iov_iter: Fix iov_iter_extract_pages() with zero-sized entries

iov_iter_extract_pages() doesn't correctly handle skipping over initial
zero-length entries in ITER_KVEC and ITER_BVEC-type iterators.

iov_iter: Fix iov_iter_extract_pages() with zero-sized entries

iov_iter_extract_pages() doesn't correctly handle skipping over initial
zero-length entries in ITER_KVEC and ITER_BVEC-type iterators.

The problem is that it accidentally reduces maxsize to 0 when it
skipping and thus runs to the end of the array and returns 0.

Fix this by sticking the calculated size-to-copy in a new variable
rather than back in maxsize.

Fixes: 7d58fe731028 ("iov_iter: Add a function to extract a page list from an iterator")
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: David Hildenbrand <david@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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iov_iter: Export import_ubuf()

Export import_ubuf() to be used in sound subsystem for generic memory
handling as Linus suggested. It's used for constructing an iov_iter
of a single segment user-spa

iov_iter: Export import_ubuf()

Export import_ubuf() to be used in sound subsystem for generic memory
handling as Linus suggested. It's used for constructing an iov_iter
of a single segment user-space copy for PCM data.

Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/CAHk-=wh-mUL6mp4chAc6E_UjwpPLyCPRCJK+iB4ZMD2BqjwGHA@mail.gmail.com
Link: https://lore.kernel.org/r/20230815190136.8987-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

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iov_iter: Add copy_folio_from_iter_atomic()

Add a folio wrapper around copy_page_from_iter_atomic().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwon

iov_iter: Add copy_folio_from_iter_atomic()

Add a folio wrapper around copy_page_from_iter_atomic().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

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iov_iter: Handle compound highmem pages in copy_page_from_iter_atomic()

copy_page_from_iter_atomic() already handles !highmem compound
pages correctly, but if we are passed a highmem compound page,

iov_iter: Handle compound highmem pages in copy_page_from_iter_atomic()

copy_page_from_iter_atomic() already handles !highmem compound
pages correctly, but if we are passed a highmem compound page,
each base page needs to be mapped & unmapped individually.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kent Overstreet <kent.overstreet@linux.dev>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Tested-by: Kent Overstreet <kent.overstreet@linux.dev>

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iov_iter: Map the page later in copy_page_from_iter_atomic()

Remove a couple of calls to kunmap_atomic() in the rare error cases.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Review

iov_iter: Map the page later in copy_page_from_iter_atomic()

Remove a couple of calls to kunmap_atomic() in the rare error cases.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kent Overstreet <kent.overstreet@linux.dev>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

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iov_iter: Mark copy_iovec_from_user() noclone

Extend commit 50f9a76ef127 ("iov_iter: Mark
copy_compat_iovec_from_user() noinline") to also cover
copy_iovec_from_user(). Different compiler versions c

iov_iter: Mark copy_iovec_from_user() noclone

Extend commit 50f9a76ef127 ("iov_iter: Mark
copy_compat_iovec_from_user() noinline") to also cover
copy_iovec_from_user(). Different compiler versions cause the same
problem on different functions.

lib/iov_iter.o: warning: objtool: .altinstr_replacement+0x1f: redundant UACCESS disable
lib/iov_iter.o: warning: objtool: iovec_from_user+0x84: call to copy_iovec_from_user.part.0() with UACCESS enabled
lib/iov_iter.o: warning: objtool: __import_iovec+0x143: call to copy_iovec_from_user.part.0() with UACCESS enabled

Fixes: 50f9a76ef127 ("iov_iter: Mark copy_compat_iovec_from_user() noinline")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lkml.kernel.org/r/20230616124354.GD4253@hirez.programming.kicks-ass.net

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iov_iter: remove iov_iter_get_pages and iov_iter_get_pages_alloc

Now that the direct I/O helpers have switched to use
iov_iter_extract_pages, these helpers are unused.

