Internal to mm/gup.c, require that get_user_pages_fast() and
__get_user_pages_fast() identify themselves, by setting FOLL_GET.  This is
required in order to be able to make decisions based on "FOLL_PIN, or
FOLL_GET, or both or neither are set", in upcoming patches.
Signed-off-by: NJohn Hubbard <jhubbard@nvidia.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NJan Kara <jack@suse.cz>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/20200211001536.1027652-6-jhubbard@nvidia.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In preparation for an upcoming patch, send gup flags args to two more
routines: put_compound_head(), and undo_dev_pagemap().
Signed-off-by: NJohn Hubbard <jhubbard@nvidia.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NJan Kara <jack@suse.cz>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/20200211001536.1027652-5-jhubbard@nvidia.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

An upcoming patch requires subtracting a large chunk of refcounts from a
page, and checking what the resulting refcount is.  This is a little
different than the usual "check for zero refcount" that many of the page
ref functions already do.  However, it is similar to a few other routines
that (like this one) are generally useful for things such as 1-based
refcounting.

Add page_ref_sub_return(), that subtracts a chunk of refcounts atomically,
and returns an atomic snapshot of the result.
Signed-off-by: NJohn Hubbard <jhubbard@nvidia.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NJan Kara <jack@suse.cz>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/20200211001536.1027652-4-jhubbard@nvidia.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A subsequent patch requires access to gup flags, so pass the flags
argument through to the __gup_device_* functions.

Also placate checkpatch.pl by shortening a nearby line.
Signed-off-by: NJohn Hubbard <jhubbard@nvidia.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NJan Kara <jack@suse.cz>
Reviewed-by: NJérôme Glisse <jglisse@redhat.com>
Reviewed-by: NIra Weiny <ira.weiny@intel.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/20200211001536.1027652-3-jhubbard@nvidia.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Patch series "mm/gup: track FOLL_PIN pages", v6.

This activates tracking of FOLL_PIN pages.  This is in support of fixing
the get_user_pages()+DMA problem described in [1]-[4].

FOLL_PIN support is now in the main linux tree.  However, the patch to use
FOLL_PIN to track pages was *not* submitted, because Leon saw an RDMA test
suite failure that involved (I think) page refcount overflows when huge
pages were used.

This patch definitively solves that kind of overflow problem, by adding an
exact pincount, for compound pages (of order > 1), in the 3rd struct page
of a compound page.  If available, that form of pincounting is used,
instead of the GUP_PIN_COUNTING_BIAS approach.  Thanks again to Jan Kara
for that idea.

Other interesting changes:

* dump_page(): added one, or two new things to report for compound
  pages: head refcount (for all compound pages), and map_pincount (for
  compound pages of order > 1).

* Documentation/core-api/pin_user_pages.rst: removed the "TODO" for the
  huge page refcount upper limit problems, and added notes about how it
  works now.  Also added a note about the dump_page() enhancements.

* Added some comments in gup.c and mm.h, to explain that there are two
  ways to count pinned pages: exact (for compound pages of order > 1) and
  fuzzy (GUP_PIN_COUNTING_BIAS: for all other pages).

============================================================
General notes about the tracking patch:

This is a prerequisite to solving the problem of proper interactions
between file-backed pages, and [R]DMA activities, as discussed in [1],
[2], [3], [4] and in a remarkable number of email threads since about
2017.  :)

In contrast to earlier approaches, the page tracking can be incrementally
applied to the kernel call sites that, until now, have been simply calling
get_user_pages() ("gup").  In other words, opt-in by changing from this:

    get_user_pages() (sets FOLL_GET)
    put_page()

to this:
    pin_user_pages() (sets FOLL_PIN)
    unpin_user_page()

============================================================
Future steps:

* Convert more subsystems from get_user_pages() to pin_user_pages().
  The first probably needs to be bio/biovecs, because any filesystem
  testing is too difficult without those in place.

* Change VFS and filesystems to respond appropriately when encountering
  dma-pinned pages.

* Work with Ira and others to connect this all up with file system
  leases.

