linux-stable.git/include/linux/shmem_fs.h, branch v4.14.331

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02T10:10:55+00:00

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart 
Reviewed-by: Philippe Ombredanne 
Reviewed-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

userfaultfd: shmem: add shmem_mfill_zeropage_pte for userfaultfd support

2017-09-07T00:27:28+00:00

shmem_mfill_zeropage_pte is the low level routine that implements the
userfaultfd UFFDIO_ZEROPAGE command.  Since for shmem mappings zero
pages are always allocated and accounted, the new method is a slight
extension of the existing shmem_mcopy_atomic_pte.

Link: http://lkml.kernel.org/r/1497939652-16528-4-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport 
Cc: "Kirill A. Shutemov" 
Cc: Andrea Arcangeli 
Cc: Hillf Danton 
Cc: Hugh Dickins 
Cc: Pavel Emelyanov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: remove shmem_mapping() shmem_zero_setup() duplicates

2017-02-25T01:46:56+00:00

Remove the prototypes for shmem_mapping() and shmem_zero_setup() from
linux/mm.h, since they are already provided in linux/shmem_fs.h.  But
shmem_fs.h must then provide the inline stub for shmem_mapping() when
CONFIG_SHMEM is not set, and a few more cfiles now need to #include it.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1702081658250.1549@eggly.anvils
Signed-off-by: Hugh Dickins 
Cc: Johannes Weiner 
Cc: Michal Simek 
Cc: Michael Ellerman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support

2017-02-23T00:41:28+00:00

shmem_mcopy_atomic_pte is the low level routine that implements the
userfaultfd UFFDIO_COPY command.  It is based on the existing
mcopy_atomic_pte routine with modifications for shared memory pages.

Link: http://lkml.kernel.org/r/20161216144821.5183-29-aarcange@redhat.com
Signed-off-by: Mike Rapoport 
Signed-off-by: Andrea Arcangeli 
Cc: "Dr. David Alan Gilbert" 
Cc: Hillf Danton 
Cc: Michael Rapoport 
Cc: Mike Kravetz 
Cc: Pavel Emelyanov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

shmem: split huge pages beyond i_size under memory pressure

2016-07-26T23:19:19+00:00

Even if user asked to allocate huge pages always (huge=always), we
should be able to free up some memory by splitting pages which are
partly byound i_size if memory presure comes or once we hit limit on
filesystem size (-o size=).

In order to do this we maintain per-superblock list of inodes, which
potentially have huge pages on the border of file size.

Per-fs shrinker can reclaim memory by splitting such pages.

If we hit -ENOSPC during shmem_getpage_gfp(), we try to split a page to
free up space on the filesystem and retry allocation if it succeed.

Link: http://lkml.kernel.org/r/1466021202-61880-37-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

thp: introduce CONFIG_TRANSPARENT_HUGE_PAGECACHE

2016-07-26T23:19:19+00:00

For file mappings, we don't deposit page tables on THP allocation
because it's not strictly required to implement split_huge_pmd(): we can
just clear pmd and let following page faults to reconstruct the page
table.

But Power makes use of deposited page table to address MMU quirk.

Let's hide THP page cache, including huge tmpfs, under separate config
option, so it can be forbidden on Power.

We can revert the patch later once solution for Power found.

Link: http://lkml.kernel.org/r/1466021202-61880-36-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov 
Cc: Aneesh Kumar K.V 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

khugepaged: add support of collapse for tmpfs/shmem pages

2016-07-26T23:19:19+00:00

This patch extends khugepaged to support collapse of tmpfs/shmem pages.
We share fair amount of infrastructure with anon-THP collapse.

Few design points:

  - First we are looking for VMA which can be suitable for mapping huge
    page;

  - If the VMA maps shmem file, the rest scan/collapse operations
    operates on page cache, not on page tables as in anon VMA case.

  - khugepaged_scan_shmem() finds a range which is suitable for huge
    page. The scan is lockless and shouldn't disturb system too much.

  - once the candidate for collapse is found, collapse_shmem() attempts
    to create a huge page:

      + scan over radix tree, making the range point to new huge page;

      + new huge page is not-uptodate, locked and freezed (refcount
        is 0), so nobody can touch them until we say so.