Signed-off-by: Christoph Hell

iov_iter: remove iov_iter_get_pages and iov_iter_get_pages_alloc

Now that the direct I/O helpers have switched to use
iov_iter_extract_pages, these helpers are unused.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20230614140341.521331-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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iov_iter: Kill ITER_PIPE

The ITER_PIPE-type iterator was only used by generic_file_splice_read() and
that has been replaced and removed. This leaves ITER_PIPE unused - so
remove it too.

Signed-off

iov_iter: Kill ITER_PIPE

The ITER_PIPE-type iterator was only used by generic_file_splice_read() and
that has been replaced and removed. This leaves ITER_PIPE unused - so
remove it too.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
cc: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: David Hildenbrand <david@redhat.com>
cc: John Hubbard <jhubbard@nvidia.com>
cc: linux-mm@kvack.org
cc: linux-block@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20230522135018.2742245-31-dhowells@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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mm: hwpoison: coredump: support recovery from dump_user_range()

dump_user_range() is used to copy the user page to a coredump file, but if
a hardware memory error occurred during copy, which called

mm: hwpoison: coredump: support recovery from dump_user_range()

dump_user_range() is used to copy the user page to a coredump file, but if
a hardware memory error occurred during copy, which called from
__kernel_write_iter() in dump_user_range(), it crashes,

CPU: 112 PID: 7014 Comm: mca-recover Not tainted 6.3.0-rc2 #425

pc : __memcpy+0x110/0x260
lr : _copy_from_iter+0x3bc/0x4c8
...
Call trace:
__memcpy+0x110/0x260
copy_page_from_iter+0xcc/0x130
pipe_write+0x164/0x6d8
__kernel_write_iter+0x9c/0x210
dump_user_range+0xc8/0x1d8
elf_core_dump+0x308/0x368
do_coredump+0x2e8/0xa40
get_signal+0x59c/0x788
do_signal+0x118/0x1f8
do_notify_resume+0xf0/0x280
el0_da+0x130/0x138
el0t_64_sync_handler+0x68/0xc0
el0t_64_sync+0x188/0x190

Generally, the '->write_iter' of file ops will use copy_page_from_iter()
and copy_page_from_iter_atomic(), change memcpy() to copy_mc_to_kernel()
in both of them to handle #MC during source read, which stop coredump
processing and kill the task instead of kernel panic, but the source
address may not always a user address, so introduce a new copy_mc flag in
struct iov_iter{} to indicate that the iter could do a safe memory copy,
also introduce the helpers to set/cleck the flag, for now, it's only used
in coredump's dump_user_range(), but it could expand to any other
scenarios to fix the similar issue.

Link: https://lkml.kernel.org/r/20230417045323.11054-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Tong Tiangen <tongtiangen@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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iov: improve copy_iovec_from_user() code generation

Use the same pattern as the compat version of this code does: instead of
copying the whole array to a kernel buffer and then having a separate
pha

iov: improve copy_iovec_from_user() code generation

Use the same pattern as the compat version of this code does: instead of
copying the whole array to a kernel buffer and then having a separate
phase of verifying it, just do it one entry at a time, verifying as you
go.

On Jens' /dev/zero readv() test this improves performance by ~6%.

[ This was obviously triggered by Jens' ITER_UBUF updates series ]

Reported-and-tested-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/all/de35d11d-bce7-e976-7372-1f2caf417103@kernel.dk/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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iov_iter: Mark copy_compat_iovec_from_user() noinline

After commit 6376ce56feb6 ("iov_iter: import single vector iovecs as
ITER_UBUF"), GCC does an inter-procedural compiler optimization which
moves

iov_iter: Mark copy_compat_iovec_from_user() noinline

After commit 6376ce56feb6 ("iov_iter: import single vector iovecs as
ITER_UBUF"), GCC does an inter-procedural compiler optimization which
moves the user_access_begin() out of copy_compat_iovec_from_user() and
into its callers:

lib/iov_iter.o: warning: objtool: .altinstr_replacement+0x0: redundant UACCESS disable
lib/iov_iter.o: warning: objtool: iovec_from_user.part.0+0xc7: call to copy_compat_iovec_from_user.part.0() with UACCESS enabled
lib/iov_iter.o: warning: objtool: __import_iovec+0x21d: call to copy_compat_iovec_from_user.part.0() with UACCESS enabled

Enforce the "no UACCESS enable across function boundaries" rule by
disabling cloning for copy_compat_iovec_from_user().