[1] Some slow progress on get_user_pages() (Apr 2, 2019):
    https://lwn.net/Articles/784574/

[2] DMA and get_user_pages() (LPC: Dec 12, 2018):
    https://lwn.net/Articles/774411/

[3] The trouble with get_user_pages() (Apr 30, 2018):
    https://lwn.net/Articles/753027/

[4] LWN kernel index: get_user_pages()
    https://lwn.net/Kernel/Index/#Memory_management-get_user_pages

This patch (of 12):

An upcoming patch requires reusing the implementation of
get_user_pages_remote().  Split up get_user_pages_remote() into an outer
routine that checks flags, and an implementation routine that will be
reused.  This makes subsequent changes much easier to understand.

There should be no change in behavior due to this patch.
Signed-off-by: NJohn Hubbard <jhubbard@nvidia.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NJan Kara <jack@suse.cz>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/20200211001536.1027652-2-jhubbard@nvidia.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

 - These were never called PCG flags; they've been called FGP flags since
   their introduction in 2014.
 - The FGP_FOR_MMAP flag was misleadingly documented as if it was an
   alternative to FGP_CREAT instead of an option to it.
 - Rename the 'offset' parameter to 'index'.
 - Capitalisation, formatting, rewording.
Signed-off-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Link: http://lkml.kernel.org/r/20200318140253.6141-9-willy@infradead.orgSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

No in-tree users (proc, madvise, memcg, mincore) can be built as a module.
Signed-off-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Link: http://lkml.kernel.org/r/20200318140253.6141-8-willy@infradead.orgSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Dumping the page information in this circumstance helps for debugging.
Signed-off-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Link: http://lkml.kernel.org/r/20200318140253.6141-7-willy@infradead.orgSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This isn't just a random struct page, it's known to be a head page, and
calling it head makes the function better self-documenting.  The pgoff_t
is less confusing if it's named index instead of offset.  Also add a
couple of comments to explain why we're doing various things.
Signed-off-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: NPankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20200318140253.6141-3-willy@infradead.orgSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use VM_FAULT_OOM instead of indirecting through vmf_error(-ENOMEM).
Signed-off-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Link: http://lkml.kernel.org/r/20200318140253.6141-2-willy@infradead.orgSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The first argument of shrink_readahead_size_eio() is not used.  Hence
remove it from the function definition and from all the callers.
Signed-off-by: NSouptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1583868093-24342-1-git-send-email-jrdr.linux@gmail.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Mount failure issue happens under the scenario: Application forked dozens
of threads to mount the same number of cramfs images separately in docker,
but several mounts failed with high probability.  Mount failed due to the
checking result of the page(read from the superblock of loop dev) is not
uptodate after wait_on_page_locked(page) returned in function cramfs_read:

   wait_on_page_locked(page);
   if (!PageUptodate(page)) {
      ...
   }

The reason of the checking result of the page not uptodate: systemd-udevd
read the loopX dev before mount, because the status of loopX is Lo_unbound
at this time, so loop_make_request directly trigger the calling of io_end
handler end_buffer_async_read, which called SetPageError(page).  So It
caused the page can't be set to uptodate in function
end_buffer_async_read:

   if(page_uptodate && !PageError(page)) {
      SetPageUptodate(page);
   }

Then mount operation is performed, it used the same page which is just
accessed by systemd-udevd above, Because this page is not uptodate, it
will launch a actual read via submit_bh, then wait on this page by calling
wait_on_page_locked(page).  When the I/O of the page done, io_end handler
end_buffer_async_read is called, because no one cleared the page
error(during the whole read path of mount), which is caused by
systemd-udevd reading, so this page is still in "PageError" status, which
can't be set to uptodate in function end_buffer_async_read, then caused
mount failure.

