Revision 8a8683ad9ba48b4b52a57f013513d1635c1ca5c4 authored by Huang Ying on 06 March 2020, 06:28:29 UTC, committed by Linus Torvalds on 06 March 2020, 13:06:09 UTC
In set_pmd_migration_entry(), pmdp_invalidate() is used to change PMD atomically. But the PMD is read before that with an ordinary memory reading. If the THP (transparent huge page) is written between the PMD reading and pmdp_invalidate(), the PMD dirty bit may be lost, and cause data corruption. The race window is quite small, but still possible in theory, so need to be fixed. The race is fixed via using the return value of pmdp_invalidate() to get the original content of PMD, which is a read/modify/write atomic operation. So no THP writing can occur in between. The race has been introduced when the THP migration support is added in the commit 616b8371539a ("mm: thp: enable thp migration in generic path"). But this fix depends on the commit d52605d7cb30 ("mm: do not lose dirty and accessed bits in pmdp_invalidate()"). So it's easy to be backported after v4.16. But the race window is really small, so it may be fine not to backport the fix at all. Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: <stable@vger.kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Link: http://lkml.kernel.org/r/20200220075220.2327056-1-ying.huang@intel.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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index.rst
.. The Linux Kernel documentation master file, created by
sphinx-quickstart on Fri Feb 12 13:51:46 2016.
You can adapt this file completely to your liking, but it should at least
contain the root `toctree` directive.
.. _linux_doc:
The Linux Kernel documentation
==============================
This is the top level of the kernel's documentation tree. Kernel
documentation, like the kernel itself, is very much a work in progress;
that is especially true as we work to integrate our many scattered
documents into a coherent whole. Please note that improvements to the
documentation are welcome; join the linux-doc list at vger.kernel.org if
you want to help out.
Licensing documentation
-----------------------
The following describes the license of the Linux kernel source code
(GPLv2), how to properly mark the license of individual files in the source
tree, as well as links to the full license text.
* :ref:`kernel_licensing`
User-oriented documentation
---------------------------
The following manuals are written for *users* of the kernel — those who are
trying to get it to work optimally on a given system.
.. toctree::
:maxdepth: 2
admin-guide/index
kbuild/index
Firmware-related documentation
------------------------------
The following holds information on the kernel's expectations regarding the
platform firmwares.
.. toctree::
:maxdepth: 2
firmware-guide/index
Application-developer documentation
-----------------------------------
The user-space API manual gathers together documents describing aspects of
the kernel interface as seen by application developers.
.. toctree::
:maxdepth: 2
userspace-api/index
Introduction to kernel development
----------------------------------
These manuals contain overall information about how to develop the kernel.
The kernel community is quite large, with thousands of developers
contributing over the course of a year. As with any large community,
knowing how things are done will make the process of getting your changes
merged much easier.
.. toctree::
:maxdepth: 2
process/index
dev-tools/index
doc-guide/index
kernel-hacking/index
trace/index
maintainer/index
fault-injection/index
livepatch/index
Kernel API documentation
------------------------
These books get into the details of how specific kernel subsystems work
from the point of view of a kernel developer. Much of the information here
is taken directly from the kernel source, with supplemental material added
as needed (or at least as we managed to add it — probably *not* all that is
needed).
.. toctree::
:maxdepth: 2
driver-api/index
core-api/index
locking/index
accounting/index
block/index
cdrom/index
ide/index
fb/index
fpga/index
hid/index
i2c/index
iio/index
isdn/index
infiniband/index
leds/index
media/index
netlabel/index
networking/index
pcmcia/index
power/index
target/index
timers/index
spi/index
w1/index
watchdog/index
virt/index
input/index
hwmon/index
gpu/index
security/index
sound/index
crypto/index
filesystems/index
vm/index
bpf/index
usb/index
PCI/index
misc-devices/index
mic/index
scheduler/index
Architecture-agnostic documentation
-----------------------------------
.. toctree::
:maxdepth: 2
asm-annotations
Architecture-specific documentation
-----------------------------------
These books provide programming details about architecture-specific
implementation.
.. toctree::
:maxdepth: 2
arm/index
arm64/index
ia64/index
m68k/index
mips/index
nios2/nios2
openrisc/index
parisc/index
powerpc/index
riscv/index
s390/index
sh/index
sparc/index
x86/index
xtensa/index
Filesystem Documentation
------------------------
The documentation in this section are provided by specific filesystem
subprojects.
.. toctree::
:maxdepth: 2
filesystems/ext4/index
Translations
------------
.. toctree::
:maxdepth: 2
translations/index
Indices and tables
==================
* :ref:`genindex`
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