linux-stable.git/include/linux/page-flags.h, branch v4.19.239

page-flags: fix a crash at SetPageError(THP_SWAP)

2020-03-25T07:06:13+00:00

commit d72520ad004a8ce18a6ba6cde317f0081b27365a upstream.

Commit bd4c82c22c36 ("mm, THP, swap: delay splitting THP after swapped
out") supported writing THP to a swap device but forgot to upgrade an
older commit df8c94d13c7e ("page-flags: define behavior of FS/IO-related
flags on compound pages") which could trigger a crash during THP
swapping out with DEBUG_VM_PGFLAGS=y,

  kernel BUG at include/linux/page-flags.h:317!

  page dumped because: VM_BUG_ON_PAGE(1 && PageCompound(page))
  page:fffff3b2ec3a8000 refcount:512 mapcount:0 mapping:000000009eb0338c index:0x7f6e58200 head:fffff3b2ec3a8000 order:9 compound_mapcount:0 compound_pincount:0
  anon flags: 0x45fffe0000d8454(uptodate|lru|workingset|owner_priv_1|writeback|head|reclaim|swapbacked)

  end_swap_bio_write()
    SetPageError(page)
      VM_BUG_ON_PAGE(1 && PageCompound(page))

  
  bio_endio+0x297/0x560
  dec_pending+0x218/0x430 [dm_mod]
  clone_endio+0xe4/0x2c0 [dm_mod]
  bio_endio+0x297/0x560
  blk_update_request+0x201/0x920
  scsi_end_request+0x6b/0x4b0
  scsi_io_completion+0x509/0x7e0
  scsi_finish_command+0x1ed/0x2a0
  scsi_softirq_done+0x1c9/0x1d0
  __blk_mqnterrupt+0xf/0x20
  

Fix by checking PF_NO_TAIL in those places instead.

Fixes: bd4c82c22c36 ("mm, THP, swap: delay splitting THP after swapped out")
Signed-off-by: Qian Cai 
Signed-off-by: Andrew Morton 
Reviewed-by: David Hildenbrand 
Acked-by: "Huang, Ying" 
Acked-by: Rafael Aquini 
Cc: 
Link: http://lkml.kernel.org/r/20200310235846.1319-1-cai@lca.pw
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: thp: handle page cache THP correctly in PageTransCompoundMap

2019-11-12T18:20:36+00:00

commit 169226f7e0d275c1879551f37484ef6683579a5c upstream.

We have a usecase to use tmpfs as QEMU memory backend and we would like
to take the advantage of THP as well.  But, our test shows the EPT is
not PMD mapped even though the underlying THP are PMD mapped on host.
The number showed by /sys/kernel/debug/kvm/largepage is much less than
the number of PMD mapped shmem pages as the below:

  7f2778200000-7f2878200000 rw-s 00000000 00:14 262232 /dev/shm/qemu_back_mem.mem.Hz2hSf (deleted)
  Size:            4194304 kB
  [snip]
  AnonHugePages:         0 kB
  ShmemPmdMapped:   579584 kB
  [snip]
  Locked:                0 kB

  cat /sys/kernel/debug/kvm/largepages
  12

And some benchmarks do worse than with anonymous THPs.

By digging into the code we figured out that commit 127393fbe597 ("mm:
thp: kvm: fix memory corruption in KVM with THP enabled") checks if
there is a single PTE mapping on the page for anonymous THP when setting
up EPT map.  But the _mapcount < 0 check doesn't work for page cache THP
since every subpage of page cache THP would get _mapcount inc'ed once it
is PMD mapped, so PageTransCompoundMap() always returns false for page
cache THP.  This would prevent KVM from setting up PMD mapped EPT entry.

So we need handle page cache THP correctly.  However, when page cache
THP's PMD gets split, kernel just remove the map instead of setting up
PTE map like what anonymous THP does.  Before KVM calls get_user_pages()
the subpages may get PTE mapped even though it is still a THP since the
page cache THP may be mapped by other processes at the mean time.

Checking its _mapcount and whether the THP has PTE mapped or not.
Although this may report some false negative cases (PTE mapped by other
processes), it looks not trivial to make this accurate.