But sometimes mount succeed even through systemd-udeved read loopX dev
just before, The reason is systemd-udevd launched other loopX read just
between step 3.1 and 3.2, the steps as below:

1, loopX dev default status is Lo_unbound;
2, systemd-udved read loopX dev (page is set to PageError);
3, mount operation
   1) set loopX status to Lo_bound;
   ==>systemd-udevd read loopX dev<==
   2) read loopX dev(page has no error)
   3) mount succeed

As the loopX dev status is set to Lo_bound after step 3.1, so the other
loopX dev read by systemd-udevd will go through the whole I/O stack, part
of the call trace as below:

   SYS_read
      vfs_read
          do_sync_read
              blkdev_aio_read
                 generic_file_aio_read
                     do_generic_file_read:
                        ClearPageError(page);
                        mapping->a_ops->readpage(filp, page);

here, mapping->a_ops->readpage() is blkdev_readpage.  In latest kernel,
some function name changed, the call trace as below:

   blkdev_read_iter
      generic_file_read_iter
         generic_file_buffered_read:
            /*
             * A previous I/O error may have been due to temporary
             * failures, eg. mutipath errors.
             * Pg_error will be set again if readpage fails.
             */
            ClearPageError(page);
            /* Start the actual read. The read will unlock the page*/
            error=mapping->a_ops->readpage(flip, page);

We can see ClearPageError(page) is called before the actual read,
then the read in step 3.2 succeed.

This patch is to add the calling of ClearPageError just before the actual
read of read path of cramfs mount.  Without the patch, the call trace as
below when performing cramfs mount:

   do_mount
      cramfs_read
         cramfs_blkdev_read
            read_cache_page
               do_read_cache_page:
                  filler(data, page);
                  or
                  mapping->a_ops->readpage(data, page);

With the patch, the call trace as below when performing mount:

   do_mount
      cramfs_read
         cramfs_blkdev_read
            read_cache_page:
               do_read_cache_page:
                  ClearPageError(page); <== new add
                  filler(data, page);
                  or
                  mapping->a_ops->readpage(data, page);

With the patch, mount operation trigger the calling of
ClearPageError(page) before the actual read, the page has no error if no
additional page error happen when I/O done.
Signed-off-by: NXianting Tian <xianting_tian@126.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Cc: Jan Kara <jack@suse.cz>
Cc: <yubin@h3c.com>
Link: http://lkml.kernel.org/r/1583318844-22971-1-git-send-email-xianting_tian@126.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There used to be a 'retry' label in between the two (identical) checks
when first introduced in commit f446daae ("mm: implement writeback
livelock avoidance using page tagging"), and later modified/updated in
commit 6e6938b6 ("writeback: introduce .tagged_writepages for the
WB_SYNC_NONE sync stage").

The label has been removed in commit 64081362 ("mm/page-writeback.c:
fix range_cyclic writeback vs writepages deadlock"), and the (identical)
checks are now present / performed immediately one after another.

So, remove/deduplicate the latter check, moving tag_pages_for_writeback()
into the former check before the 'tag' variable assignment, so it's clear
that it's not used in this (similarly-named) function call but only later
in pagevec_lookup_range_tag().
Signed-off-by: NMauricio Faria de Oliveira <mfo@canonical.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NIra Weiny <ira.weiny@intel.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>
Link: http://lkml.kernel.org/r/20200218221716.1648-1-mfo@canonical.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When handling a page fault, we drop mmap_sem to start async readahead so
that we don't block on IO submission with mmap_sem held.  However there's
no point to drop mmap_sem in case readahead is disabled.  Handle that case
to avoid pointless dropping of mmap_sem and retrying the fault.  This was
actually reported to block mlockall(MCL_CURRENT) indefinitely.

Fixes: 6b4c9f44 ("filemap: drop the mmap_sem for all blocking operations")
Reported-by: NMinchan Kim <minchan@kernel.org>
Reported-by: NRobert Stupp <snazy@gmx.de>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NMinchan Kim <minchan@kernel.org>
Link: http://lkml.kernel.org/r/20200212101356.30759-1-jack@suse.czSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Kmemleak could scan task stacks while plain writes happens to those stack
variables which could results in data races.  For example, in
sys_rt_sigaction and do_sigaction(), it could have plain writes in a
32-byte size.  Since the kmemleak does not care about the actual values of
a non-pointer and all do_sigaction() call sites only copy to stack
variables, just disable KCSAN for kmemleak to avoid annotating anything
outside Kmemleak just because Kmemleak scans everything.
Suggested-by: NMarco Elver <elver@google.com>
Signed-off-by: NQian Cai <cai@lca.pw>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NMarco Elver <elver@google.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Link: http://lkml.kernel.org/r/1583263716-25150-1-git-send-email-cai@lca.pwSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Clang warns:

