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Mathieu Desnoyers 2807c54b38 dax: add empty static inline for CONFIG_DAX=n 
Patch series "Introduce cpu_dcache_is_aliasing() to fix DAX regression",
v6.

This commit introduced in v4.0 prevents building FS_DAX on 32-bit ARM,
even on ARMv7 which does not have virtually aliased data caches:

commit d92576f116 ("dax: does not work correctly with virtual aliasing caches")

Even though it used to work fine before.

The root of the issue here is the fact that DAX was never designed to
handle virtually aliasing data caches (VIVT and VIPT with aliasing data
cache). It touches the pages through their linear mapping, which is not
consistent with the userspace mappings with virtually aliasing data
caches.

This patch series introduces cpu_dcache_is_aliasing() with the new
Kconfig option ARCH_HAS_CPU_CACHE_ALIASING and implements it for all
architectures. The implementation of cpu_dcache_is_aliasing() is either
evaluated to a constant at compile-time or a runtime check, which is
what is needed on ARM.

With this we can basically narrow down the list of architectures which
are unsupported by DAX to those which are really affected.


This patch (of 9):

When building a kernel with CONFIG_DAX=n, all uses of set_dax_nocache()
and set_dax_nomc() need to be either within regions of code or compile
units which are explicitly not compiled, or they need to rely on compiler
optimizations to eliminate calls to those undefined symbols.

It appears that at least the openrisc and loongarch architectures don't
end up eliminating those undefined symbols even if they are provably
within code which is eliminated due to conditional branches depending on
constants.

Implement empty static inline functions for set_dax_nocache() and
set_dax_nomc() in CONFIG_DAX=n to ensure those undefined references are
removed.

Link: https://lkml.kernel.org/r/20240215144633.96437-1-mathieu.desnoyers@efficios.com
Link: https://lkml.kernel.org/r/20240215144633.96437-2-mathieu.desnoyers@efficios.com
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202402140037.wGfA1kqX-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202402131351.a0FZOgEG-lkp@intel.com/
Fixes: 7ac5360cd4 ("dax: remove the copy_from_iter and copy_to_iter methods")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Michael Sclafani <dm-devel@lists.linux.dev>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-02-22 15:27:19 -08:00
arch arm64/mm: automatically fold contpte mappings 2024-02-22 15:27:19 -08:00
block blk-iocost: Fix an UBSAN shift-out-of-bounds warning 2024-02-08 10:11:39 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto crypto: algif_hash - Remove bogus SGL free on zero-length error path 2024-02-02 18:08:12 +08:00
Documentation mm/cma: add sysfs file 'release_pages_success' 2024-02-22 10:24:57 -08:00
drivers nvdimm/pmem: fix leak on dax_add_host() failure 2024-02-22 15:27:19 -08:00
fs userfaultfd: fix return error if mmap_changing is non-zero in MOVE ioctl 2024-02-22 10:24:38 -08:00
include dax: add empty static inline for CONFIG_DAX=n 2024-02-22 15:27:19 -08:00
init arm64, powerpc, riscv, s390, x86: ptdump: refactor CONFIG_DEBUG_WX 2024-02-22 10:24:47 -08:00
io_uring io_uring/net: fix multishot accept overflow handling 2024-02-14 18:30:19 -07:00
ipc shm: Slim down dependencies 2023-12-20 19:26:31 -05:00
kernel mm/cma: drop CONFIG_CMA_DEBUG 2024-02-22 10:24:53 -08:00
lib XArray: add cmpxchg order test 2024-02-22 10:24:48 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: add pte_batch_hint() to reduce scanning in folio_pte_batch() 2024-02-22 15:27:18 -08:00
net Including fixes from can, wireless and netfilter. 2024-02-15 11:39:27 -08:00
rust Rust changes for v6.8 2024-01-11 13:05:41 -08:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-09 15:57:48 -08:00
scripts scripts/gdb/vmalloc: fix vmallocinfo error 2024-02-21 16:00:02 -08:00
security lsm/stable-6.8 PR 20240215 2024-02-16 07:58:43 -08:00
sound ALSA: usb-audio: More relaxed check of MIDI jack names 2024-02-15 16:56:05 +01:00
tools selftests: add zswapin and no zswap tests 2024-02-22 15:27:16 -08:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt Generic: 2024-01-17 13:03:37 -08:00
.clang-format clang-format: Update with v6.7-rc4's for_each macro list 2023-12-08 23:54:38 +01:00
.cocciconfig
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.mailmap MAINTAINERS: mailmap: update Shakeel's email address 2024-02-20 14:20:50 -08:00
.rustfmt.toml
COPYING
CREDITS MAINTAINERS: supplement of zswap maintainers update 2024-01-25 23:52:21 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
MAINTAINERS selftests: zswap: add zswap selftest file to zswap maintainer entry 2024-02-22 15:27:16 -08:00
Makefile Linux 6.8-rc5 2024-02-18 12:56:25 -08:00
README

README 

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.