Fixes: 6376ce56feb6 ("iov_iter: import single vector iovecs as ITER_UBUF")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
https://lkml.kernel.org/lkml/20230327120017.6bb826d7@canb.auug.org.au
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Tested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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iov_iter: add copy_page_to_iter_nofault()

Provide a means to copy a page to user space from an iterator, aborting if
a page fault would occur. This supports compound pages, but may be passed
a tail

iov_iter: add copy_page_to_iter_nofault()

Provide a means to copy a page to user space from an iterator, aborting if
a page fault would occur. This supports compound pages, but may be passed
a tail page with an offset extending further into the compound page, so we
cannot pass a folio.

This allows for this function to be called from atomic context and _try_
to user pages if they are faulted in, aborting if not.

The function does not use _copy_to_iter() in order to not specify
might_fault(), this is similar to copy_page_from_iter_atomic().

This is being added in order that an iteratable form of vread() can be
implemented while holding spinlocks.

Link: https://lkml.kernel.org/r/19734729defb0f498a76bdec1bef3ac48a3af3e8.1679511146.git.lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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iov_iter: import single vector iovecs as ITER_UBUF

Add a special case to __import_iovec(), which imports a single segment
iovec as an ITER_UBUF rather than an ITER_IOVEC. ITER_UBUF is cheaper
to ite

iov_iter: import single vector iovecs as ITER_UBUF

Add a special case to __import_iovec(), which imports a single segment
iovec as an ITER_UBUF rather than an ITER_IOVEC. ITER_UBUF is cheaper
to iterate than ITER_IOVEC, and for a single segment iovec, there's no
point in using a segmented iterator.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

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iov_iter: convert import_single_range() to ITER_UBUF

Since we're just importing a single vector, we don't have to turn it
into an ITER_IOVEC. Instead turn it into an ITER_UBUF, which is cheaper
to i

iov_iter: convert import_single_range() to ITER_UBUF

Since we're just importing a single vector, we don't have to turn it
into an ITER_IOVEC. Instead turn it into an ITER_UBUF, which is cheaper
to iterate.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

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iov_iter: add iter_iovec() helper

This returns a pointer to the current iovec entry in the iterator. Only
useful with ITER_IOVEC right now, but it prepares us to treat ITER_UBUF
and ITER_IOVEC ident

iov_iter: add iter_iovec() helper

This returns a pointer to the current iovec entry in the iterator. Only
useful with ITER_IOVEC right now, but it prepares us to treat ITER_UBUF
and ITER_IOVEC identically for the first segment.

Rename struct iov_iter->iov to iov_iter->__iov to find any potentially
troublesome spots, and also to prevent anyone from adding new code that
accesses iter->iov directly.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

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iov_iter: Add a function to extract a page list from an iterator

Add a function, iov_iter_extract_pages(), to extract a list of pages from
an iterator. The pages may be returned with a pin added or

iov_iter: Add a function to extract a page list from an iterator

Add a function, iov_iter_extract_pages(), to extract a list of pages from
an iterator. The pages may be returned with a pin added or nothing,
depending on the type of iterator.

Add a second function, iov_iter_extract_will_pin(), to determine how the
cleanup should be done.

There are two cases:

(1) ITER_IOVEC or ITER_UBUF iterator.

Extracted pages will have pins (FOLL_PIN) obtained on them so that a
concurrent fork() will forcibly copy the page so that DMA is done
to/from the parent's buffer and is unavailable to/unaffected by the
child process.

iov_iter_extract_will_pin() will return true for this case. The
caller should use something like unpin_user_page() to dispose of the
page.

(2) Any other sort of iterator.

No refs or pins are obtained on the page, the assumption is made that
the caller will manage page retention.

iov_iter_extract_will_pin() will return false. The pages don't need
additional disposal.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: John Hubbard <jhubbard@nvidia.com>
cc: David Hildenbrand <david@redhat.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
Signed-off-by: Steve French <stfrench@microsoft.com>

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iov_iter: Define flags to qualify page extraction.