  mm/kmemleak.c:1955:28: warning: array comparison always evaluates to a constant [-Wtautological-compare]
        if (__start_ro_after_init < _sdata || __end_ro_after_init > _edata)
                                  ^
  mm/kmemleak.c:1955:60: warning: array comparison always evaluates to a constant [-Wtautological-compare]
        if (__start_ro_after_init < _sdata || __end_ro_after_init > _edata)

These are not true arrays, they are linker defined symbols, which are just
addresses.  Using the address of operator silences the warning and does
not change the resulting assembly with either clang/ld.lld or gcc/ld
(tested with diff + objdump -Dr).
Suggested-by: NNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: NNathan Chancellor <natechancellor@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/895
Link: http://lkml.kernel.org/r/20200220051551.44000-1-natechancellor@gmail.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This reverts commit ad2c8144.

The function node_to_mem_node() was introduced by that commit for use in SLUB
on systems with memoryless nodes, but it turned out to be unreliable on some
architectures/configurations and a simpler solution exists than fixing it up.

Thus commit 0715e6c5 ("mm, slub: prevent kmalloc_node crashes and
memory leaks") removed the only user of node_to_mem_node() and we can
revert the commit that introduced the function.
Signed-off-by: NVlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: PUVICHAKRAVARTHY RAMACHANDRAN <puvichakravarthy@in.ibm.com>
Cc: Sachin Sant <sachinp@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20200320115533.9604-2-vbabka@suse.czSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In a recent discussion[1] with Vitaly Nikolenko and Silvio Cesare, it
became clear that moving the freelist pointer away from the edge of
allocations would likely improve the overall defensive posture of the
inline freelist pointer.  My benchmarks show no meaningful change to
performance (they seem to show it being faster), so this looks like a
reasonable change to make.

Instead of having the freelist pointer at the very beginning of an
allocation (offset 0) or at the very end of an allocation (effectively
offset -sizeof(void *) from the next allocation), move it away from the
edges of the allocation and into the middle.  This provides some
protection against small-sized neighboring overflows (or underflows), for
which the freelist pointer is commonly the target.  (Large or well
controlled overwrites are much more likely to attack live object contents,
instead of attempting freelist corruption.)

The vaunted kernel build benchmark, across 5 runs. Before:

	Mean: 250.05
	Std Dev: 1.85

and after, which appears mysteriously faster:

	Mean: 247.13
	Std Dev: 0.76

Attempts at running "sysbench --test=memory" show the change to be well in
the noise (sysbench seems to be pretty unstable here -- it's not really
measuring allocation).

Hackbench is more allocation-heavy, and while the std dev is above the
difference, it looks like may manifest as an improvement as well:

20 runs of "hackbench -g 20 -l 1000", before:

	Mean: 36.322
	Std Dev: 0.577

and after:

	Mean: 36.056
	Std Dev: 0.598

[1] https://twitter.com/vnik5287/status/1235113523098685440Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NChristoph Lameter <cl@linux.com>
Cc: Vitaly Nikolenko <vnik@duasynt.com>
Cc: Silvio Cesare <silvio.cesare@gmail.com>
Cc: Christoph Lameter <cl@linux.com>Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Link: http://lkml.kernel.org/r/202003051624.AAAC9AECC@keescookSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Under CONFIG_SLAB_FREELIST_HARDENED=y, the obfuscation was relatively weak
in that the ptr and ptr address were usually so close that the first XOR
would result in an almost entirely 0-byte value[1], leaving most of the
"secret" number ultimately being stored after the third XOR.  A single
blind memory content exposure of the freelist was generally sufficient to
learn the secret.

