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>
1 parent 8b272b3
Raw File
Makefile
# -*- makefile -*-
# Makefile for Sphinx documentation
#

subdir-y := devicetree/bindings/

# Check for broken documentation file references
ifeq ($(CONFIG_WARN_MISSING_DOCUMENTS),y)
$(shell $(srctree)/scripts/documentation-file-ref-check --warn)
endif

# You can set these variables from the command line.
SPHINXBUILD   = sphinx-build
SPHINXOPTS    =
SPHINXDIRS    = .
_SPHINXDIRS   = $(patsubst $(srctree)/Documentation/%/index.rst,%,$(wildcard $(srctree)/Documentation/*/index.rst))
SPHINX_CONF   = conf.py
PAPER         =
BUILDDIR      = $(obj)/output
PDFLATEX      = xelatex
LATEXOPTS     = -interaction=batchmode

# User-friendly check for sphinx-build
HAVE_SPHINX := $(shell if which $(SPHINXBUILD) >/dev/null 2>&1; then echo 1; else echo 0; fi)

ifeq ($(HAVE_SPHINX),0)

.DEFAULT:
	$(warning The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed and in PATH, or set the SPHINXBUILD make variable to point to the full path of the '$(SPHINXBUILD)' executable.)
	@echo
	@$(srctree)/scripts/sphinx-pre-install
	@echo "  SKIP    Sphinx $@ target."

else # HAVE_SPHINX

# User-friendly check for pdflatex and latexmk
HAVE_PDFLATEX := $(shell if which $(PDFLATEX) >/dev/null 2>&1; then echo 1; else echo 0; fi)
HAVE_LATEXMK := $(shell if which latexmk >/dev/null 2>&1; then echo 1; else echo 0; fi)

ifeq ($(HAVE_LATEXMK),1)
	PDFLATEX := latexmk -$(PDFLATEX)
endif #HAVE_LATEXMK

# Internal variables.
PAPEROPT_a4     = -D latex_paper_size=a4
PAPEROPT_letter = -D latex_paper_size=letter
KERNELDOC       = $(srctree)/scripts/kernel-doc
KERNELDOC_CONF  = -D kerneldoc_srctree=$(srctree) -D kerneldoc_bin=$(KERNELDOC)
ALLSPHINXOPTS   =  $(KERNELDOC_CONF) $(PAPEROPT_$(PAPER)) $(SPHINXOPTS)
# the i18n builder cannot share the environment and doctrees with the others
I18NSPHINXOPTS  = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .

# commands; the 'cmd' from scripts/Kbuild.include is not *loopable*
loop_cmd = $(echo-cmd) $(cmd_$(1)) || exit;

# $2 sphinx builder e.g. "html"
# $3 name of the build subfolder / e.g. "media", used as:
#    * dest folder relative to $(BUILDDIR) and
#    * cache folder relative to $(BUILDDIR)/.doctrees
# $4 dest subfolder e.g. "man" for man pages at media/man
# $5 reST source folder relative to $(srctree)/$(src),
#    e.g. "media" for the linux-tv book-set at ./Documentation/media

quiet_cmd_sphinx = SPHINX  $@ --> file://$(abspath $(BUILDDIR)/$3/$4)
      cmd_sphinx = $(MAKE) BUILDDIR=$(abspath $(BUILDDIR)) $(build)=Documentation/media $2 && \
	PYTHONDONTWRITEBYTECODE=1 \
	BUILDDIR=$(abspath $(BUILDDIR)) SPHINX_CONF=$(abspath $(srctree)/$(src)/$5/$(SPHINX_CONF)) \
	$(PYTHON) $(srctree)/scripts/jobserver-exec \
	$(SHELL) $(srctree)/Documentation/sphinx/parallel-wrapper.sh \
	$(SPHINXBUILD) \
	-b $2 \
	-c $(abspath $(srctree)/$(src)) \
	-d $(abspath $(BUILDDIR)/.doctrees/$3) \
	-D version=$(KERNELVERSION) -D release=$(KERNELRELEASE) \
	$(ALLSPHINXOPTS) \
	$(abspath $(srctree)/$(src)/$5) \
	$(abspath $(BUILDDIR)/$3/$4)

htmldocs:
	@$(srctree)/scripts/sphinx-pre-install --version-check
	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,html,$(var),,$(var)))

linkcheckdocs:
	@$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,linkcheck,$(var),,$(var)))

latexdocs:
	@$(srctree)/scripts/sphinx-pre-install --version-check
	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,latex,$(var),latex,$(var)))

ifeq ($(HAVE_PDFLATEX),0)

pdfdocs:
	$(warning The '$(PDFLATEX)' command was not found. Make sure you have it installed and in PATH to produce PDF output.)
	@echo "  SKIP    Sphinx $@ target."

else # HAVE_PDFLATEX

pdfdocs: latexdocs
	@$(srctree)/scripts/sphinx-pre-install --version-check
	$(foreach var,$(SPHINXDIRS), $(MAKE) PDFLATEX="$(PDFLATEX)" LATEXOPTS="$(LATEXOPTS)" -C $(BUILDDIR)/$(var)/latex || exit;)

endif # HAVE_PDFLATEX

epubdocs:
	@$(srctree)/scripts/sphinx-pre-install --version-check
	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,epub,$(var),epub,$(var)))

xmldocs:
	@$(srctree)/scripts/sphinx-pre-install --version-check
	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,xml,$(var),xml,$(var)))

endif # HAVE_SPHINX

# The following targets are independent of HAVE_SPHINX, and the rules should
# work or silently pass without Sphinx.

refcheckdocs:
	$(Q)cd $(srctree);scripts/documentation-file-ref-check

cleandocs:
	$(Q)rm -rf $(BUILDDIR)
	$(Q)$(MAKE) BUILDDIR=$(abspath $(BUILDDIR)) $(build)=Documentation/media clean

dochelp:
	@echo  ' Linux kernel internal documentation in different formats from ReST:'
	@echo  '  htmldocs        - HTML'
	@echo  '  latexdocs       - LaTeX'
	@echo  '  pdfdocs         - PDF'
	@echo  '  epubdocs        - EPUB'
	@echo  '  xmldocs         - XML'
	@echo  '  linkcheckdocs   - check for broken external links'
	@echo  '                    (will connect to external hosts)'
	@echo  '  refcheckdocs    - check for references to non-existing files under'
	@echo  '                    Documentation'
	@echo  '  cleandocs       - clean all generated files'
	@echo
	@echo  '  make SPHINXDIRS="s1 s2" [target] Generate only docs of folder s1, s2'
	@echo  '  valid values for SPHINXDIRS are: $(_SPHINXDIRS)'
	@echo
	@echo  '  make SPHINX_CONF={conf-file} [target] use *additional* sphinx-build'
	@echo  '  configuration. This is e.g. useful to build with nit-picking config.'
	@echo
	@echo  '  Default location for the generated documents is Documentation/output'
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