With this fix /sys/kernel/debug/kvm/largepage would show reasonable
pages are PMD mapped by EPT as the below:

  7fbeaee00000-7fbfaee00000 rw-s 00000000 00:14 275464 /dev/shm/qemu_back_mem.mem.SKUvat (deleted)
  Size:            4194304 kB
  [snip]
  AnonHugePages:         0 kB
  ShmemPmdMapped:   557056 kB
  [snip]
  Locked:                0 kB

  cat /sys/kernel/debug/kvm/largepages
  271

And the benchmarks are as same as anonymous THPs.

[yang.shi@linux.alibaba.com: v4]
  Link: http://lkml.kernel.org/r/1571865575-42913-1-git-send-email-yang.shi@linux.alibaba.com
Link: http://lkml.kernel.org/r/1571769577-89735-1-git-send-email-yang.shi@linux.alibaba.com
Fixes: dd78fedde4b9 ("rmap: support file thp")
Signed-off-by: Yang Shi 
Reported-by: Gang Deng 
Tested-by: Gang Deng 
Suggested-by: Hugh Dickins 
Acked-by: Kirill A. Shutemov 
Cc: Andrea Arcangeli 
Cc: Matthew Wilcox 
Cc: 	[4.8+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: soft-offline: close the race against page allocation

2018-08-24T01:48:43+00:00

A process can be killed with SIGBUS(BUS_MCEERR_AR) when it tries to
allocate a page that was just freed on the way of soft-offline.  This is
undesirable because soft-offline (which is about corrected error) is
less aggressive than hard-offline (which is about uncorrected error),
and we can make soft-offline fail and keep using the page for good
reason like "system is busy."

Two main changes of this patch are:

- setting migrate type of the target page to MIGRATE_ISOLATE. As done
  in free_unref_page_commit(), this makes kernel bypass pcplist when
  freeing the page. So we can assume that the page is in freelist just
  after put_page() returns,

- setting PG_hwpoison on free page under zone->lock which protects
  freelists, so this allows us to avoid setting PG_hwpoison on a page
  that is decided to be allocated soon.

[akpm@linux-foundation.org: tweak set_hwpoison_free_buddy_page() comment]
Link: http://lkml.kernel.org/r/1531452366-11661-3-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi 
Reported-by: Xishi Qiu 
Tested-by: Mike Kravetz 
Cc: Michal Hocko 
Cc: 
Cc: Mike Kravetz 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: mark pages in use for page tables

2018-06-08T00:34:37+00:00

Define a new PageTable bit in the page_type and use it to mark pages in
use as page tables.  This can be helpful when debugging crashdumps or
analysing memory fragmentation.  Add a KPF flag to report these pages to
userspace and update page-types.c to interpret that flag.

Note that only pages currently accounted as NR_PAGETABLES are tracked as
PageTable; this does not include pgd/p4d/pud/pmd pages.  Those will be the
subject of a later patch.

Link: http://lkml.kernel.org/r/20180518194519.3820-4-willy@infradead.org
Signed-off-by: Matthew Wilcox 
Acked-by: Kirill A. Shutemov 
Acked-by: Vlastimil Babka 
Cc: Christoph Lameter 
Cc: Dave Hansen 
Cc: Jérôme Glisse 
Cc: Lai Jiangshan 
Cc: Martin Schwidefsky 
Cc: Pekka Enberg 
Cc: Randy Dunlap 
Cc: Andrey Ryabinin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: split page_type out from _mapcount

2018-06-08T00:34:37+00:00

We're already using a union of many fields here, so stop abusing the
_mapcount and make page_type its own field.  That implies renaming some of
the machinery that creates PageBuddy, PageBalloon and PageKmemcg; bring
back the PG_buddy, PG_balloon and PG_kmemcg names.

As suggested by Kirill, make page_type a bitmask.  Because it starts out
life as -1 (thanks to sharing the storage with _mapcount), setting a page
flag means clearing the appropriate bit.  This gives us space for probably
twenty or so extra bits (depending how paranoid we want to be about
_mapcount underflow).