Add a swab() call to mix bits a little more.  This is a cheap way (1
cycle) to make attacks need more than a single exposure to learn the
secret (or to know _where_ the exposure is in memory).

kmalloc-32 freelist walk, before:

ptr              ptr_addr            stored value      secret
ffff90c22e019020@ffff90c22e019000 is 86528eb656b3b5bd (86528eb656b3b59d)
ffff90c22e019040@ffff90c22e019020 is 86528eb656b3b5fd (86528eb656b3b59d)
ffff90c22e019060@ffff90c22e019040 is 86528eb656b3b5bd (86528eb656b3b59d)
ffff90c22e019080@ffff90c22e019060 is 86528eb656b3b57d (86528eb656b3b59d)
ffff90c22e0190a0@ffff90c22e019080 is 86528eb656b3b5bd (86528eb656b3b59d)
...

after:

ptr              ptr_addr            stored value      secret
ffff9eed6e019020@ffff9eed6e019000 is 793d1135d52cda42 (86528eb656b3b59d)
ffff9eed6e019040@ffff9eed6e019020 is 593d1135d52cda22 (86528eb656b3b59d)
ffff9eed6e019060@ffff9eed6e019040 is 393d1135d52cda02 (86528eb656b3b59d)
ffff9eed6e019080@ffff9eed6e019060 is 193d1135d52cdae2 (86528eb656b3b59d)
ffff9eed6e0190a0@ffff9eed6e019080 is f93d1135d52cdac2 (86528eb656b3b59d)

[1] https://blog.infosectcbr.com.au/2020/03/weaknesses-in-linux-kernel-heap.html

Fixes: 2482ddec ("mm: add SLUB free list pointer obfuscation")
Reported-by: NSilvio Cesare <silvio.cesare@gmail.com>
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/202003051623.AF4F8CB@keescookSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There are slub_cpu_partial() and slub_set_cpu_partial() APIs to wrap
kmem_cache->cpu_partial.  This patch will use the two APIs to replace
kmem_cache->cpu_partial in slub code.
Signed-off-by: Nchenqiwu <chenqiwu@xiaomi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Link: http://lkml.kernel.org/r/1582079562-17980-1-git-send-email-qiwuchen55@gmail.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There are slub_percpu_partial() and slub_set_percpu_partial() APIs to wrap
kmem_cache->cpu_partial.  This patch will use the two to replace
cpu_slab->partial in slub code.
Signed-off-by: Nchenqiwu <chenqiwu@xiaomi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Link: http://lkml.kernel.org/r/1581951895-3038-1-git-send-email-qiwuchen55@gmail.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This notice fills my boot logs with scary-looking asterisks but doesn't
really tell me anything.  Let's just remove it; validation errors are
already reported separately, so this is just a redundant list of
filesystems.

$ dmesg | grep VALIDATE
[    0.306256] *** VALIDATE tmpfs ***
[    0.307422] *** VALIDATE proc ***
[    0.308355] *** VALIDATE cgroup ***
[    0.308741] *** VALIDATE cgroup2 ***
[    0.813256] *** VALIDATE bpf ***
[    0.815272] *** VALIDATE ramfs ***
[    0.815665] *** VALIDATE hugetlbfs ***
[    0.876970] *** VALIDATE nfs ***
[    0.877383] *** VALIDATE nfs4 ***
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NSeth Arnold <seth.arnold@canonical.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Link: http://lkml.kernel.org/r/202003061617.A8835CAAF@keescookSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

OCFS2 doesn't mind if memory reclaim makes I/Os happen; it just cares that
it won't be reentered, so it can use memalloc_nofs_save() instead of
memalloc_noio_save().
Signed-off-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Link: http://lkml.kernel.org/r/20200326200214.1102-1-willy@infradead.orgSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since snprintf() returns the would-be-output size instead of the actual
output size, the succeeding calls may go beyond the given buffer limit.
Fix it by replacing with scnprintf().
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Link: http://lkml.kernel.org/r/20200311093516.25300-1-tiwai@suse.deSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Under some conditions, the directory cannot be deleted.  The specific
scenarios are as follows: (for example, /mnt/ocfs2 is the mount point)

1. Create the /mnt/ocfs2/p_dir directory.  At this time, the i_nlink
   corresponding to the inode of the /mnt/ocfs2/p_dir directory is equal
   to 2.

