugfs directories 2021-08-04 06:02:03 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.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 m68k updates for v5.14 2021-06-28 14:01:03 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
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 Merge branch 'akpm' (patches from Andrew) 2021-08-20 13:08:56 -07:00
Makefile Linux 5.14-rc7 2021-08-22 14:24:56 -07:00
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.