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Lars Persson f70ddae24b mm/migrate.c: add missing flush_dcache_page for non-mapped page migrate commit `d2b2c6dd22` upstream. Our MIPS 1004Kc SoCs were seeing random userspace crashes with SIGILL and SIGSEGV that could not be traced back to a userspace code bug. They had all the magic signs of an I/D cache coherency issue. Now recently we noticed that the /proc/sys/vm/compact_memory interface was quite efficient at provoking this class of userspace crashes. Studying the code in mm/migrate.c there is a distinction made between migrating a page that is mapped at the instant of migration and one that is not mapped. Our problem turned out to be the non-mapped pages. For the non-mapped page the code performs a copy of the page content and all relevant meta-data of the page without doing the required D-cache maintenance. This leaves dirty data in the D-cache of the CPU and on the 1004K cores this data is not visible to the I-cache. A subsequent page-fault that triggers a mapping of the page will happily serve the process with potentially stale code. What about ARM then, this bug should have seen greater exposure? Well ARM became immune to this flaw back in 2010, see commit `c01778001a` ("ARM: 6379/1: Assume new page cache pages have dirty D-cache"). My proposed fix moves the D-cache maintenance inside move_to_new_page to make it common for both cases. Link: http://lkml.kernel.org/r/20190315083502.11849-1-larper@axis.com Fixes: `97ee052461` ("flush cache before installing new page at migraton") Signed-off-by: Lars Persson <larper@axis.com> Reviewed-by: Paul Burton <paul.burton@mips.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2019-04-03 06:26:28 +02:00
arch	powerpc: bpf: Fix generation of load/store DW instructions	2019-04-03 06:26:21 +02:00
block	blk-mq: insert rq with DONTPREP to hctx dispatch list when requeue	2019-03-23 20:09:45 +01:00
certs	export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR()	2018-08-22 23:21:44 +09:00
crypto	crypto: testmgr - skip crc32c context test for ahash algorithms	2019-03-23 20:09:55 +01:00
Documentation	stable-kernel-rules.rst: add link to networking patch queue	2019-03-23 20:10:10 +01:00
drivers	iommu/io-pgtable-arm-v7s: request DMA32 memory, and improve debugging	2019-04-03 06:26:28 +02:00
firmware	kbuild: remove all dummy assignments to obj-	2017-11-18 11:46:06 +09:00
fs	fs/proc/proc_sysctl.c: fix NULL pointer dereference in put_links	2019-04-03 06:26:26 +02:00
include	mm: add support for kmem caches in DMA32 zone	2019-04-03 06:26:28 +02:00
init	Revert "mm: use early_pfn_to_nid in page_ext_init"	2019-03-23 20:09:46 +01:00
ipc	ipc/shm.c: use ERR_CAST() for shm_lock() error return	2018-10-05 16:32:04 -07:00
kernel	locking/lockdep: Add debug_locks check in __lock_downgrade()	2019-03-27 14:14:43 +09:00
lib	rhashtable: Still do rehash when we get EEXIST	2019-04-03 06:26:17 +02:00
LICENSES	LICENSES: Remove CC-BY-SA-4.0 license text	2018-10-18 11:28:50 +02:00
mm	mm/migrate.c: add missing flush_dcache_page for non-mapped page migrate	2019-04-03 06:26:28 +02:00
net	net: sched: fix cleanup NULL pointer exception in act_mirr	2019-04-03 06:26:19 +02:00
samples	samples: mei: use /dev/mei0 instead of /dev/mei	2019-02-15 08:10:11 +01:00
scripts	kbuild: modversions: Fix relative CRC byte order interpretation	2019-04-03 06:26:23 +02:00
security	security/selinux: fix SECURITY_LSM_NATIVE_LABELS on reused superblock	2019-03-23 20:10:06 +01:00
sound	ALSA: hda/realtek - Fix speakers on Acer Predator Helios 500 Ryzen laptops	2019-04-03 06:26:23 +02:00
tools	objtool: Move objtool_file struct off the stack	2019-03-27 14:14:40 +09:00
usr	initramfs: move gen_initramfs_list.sh from scripts/ to usr/	2018-08-22 23:21:44 +09:00
virt	KVM: Call kvm_arch_memslots_updated() before updating memslots	2019-03-23 20:10:13 +01:00
.clang-format	clang-format: Set IndentWrappedFunctionNames false	2018-08-01 18:38:51 +02:00
.cocciconfig	scripts: add Linux .cocciconfig for coccinelle	2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes	.gitattributes: set git diff driver for C source code files	2016-10-07 18:46:30 -07:00
.gitignore	Kbuild updates for v4.17 (2nd)	2018-04-15 17:21:30 -07:00
.mailmap	libnvdimm-for-4.19_misc	2018-08-25 18:13:10 -07:00
COPYING	COPYING: use the new text with points to the license files	2018-03-23 12:41:45 -06:00
CREDITS	9p: remove Ron Minnich from MAINTAINERS	2018-08-17 16:20:26 -07:00
Kbuild	Kbuild updates for v4.15	2017-11-17 17:45:29 -08:00
Kconfig	kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt	2018-08-02 08:06:55 +09:00
MAINTAINERS	MAINTAINERS: Add Sasha as a stable branch maintainer	2018-12-01 09:37:25 +01:00
Makefile	Linux 4.19.32	2019-03-27 14:14:43 +09:00
README	Docs: Added a pointer to the formatted docs to README	2018-03-21 09:02:53 -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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.