2. During the process of creating the /mnt/ocfs2/p_dir/s_dir
   directory, if the call to the inc_nlink function in ocfs2_mknod
   succeeds, the functions such as ocfs2_init_acl,
   ocfs2_init_security_set, and ocfs2_dentry_attach_lock fail.  At this
   time, the i_nlink corresponding to the inode of the /mnt/ocfs2/p_dir
   directory is equal to 3, but /mnt/ocfs2/p_dir/s_dir is not added to the
   /mnt/ocfs2/p_dir directory entry.

3. Delete the /mnt/ocfs2/p_dir directory (rm -rf /mnt/ocfs2/p_dir).
   At this time, it is found that the i_nlink corresponding to the inode
   corresponding to the /mnt/ocfs2/p_dir directory is equal to 3.
   Therefore, the /mnt/ocfs2/p_dir directory cannot be deleted.
Signed-off-by: NJian wang <wangjian161@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NJun Piao <piaojun@huawei.com>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Link: http://lkml.kernel.org/r/a44f6666-bbc4-405e-0e6c-0f4e922eeef6@huawei.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The current codebase makes use of the zero-length array language extension
to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by this
change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied.  As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://urldefense.com/v3/__https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html__;!!GqivPVa7Brio!OKPotRhYhHbCG2kibo8Q6_6CuKaa28d_74h1svxyR6rbshrK2L_BdrQpNbvJWBWb40QCkg$
[2] https://urldefense.com/v3/__https://github.com/KSPP/linux/issues/21__;!!GqivPVa7Brio!OKPotRhYhHbCG2kibo8Q6_6CuKaa28d_74h1svxyR6rbshrK2L_BdrQpNbvJWBUhNn9M6g$
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Link: http://lkml.kernel.org/r/20200309202155.GA8432@embeddedorSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The current codebase makes use of the zero-length array language extension
to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by this
change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied.  As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://urldefense.com/v3/__https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html__;!!GqivPVa7Brio!OVOYL_CouISa5L1Lw-20EEFQntw6cKMx-j8UdY4z78uYgzKBUFcfpn50GaurvbV5v7YiUA$
[2] https://urldefense.com/v3/__https://github.com/KSPP/linux/issues/21__;!!GqivPVa7Brio!OVOYL_CouISa5L1Lw-20EEFQntw6cKMx-j8UdY4z78uYgzKBUFcfpn50GaurvbXs8Eh8eg$
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Link: http://lkml.kernel.org/r/20200309202016.GA8210@embeddedorSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The current codebase makes use of the zero-length array language extension
to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by this
change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied.  As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://urldefense.com/v3/__https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html__;!!GqivPVa7Brio!NzMr-YRl2zy-K3lwLVVatz7x0uD2z7-ykQag4GrGigxmfWU8TWzDy6xrkTiW3hYl00czlw$
[2] https://urldefense.com/v3/__https://github.com/KSPP/linux/issues/21__;!!GqivPVa7Brio!NzMr-YRl2zy-K3lwLVVatz7x0uD2z7-ykQag4GrGigxmfWU8TWzDy6xrkTiW3hYHG1nAnw$
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Link: http://lkml.kernel.org/r/20200309201907.GA8005@embeddedorSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The current codebase makes use of the zero-length array language extension
to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by this
change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied.  As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Link: http://lkml.kernel.org/r/20200213160244.GA6088@embeddedorSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Sparse reports warnings at ocfs2_refcount_cache_lock()
	and ocfs2_refcount_cache_unlock()

warning: context imbalance in ocfs2_refcount_cache_lock()
	- wrong count at exit
warning: context imbalance in ocfs2_refcount_cache_unlock()
	- unexpected unlock

The root cause is the missing annotation at ocfs2_refcount_cache_lock()
and at ocfs2_refcount_cache_unlock()