Link: http://lkml.kernel.org/r/20180518194519.3820-3-willy@infradead.org
Signed-off-by: Matthew Wilcox 
Acked-by: Kirill A. Shutemov 
Acked-by: Vlastimil Babka 
Cc: Christoph Lameter 
Cc: Dave Hansen 
Cc: Jérôme Glisse 
Cc: Lai Jiangshan 
Cc: Martin Schwidefsky 
Cc: Pekka Enberg 
Cc: Randy Dunlap 
Cc: Andrey Ryabinin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: uninitialized struct page poisoning sanity checking

2018-04-06T04:36:25+00:00

During boot we poison struct page memory in order to ensure that no one
is accessing this memory until the struct pages are initialized in
__init_single_page().

This patch adds more scrutiny to this checking by making sure that flags
do not equal the poison pattern when they are accessed.  The pattern is
all ones.

Since node id is also stored in struct page, and may be accessed quite
early, we add this enforcement into page_to_nid() function as well.
Note, this is applicable only when NODE_NOT_IN_PAGE_FLAGS=n

[pasha.tatashin@oracle.com: v4]
  Link: http://lkml.kernel.org/r/20180215165920.8570-4-pasha.tatashin@oracle.com
Link: http://lkml.kernel.org/r/20180213193159.14606-4-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin 
Reviewed-by: Ingo Molnar 
Acked-by: Michal Hocko 
Cc: Baoquan He 
Cc: Bharata B Rao 
Cc: Daniel Jordan 
Cc: Dan Williams 
Cc: Greg Kroah-Hartman 
Cc: "H. Peter Anvin" 
Cc: Kirill A. Shutemov 
Cc: Mel Gorman 
Cc: Steven Sistare 
Cc: Thomas Gleixner 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: remove PG_highmem description

2018-02-01T01:18:40+00:00

Commit cbe37d093707 ("[PATCH] mm: remove PG_highmem") removed PG_highmem
to save a page flag.  So the description of PG_highmem is no longer
needed.

Link: http://lkml.kernel.org/r/1517391212-2950-1-git-send-email-miles.chen@mediatek.com
Signed-off-by: Miles Chen 
Acked-by: Michal Hocko 
Reviewed-by: Andrew Morton 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, arch: remove empty_bad_page*

2017-11-16T02:21:03+00:00

empty_bad_page() and empty_bad_pte_table() seem to be relics from old
days which is not used by any code for a long time.  I have tried to
find when exactly but this is not really all that straightforward due to
many code movements - traces disappear around 2.4 times.

Anyway no code really references neither empty_bad_page nor
empty_bad_pte_table.  We only allocate the storage which is not used by
anybody so remove them.

Link: http://lkml.kernel.org/r/20171004150045.30755-1-mhocko@kernel.org
Signed-off-by: Michal Hocko 
Acked-by: Ralf Baechle 
Acked-by: Ingo Molnar 
Cc: Yoshinori Sato 
Cc: David Howells 
Cc: Rich Felker 
Cc: Jeff Dike 
Cc: Richard Weinberger 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

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

mm: test code to write THP to swap device as a whole

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

To support delay splitting THP (Transparent Huge Page) after swapped
out, we need to enhance swap writing code to support to write a THP as a
whole.  This will improve swap write IO performance.

As Ming Lei  pointed out, this should be based on
multipage bvec support, which hasn't been merged yet.  So this patch is
only for testing the functionality of the other patches in the series.
And will be reimplemented after multipage bvec support is merged.

Link: http://lkml.kernel.org/r/20170724051840.2309-7-ying.huang@intel.com
Signed-off-by: "Huang, Ying" 
Cc: "Kirill A . Shutemov" 
Cc: Andrea Arcangeli 
Cc: Dan Williams 
Cc: Hugh Dickins 
Cc: Jens Axboe 
Cc: Johannes Weiner 
Cc: Michal Hocko 
Cc: Minchan Kim 
Cc: Rik van Riel 
Cc: Ross Zwisler  [for brd.c, zram_drv.c, pmem.c]
Cc: Shaohua Li 
Cc: Vishal L Verma 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds