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Linux kernel for uConsole
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Vivek Goyal 2afa6c13e4 dax: dax_layout_busy_page() should not unmap cow pages 
commit d75996dd02 upstream.

Vivek:

    "As of now dax_layout_busy_page() calls unmap_mapping_range() with last
     argument as 1, which says even unmap cow pages. I am wondering who needs
     to get rid of cow pages as well.

     I noticed one interesting side affect of this. I mount xfs with -o dax and
     mmaped a file with MAP_PRIVATE and wrote some data to a page which created
     cow page. Then I called fallocate() on that file to zero a page of file.
     fallocate() called dax_layout_busy_page() which unmapped cow pages as well
     and then I tried to read back the data I wrote and what I get is old
     data from persistent memory. I lost the data I had written. This
     read basically resulted in new fault and read back the data from
     persistent memory.

     This sounds wrong. Are there any users which need to unmap cow pages
     as well? If not, I am proposing changing it to not unmap cow pages.

     I noticed this while while writing virtio_fs code where when I tried
     to reclaim a memory range and that corrupted the executable and I
     was running from virtio-fs and program got segment violation."

Dan:

    "In fact the unmap_mapping_range() in this path is only to synchronize
     against get_user_pages_fast() and force it to call back into the
     filesystem to re-establish the mapping. COW pages should be left
     untouched by dax_layout_busy_page()."

Cc: <stable@vger.kernel.org>
Fixes: 5fac7408d8 ("mm, fs, dax: handle layout changes to pinned dax mappings")
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Link: https://lore.kernel.org/r/20190802192956.GA3032@redhat.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-08-16 10:12:52 +02:00
arch x86/purgatory: Do not use __builtin_memcpy and __builtin_memset 2019-08-16 10:12:50 +02:00
block block, scsi: Change the preempt-only flag into a counter 2019-08-04 09:30:57 +02:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: chacha20poly1305 - fix atomic sleep when using async algorithm 2019-07-26 09:14:19 +02:00
Documentation Documentation: Add swapgs description to the Spectre v1 documentation 2019-08-06 19:06:58 +02:00
drivers drm/i915: Fix wrong escape clock divisor init for GLK 2019-08-16 10:12:51 +02:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs dax: dax_layout_busy_page() should not unmap cow pages 2019-08-16 10:12:52 +02:00
include ALSA: compress: Fix regression on compressed capture streams 2019-08-16 10:12:47 +02:00
init initramfs: free initrd memory if opening /initrd.image fails 2019-06-15 11:54:01 +02:00
ipc ipc/mqueue.c: only perform resource calculation if user valid 2019-08-06 19:06:52 +02:00
kernel perf/core: Fix creating kernel counters for PMUs that override event->cpu 2019-08-16 10:12:50 +02:00
lib test_firmware: fix a memory leak bug 2019-08-16 10:12:49 +02:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy() 2019-08-16 10:12:40 +02:00
net mac80211: don't WARN on short WMM parameters from AP 2019-08-16 10:12:52 +02:00
samples samples, bpf: suppress compiler warning 2019-07-14 08:11:04 +02:00
scripts scripts/sphinx-pre-install: fix script for RHEL/CentOS 2019-08-16 10:12:44 +02:00
security selinux: fix memory leak in policydb_init() 2019-08-06 19:06:54 +02:00
sound ALSA: hda - Workaround for crackled sound on AMD controller (1022:1457) 2019-08-16 10:12:52 +02:00
tools perf probe: Avoid calling freeing routine multiple times for same pointer 2019-08-16 10:12:48 +02:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: arm/arm64: vgic: Fix kvm_device leak in vgic_its_destroy 2019-07-14 08:11:10 +02:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS platform/x86: Add Intel AtomISP2 dummy / power-management driver 2019-04-20 09:16:02 +02:00
Makefile Linux 4.19.66 2019-08-09 17:52:35 +02:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.