cb38f82043
cpa_4k_install could be accessed concurrently as noticed by KCSAN, read to 0xffffffffaa59a000 of 8 bytes by interrupt on cpu 7: cpa_inc_4k_install arch/x86/mm/pat/set_memory.c:131 [inline] __change_page_attr+0x10cf/0x1840 arch/x86/mm/pat/set_memory.c:1514 __change_page_attr_set_clr+0xce/0x490 arch/x86/mm/pat/set_memory.c:1636 __set_pages_np+0xc4/0xf0 arch/x86/mm/pat/set_memory.c:2148 __kernel_map_pages+0xb0/0xc8 arch/x86/mm/pat/set_memory.c:2178 kernel_map_pages include/linux/mm.h:2719 [inline] <snip> write to 0xffffffffaa59a000 of 8 bytes by task 1 on cpu 6: cpa_inc_4k_install arch/x86/mm/pat/set_memory.c:131 [inline] __change_page_attr+0x10ea/0x1840 arch/x86/mm/pat/set_memory.c:1514 __change_page_attr_set_clr+0xce/0x490 arch/x86/mm/pat/set_memory.c:1636 __set_pages_p+0xc4/0xf0 arch/x86/mm/pat/set_memory.c:2129 __kernel_map_pages+0x2e/0xc8 arch/x86/mm/pat/set_memory.c:2176 kernel_map_pages include/linux/mm.h:2719 [inline] <snip> Both accesses are due to the same "cpa_4k_install++" in cpa_inc_4k_install. A data race here could be potentially undesirable: depending on compiler optimizations or how x86 executes a non-LOCK'd increment, it may lose increments, corrupt the counter, etc. Since this counter only seems to be used for printing some stats, this data race itself is unlikely to cause harm to the system though. Thus, mark this intentional data race using the data_race() marco. Suggested-by: Macro Elver <elver@google.com> Signed-off-by: Qian Cai <cai@lca.pw> Acked-by: Borislav Petkov <bp@suse.de> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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.
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.