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Ira Weiny 49dac5e017 mm/highmem: Lift memcpy_[to|from]_page to core
[ Upstream commit bb90d4bc7b6a536b2e4db45f4763e467c2008251 ]

Working through a conversion to a call kmap_local_page() instead of
kmap() revealed many places where the pattern kmap/memcpy/kunmap
occurred.

Eric Biggers, Matthew Wilcox, Christoph Hellwig, Dan Williams, and Al
Viro all suggested putting this code into helper functions.  Al Viro
further pointed out that these functions already existed in the iov_iter
code.[1]

Various locations for the lifted functions were considered.

Headers like mm.h or string.h seem ok but don't really portray the
functionality well.  pagemap.h made some sense but is for page cache
functionality.[2]

Another alternative would be to create a new header for the promoted
memcpy functions, but it masks the fact that these are designed to copy
to/from pages using the kernel direct mappings and complicates matters
with a new header.

Placing these functions in 'highmem.h' is suboptimal especially with the
changes being proposed in the functionality of kmap.  From a caller
perspective including/using 'highmem.h' implies that the functions
defined in that header are only required when highmem is in use which is
increasingly not the case with modern processors.  However, highmem.h is
where all the current functions like this reside (zero_user(),
clear_highpage(), clear_user_highpage(), copy_user_highpage(), and
copy_highpage()).  So it makes the most sense even though it is
distasteful for some.[3]

Lift memcpy_to_page() and memcpy_from_page() to pagemap.h.

[1] https://lore.kernel.org/lkml/20201013200149.GI3576660@ZenIV.linux.org.uk/
    https://lore.kernel.org/lkml/20201013112544.GA5249@infradead.org/

[2] https://lore.kernel.org/lkml/20201208122316.GH7338@casper.infradead.org/

[3] https://lore.kernel.org/lkml/20201013200149.GI3576660@ZenIV.linux.org.uk/#t
    https://lore.kernel.org/lkml/20201208163814.GN1563847@iweiny-DESK2.sc.intel.com/

Cc: Boris Pismenny <borisp@mellanox.com>
Cc: Or Gerlitz <gerlitz.or@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Suggested-by: Dan Williams <dan.j.williams@intel.com>
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Suggested-by: Eric Biggers <ebiggers@kernel.org>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Stable-dep-of: 956510c0c743 ("fs: ext4: initialize fsdata in pagecache_write()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-01-18 11:41:55 +01:00
arch KVM: nVMX: Properly expose ENABLE_USR_WAIT_PAUSE control to L1 2023-01-18 11:41:54 +01:00
block blk-mq: fix possible memleak when register 'hctx' failed 2023-01-18 11:41:38 +01:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:11:22 +02:00
crypto crypto: tcrypt - Fix multibuffer skcipher speed test mem leak 2023-01-18 11:41:19 +01:00
Documentation ASoC: dt-bindings: wcd9335: fix reset line polarity in example 2023-01-18 11:41:06 +01:00
drivers ravb: Fix "failed to switch device to config mode" message during unbind 2023-01-18 11:41:54 +01:00
fs ext4: correct inconsistent error msg in nojournal mode 2023-01-18 11:41:55 +01:00
include mm/highmem: Lift memcpy_[to|from]_page to core 2023-01-18 11:41:55 +01:00
init init/Kconfig: fix CC_HAS_ASM_GOTO_TIED_OUTPUT test with dash 2022-12-08 11:22:59 +01:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:23:06 +01:00
kernel tracing: Fix infinite loop in tracing_read_pipe on overflowed print_trace_line 2023-01-18 11:41:48 +01:00
lib mm/highmem: Lift memcpy_[to|from]_page to core 2023-01-18 11:41:55 +01:00
LICENSES
mm mm, compaction: fix fast_isolate_around() to stay within boundaries 2023-01-18 11:41:44 +01:00
net net/af_packet: make sure to pull mac header 2023-01-18 11:41:45 +01:00
samples samples: vfio-mdev: Fix missing pci_disable_device() in mdpy_fb_probe() 2023-01-18 11:41:26 +01:00
scripts scripts/faddr2line: Fix regression in name resolution on ppc64le 2022-12-08 11:23:02 +01:00
security device_cgroup: Roll back to original exceptions after copy failure 2023-01-18 11:41:50 +01:00
sound ALSA: line6: fix stack overflow in line6_midi_transmit 2023-01-18 11:41:44 +01:00
tools KVM: VMX: Fix the spelling of CPU_BASED_USE_TSC_OFFSETTING 2023-01-18 11:41:54 +01:00
usr
virt KVM: arm64: vgic: Fix exit condition in scan_its_table() 2022-10-29 10:20:35 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS MAINTAINERS: add Chandan as xfs maintainer for 5.4.y 2022-09-28 11:03:58 +02:00
Makefile Linux 5.4.228 2022-12-19 12:24:17 +01:00
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.