      + we swap in pages during the scan. khugepaged_scan_shmem()
        filters out ranges with more than khugepaged_max_ptes_swap
	swapped out pages. It's HPAGE_PMD_NR/8 by default.

      + old pages are isolated, unmapped and put to local list in case
        to be restored back if collapse failed.

  - if collapse succeed, we retract pte page tables from VMAs where huge
    pages mapping is possible. The huge page will be mapped as PMD on
    next minor fault into the range.

Link: http://lkml.kernel.org/r/1466021202-61880-35-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

shmem: add huge pages support

2016-07-26T23:19:19+00:00

Here's basic implementation of huge pages support for shmem/tmpfs.

It's all pretty streight-forward:

  - shmem_getpage() allcoates huge page if it can and try to inserd into
    radix tree with shmem_add_to_page_cache();

  - shmem_add_to_page_cache() puts the page onto radix-tree if there's
    space for it;

  - shmem_undo_range() removes huge pages, if it fully within range.
    Partial truncate of huge pages zero out this part of THP.

    This have visible effect on fallocate(FALLOC_FL_PUNCH_HOLE)
    behaviour. As we don't really create hole in this case,
    lseek(SEEK_HOLE) may have inconsistent results depending what
    pages happened to be allocated.

  - no need to change shmem_fault: core-mm will map an compound page as
    huge if VMA is suitable;

Link: http://lkml.kernel.org/r/1466021202-61880-30-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

shmem: get_unmapped_area align huge page

2016-07-26T23:19:19+00:00

Provide a shmem_get_unmapped_area method in file_operations, called at
mmap time to decide the mapping address.  It could be conditional on
CONFIG_TRANSPARENT_HUGEPAGE, but save #ifdefs in other places by making
it unconditional.

shmem_get_unmapped_area() first calls the usual mm->get_unmapped_area
(which we treat as a black box, highly dependent on architecture and
config and executable layout).  Lots of conditions, and in most cases it
just goes with the address that chose; but when our huge stars are
rightly aligned, yet that did not provide a suitable address, go back to
ask for a larger arena, within which to align the mapping suitably.

There have to be some direct calls to shmem_get_unmapped_area(), not via
the file_operations: because of the way shmem_zero_setup() is called to
create a shmem object late in the mmap sequence, when MAP_SHARED is
requested with MAP_ANONYMOUS or /dev/zero.  Though this only matters
when /proc/sys/vm/shmem_huge has been set.

Link: http://lkml.kernel.org/r/1466021202-61880-29-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Hugh Dickins 
Signed-off-by: Kirill A. Shutemov 

Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

shmem: prepare huge= mount option and sysfs knob

2016-07-26T23:19:19+00:00

This patch adds new mount option "huge=". It can have following values:

- "always":
Attempt to allocate huge pages every time we need a new page;

- "never":
Do not allocate huge pages;

- "within_size":
Only allocate huge page if it will be fully within i_size.
Also respect fadvise()/madvise() hints;

- "advise:
Only allocate huge pages if requested with fadvise()/madvise();

Default is "never" for now.

"mount -o remount,huge= /mountpoint" works fine after mount: remounting
huge=never will not attempt to break up huge pages at all, just stop
more from being allocated.

No new config option: put this under CONFIG_TRANSPARENT_HUGEPAGE, which
is the appropriate option to protect those who don't want the new bloat,
and with which we shall share some pmd code.

Prohibit the option when !CONFIG_TRANSPARENT_HUGEPAGE, just as mpol is
invalid without CONFIG_NUMA (was hidden in mpol_parse_str(): make it
explicit).

Allow enabling THP only if the machine has_transparent_hugepage().

But what about Shmem with no user-visible mount? SysV SHM, memfds,
shared anonymous mmaps (of /dev/zero or MAP_ANONYMOUS), GPU drivers' DRM
objects, Ashmem. Though unlikely to suit all usages, provide sysfs knob
/sys/kernel/mm/transparent_hugepage/shmem_enabled to experiment with
huge on those.

And allow shmem_enabled two further values:

- "deny":
For use in emergencies, to force the huge option off from
all mounts;
- "force":
Force the huge option on for all - very useful for testing;

Based on patch by Hugh Dickins.

Link: http://lkml.kernel.org/r/1466021202-61880-28-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds