forked from Minki/linux
mainlining shenanigans
40a899ed16
In https://lkml.org/lkml/2017/11/20/411, Andrea reported that during
memory hotplug/hot remove prep_transhuge_page() is called incorrectly on
non-THP pages for migration, when THP is on but THP migration is not
enabled. This leads to a bad state of target pages for migration.
By inspecting the code, if called on a non-THP, prep_transhuge_page()
will
1) change the value of the mapping of (page + 2), since it is used for
THP deferred list;
2) change the lru value of (page + 1), since it is used for THP's dtor.
Both can lead to data corruption of these two pages.
Andrea said:
"Pragmatically and from the point of view of the memory_hotplug subsys,
the effect is a kernel crash when pages are being migrated during a
memory hot remove offline and migration target pages are found in a
bad state"
This patch fixes it by only calling prep_transhuge_page() when we are
certain that the target page is THP.
Link: http://lkml.kernel.org/r/20171121021855.50525-1-zi.yan@sent.com
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.