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Piotr Jaroszynski 61c6de6672 fs/iomap.c: get/put the page in iomap_page_create/release()
migrate_page_move_mapping() expects pages with private data set to have
a page_count elevated by 1.  This is what used to happen for xfs through
the buffer_heads code before the switch to iomap in commit 82cb14175e
("xfs: add support for sub-pagesize writeback without buffer_heads").
Not having the count elevated causes move_pages() to fail on memory
mapped files coming from xfs.

Make iomap compatible with the migrate_page_move_mapping() assumption by
elevating the page count as part of iomap_page_create() and lowering it
in iomap_page_release().

It causes the move_pages() syscall to misbehave on memory mapped files
from xfs.  It does not not move any pages, which I suppose is "just" a
perf issue, but it also ends up returning a positive number which is out
of spec for the syscall.  Talking to Michal Hocko, it sounds like
returning positive numbers might be a necessary update to move_pages()
anyway though
(https://lkml.kernel.org/r/20181116114955.GJ14706@dhcp22.suse.cz).

I only hit this in tests that verify that move_pages() actually moved
the pages.  The test also got confused by the positive return from
move_pages() (it got treated as a success as positive numbers were not
expected and not handled) making it a bit harder to track down what's
going on.

Link: http://lkml.kernel.org/r/20181115184140.1388751-1-pjaroszynski@nvidia.com
Fixes: 82cb14175e ("xfs: add support for sub-pagesize writeback without buffer_heads")
Signed-off-by: Piotr Jaroszynski <pjaroszynski@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Brian Foster <bfoster@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-14 15:05:45 -08:00
arch arch/sh/include/asm/io.h: provide prototypes for PCI I/O mapping in asm/io.h 2018-12-14 15:05:45 -08:00
block blk-mq: punt failed direct issue to dispatch list 2018-12-07 08:16:11 -07:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: user - Disable statistics interface 2018-12-07 13:56:08 +08:00
Documentation XArray updates for 4.20-rc7 2018-12-13 16:35:58 -08:00
drivers Pin control fixes for the v4.20 series: 2018-12-14 09:17:17 -08:00
firmware
fs fs/iomap.c: get/put the page in iomap_page_create/release() 2018-12-14 15:05:45 -08:00
include mm/sparse: add common helper to mark all memblocks present 2018-12-14 15:05:45 -08:00
init psi: fix reference to kernel commandline enable 2018-12-14 15:05:45 -08:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel While running various ftrace tests on new development code, the kmemleak 2018-12-12 18:15:29 -08:00
lib XArray: Fix xa_alloc when id exceeds max 2018-12-13 14:07:33 -05:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
mm hugetlbfs: call VM_BUG_ON_PAGE earlier in free_huge_page() 2018-12-14 15:05:45 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-12-09 15:12:33 -08:00
samples VFIO updates for v4.20 2018-10-31 11:01:38 -07:00
scripts Fixes for stackleak 2018-12-07 13:13:07 -08:00
security selinux/stable-4.20 PR 20181129 2018-11-29 10:15:06 -08:00
sound ALSA: hda/realtek: Enable audio jacks of ASUS UX433FN/UX333FA with ALC294 2018-12-10 11:25:22 +01:00
tools XArray updates for 4.20-rc7 2018-12-13 16:35:58 -08:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt Revert "mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks" 2018-10-26 16:25:19 -07:00
.clang-format page cache: Convert find_get_pages_contig to XArray 2018-10-21 10:46:34 -04:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap mailmap: Update email for Punit Agrawal 2018-11-05 10:02:11 +00:00
COPYING
CREDITS MAINTAINERS: update entry for MMP platform 2018-12-03 12:39:57 -08:00
Kbuild
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS drm vmwgfx, mediatek, nouveau, amdgpu, rockchip, intel fixes 2018-12-14 09:12:02 -08:00
Makefile Linux 4.20-rc6 2018-12-09 15:31:00 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.