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Revision c403f6a3a792a6601185497c12b0bdf4be880439 authored by Qian Cai on 15 August 2020, 00:31:53 UTC, committed by Linus Torvalds on 15 August 2020, 02:56:57 UTC 
mm: annotate a data race in page_zonenum()
 
 BUG: KCSAN: data-race in page_cpupid_xchg_last / put_page

 write (marked) to 0xfffffc0d48ec1a00 of 8 bytes by task 91442 on cpu 3:
  page_cpupid_xchg_last+0x51/0x80
  page_cpupid_xchg_last at mm/mmzone.c:109 (discriminator 11)
  wp_page_reuse+0x3e/0xc0
  wp_page_reuse at mm/memory.c:2453
  do_wp_page+0x472/0x7b0
  do_wp_page at mm/memory.c:2798
  __handle_mm_fault+0xcb0/0xd00
  handle_pte_fault at mm/memory.c:4049
  (inlined by) __handle_mm_fault at mm/memory.c:4163
  handle_mm_fault+0xfc/0x2f0
  handle_mm_fault at mm/memory.c:4200
  do_page_fault+0x263/0x6f9
  do_user_addr_fault at arch/x86/mm/fault.c:1465
  (inlined by) do_page_fault at arch/x86/mm/fault.c:1539
  page_fault+0x34/0x40

 read to 0xfffffc0d48ec1a00 of 8 bytes by task 94817 on cpu 69:
  put_page+0x15a/0x1f0
  page_zonenum at include/linux/mm.h:923
  (inlined by) is_zone_device_page at include/linux/mm.h:929
  (inlined by) page_is_devmap_managed at include/linux/mm.h:948
  (inlined by) put_page at include/linux/mm.h:1023
  wp_page_copy+0x571/0x930
  wp_page_copy at mm/memory.c:2615
  do_wp_page+0x107/0x7b0
  __handle_mm_fault+0xcb0/0xd00
  handle_mm_fault+0xfc/0x2f0
  do_page_fault+0x263/0x6f9
  page_fault+0x34/0x40

 Reported by Kernel Concurrency Sanitizer on:
 CPU: 69 PID: 94817 Comm: systemd-udevd Tainted: G        W  O L 5.5.0-next-20200204+ #6
 Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019

A page never changes its zone number. The zone number happens to be
stored in the same word as other bits which are modified, but the zone
number bits will never be modified by any other write, so it can accept
a reload of the zone bits after an intervening write and it don't need
to use READ_ONCE(). Thus, annotate this data race using
ASSERT_EXCLUSIVE_BITS() to also assert that there are no concurrent
writes to it.

Suggested-by: Marco Elver <elver@google.com>
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Link: http://lkml.kernel.org/r/1581619089-14472-1-git-send-email-cai@lca.pw
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 7e0cc01
Raw File
Makefile 
# SPDX-License-Identifier: GPL-2.0
#
# kbuild file for usr/ - including initramfs image
#

# cmd_bzip2, cmd_lzma, cmd_lzo, cmd_lz4 from scripts/Makefile.lib appends the
# size at the end of the compressed file, which unfortunately does not work
# with unpack_to_rootfs(). Make size_append no-op.
override size_append := :

compress-y					:= shipped
compress-$(CONFIG_INITRAMFS_COMPRESSION_GZIP)	:= gzip
compress-$(CONFIG_INITRAMFS_COMPRESSION_BZIP2)	:= bzip2
compress-$(CONFIG_INITRAMFS_COMPRESSION_LZMA)	:= lzma
compress-$(CONFIG_INITRAMFS_COMPRESSION_XZ)	:= xzmisc
compress-$(CONFIG_INITRAMFS_COMPRESSION_LZO)	:= lzo
compress-$(CONFIG_INITRAMFS_COMPRESSION_LZ4)	:= lz4
compress-$(CONFIG_INITRAMFS_COMPRESSION_ZSTD)	:= zstd

obj-$(CONFIG_BLK_DEV_INITRD) := initramfs_data.o

$(obj)/initramfs_data.o: $(obj)/initramfs_inc_data

ramfs-input := $(strip $(shell echo $(CONFIG_INITRAMFS_SOURCE)))
cpio-data :=

# If CONFIG_INITRAMFS_SOURCE is empty, generate a small initramfs with the
# default contents.
ifeq ($(ramfs-input),)
ramfs-input := $(srctree)/$(src)/default_cpio_list
endif

ifeq ($(words $(ramfs-input)),1)

# If CONFIG_INITRAMFS_SOURCE specifies a single file, and it is suffixed with
# .cpio, use it directly as an initramfs.
ifneq ($(filter %.cpio,$(ramfs-input)),)
cpio-data := $(ramfs-input)
endif

# If CONFIG_INITRAMFS_SOURCE specifies a single file, and it is suffixed with
# .cpio.*, use it directly as an initramfs, and avoid double compression.
ifeq ($(words $(subst .cpio.,$(space),$(ramfs-input))),2)
cpio-data := $(ramfs-input)
compress-y := shipped
endif

endif

# For other cases, generate the initramfs cpio archive based on the contents
# specified by CONFIG_INITRAMFS_SOURCE.
ifeq ($(cpio-data),)

cpio-data := $(obj)/initramfs_data.cpio

hostprogs := gen_init_cpio

# .initramfs_data.cpio.d is used to identify all files included
# in initramfs and to detect if any files are added/removed.
# Removed files are identified by directory timestamp being updated
# The dependency list is generated by gen_initramfs.sh -l
-include $(obj)/.initramfs_data.cpio.d

# do not try to update files included in initramfs
$(deps_initramfs): ;

quiet_cmd_initfs = GEN     $@
      cmd_initfs = \
	$(CONFIG_SHELL) $< -o $@ -l $(obj)/.initramfs_data.cpio.d \
	$(if $(CONFIG_INITRAMFS_ROOT_UID), -u $(CONFIG_INITRAMFS_ROOT_UID)) \
	$(if $(CONFIG_INITRAMFS_ROOT_GID), -g $(CONFIG_INITRAMFS_ROOT_GID)) \
	$(ramfs-input)

# We rebuild initramfs_data.cpio if:
# 1) Any included file is newer than initramfs_data.cpio
# 2) There are changes in which files are included (added or deleted)
# 3) If gen_init_cpio are newer than initramfs_data.cpio
# 4) Arguments to gen_initramfs.sh changes
$(obj)/initramfs_data.cpio: $(src)/gen_initramfs.sh $(obj)/gen_init_cpio $(deps_initramfs) FORCE
	$(call if_changed,initfs)

endif

$(obj)/initramfs_inc_data: $(cpio-data) FORCE
	$(call if_changed,$(compress-y))

targets += initramfs_data.cpio initramfs_inc_data

subdir-$(CONFIG_UAPI_HEADER_TEST) += include
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