Define flags to qualify page extraction to pass into iov_iter_*_pages*()
rather than passing in FOLL_* flags.

For now only a flag to allow peer-to

iov_iter: Define flags to qualify page extraction.

Define flags to qualify page extraction to pass into iov_iter_*_pages*()
rather than passing in FOLL_* flags.

For now only a flag to allow peer-to-peer DMA is supported.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Logan Gunthorpe <logang@deltatee.com>
cc: linux-fsdevel@vger.kernel.org
cc: linux-block@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>

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splice: Add a func to do a splice from a buffered file without ITER_PIPE

Provide a function to do splice read from a buffered file, pulling the
folios out of the pagecache directly by calling filema

splice: Add a func to do a splice from a buffered file without ITER_PIPE

Provide a function to do splice read from a buffered file, pulling the
folios out of the pagecache directly by calling filemap_get_pages() to do
any required reading and then pasting the returned folios into the pipe.

A helper function is provided to do the actual folio pasting and will
handle multipage folios by splicing as many of the relevant subpages as
will fit into the pipe.

The code is loosely based on filemap_read() and might belong in
mm/filemap.c with that as it needs to use filemap_get_pages().

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
cc: Christoph Hellwig <hch@lst.de>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: David Hildenbrand <david@redhat.com>
cc: John Hubbard <jhubbard@nvidia.com>
cc: linux-mm@kvack.org
cc: linux-block@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>

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iov_iter: move iter_ubuf check inside restore WARN

io_uring is using iter_ubuf types for single vector requests. We expect
state restore may happen for this type now, and it is already handled
corre

iov_iter: move iter_ubuf check inside restore WARN

io_uring is using iter_ubuf types for single vector requests. We expect
state restore may happen for this type now, and it is already handled
correctly, so suppress the warning.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Christoph Hellwig <hch@lst.de>

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iov: add import_ubuf()

Like import_single_range(), but for ITER_UBUF.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@

iov: add import_ubuf()

Like import_single_range(), but for ITER_UBUF.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

show more ...

iov_iter: saner checks for attempt to copy to/from iterator

instead of "don't do it to ITER_PIPE" check for ->data_source being
false on copying from iterator. Check for !->data_source for
copying

iov_iter: saner checks for attempt to copy to/from iterator

instead of "don't do it to ITER_PIPE" check for ->data_source being
false on copying from iterator. Check for !->data_source for
copying to iterator, while we are at it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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csum_and_copy_to_iter(): handle ITER_DISCARD

Not hard to implement - we are not copying anything here, so
csum_and_memcpy() is not usable, but calculating a checksum
of source directly is trivial...

csum_and_copy_to_iter(): handle ITER_DISCARD

Not hard to implement - we are not copying anything here, so
csum_and_memcpy() is not usable, but calculating a checksum
of source directly is trivial...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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get rid of unlikely() on page_copy_sane() calls

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

iov_iter: introduce iov_iter_get_pages_[alloc_]flags()

Add iov_iter_get_pages_flags() and iov_iter_get_pages_alloc_flags()
which take a flags argument that is passed to get_user_pages_fast().

This

iov_iter: introduce iov_iter_get_pages_[alloc_]flags()

Add iov_iter_get_pages_flags() and iov_iter_get_pages_alloc_flags()
which take a flags argument that is passed to get_user_pages_fast().

This is so that FOLL_PCI_P2PDMA can be passed when appropriate.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221021174116.7200-4-logang@deltatee.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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instrumented.h: allow instrumenting both sides of copy_from_user()

Introduce instrument_copy_from_user_before() and
instrument_copy_from_user_after() hooks to be invoked before and after the
call to

instrumented.h: allow instrumenting both sides of copy_from_user()

Introduce instrument_copy_from_user_before() and
instrument_copy_from_user_after() hooks to be invoked before and after the
call to copy_from_user().

KASAN and KCSAN will be only using instrument_copy_from_user_before(), but
for KMSAN we'll need to insert code after copy_from_user().

Link: https://lkml.kernel.org/r/20220915150417.722975-4-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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