Add the missing __acquires(&rf->rf_lock) annotation to
ocfs2_refcount_cache_lock()

Add the missing __releases(&rf->rf_lock) annotation to
ocfs2_refcount_cache_unlock()
Signed-off-by: NJules Irenge <jbi.octave@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Link: http://lkml.kernel.org/r/20200224204130.18178-1-jbi.octave@gmail.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We don't need 'err' in these 2 places, better to remove them.
Signed-off-by: NAlex Shi <alex.shi@linux.alibaba.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: ChenGang <cg.chen@huawei.com>
Cc: Richard Fontana <rfontana@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1579577836-251879-1-git-send-email-alex.shi@linux.alibaba.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Correct annotation from "l_next_rec" to "l_next_free_rec"
Signed-off-by: NYan Wang <wangyan122@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NJun Piao <piaojun@huawei.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Link: http://lkml.kernel.org/r/5e76c953-3479-1280-023c-ad05e4c75608@huawei.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is no need to log twice in several functions.
Signed-off-by: NYan Wang <wangyan122@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NJun Piao <piaojun@huawei.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Link: http://lkml.kernel.org/r/77eec86a-f634-5b98-4f7d-0cd15185a37b@huawei.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This macro has been unused since it was introduced.
Signed-off-by: NAlex Shi <alex.shi@linux.alibaba.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Link: http://lkml.kernel.org/r/1579578203-254451-1-git-send-email-alex.shi@linux.alibaba.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This macro should be used.
Signed-off-by: NAlex Shi <alex.shi@linux.alibaba.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Link: http://lkml.kernel.org/r/1579577840-251956-1-git-send-email-alex.shi@linux.alibaba.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

O2HB_DEFAULT_BLOCK_BITS/DLM_THREAD_MAX_ASTS/DLM_MIGRATION_RETRY_MS and
OCFS2_MAX_RESV_WINDOW_BITS/OCFS2_MIN_RESV_WINDOW_BITS have been unused
since commit 66effd3c ("ocfs2/dlm: Do not migrate resource to a node
that is leaving the domain").
Signed-off-by: NAlex Shi <alex.shi@linux.alibaba.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: ChenGang <cg.chen@huawei.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Fontana <rfontana@redhat.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Link: http://lkml.kernel.org/r/1579577827-251796-1-git-send-email-alex.shi@linux.alibaba.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This macro is unused since commit ab09203e ("sysctl fs: Remove dead
binary sysctl support").
Signed-off-by: NAlex Shi <alex.shi@linux.alibaba.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Link: http://lkml.kernel.org/r/1579577812-251572-1-git-send-email-alex.shi@linux.alibaba.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Here are some of the more common spelling mistakes and typos that I've
found while fixing up spelling mistakes in the kernel since November 2019
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Joe Perches <joe@perches.com>
Link: http://lkml.kernel.org/r/20200313174946.228216-1-colin.king@canonical.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There are a few cases in the tree where "sysfs" is misspelled as "syfs".
Signed-off-by: NJonathan Neuschäfer <j.neuschaefer@gmx.ne>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Xiong <xndchn@gmail.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Chris Paterson <chris.paterson2@renesas.com>
Cc: Luca Ceresoli <luca@lucaceresoli.net>
Link: http://lkml.kernel.org/r/20200218152010.27349-1-j.neuschaefer@gmx.netSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Change a header to mandatory-y if both of the following are met:

[1] At least one architecture (except um) specifies it as generic-y in
    arch/*/include/asm/Kbuild

[2] Every architecture (except um) either has its own implementation
    (arch/*/include/asm/*.h) or specifies it as generic-y in
    arch/*/include/asm/Kbuild

This commit was generated by the following shell script.

----------------------------------->8-----------------------------------

arches=$(cd arch; ls -1 | sed -e '/Kconfig/d' -e '/um/d')

tmpfile=$(mktemp)

grep "^mandatory-y +=" include/asm-generic/Kbuild > $tmpfile

find arch -path 'arch/*/include/asm/Kbuild' |
	xargs sed -n 's/^generic-y += \(.*\)/\1/p' | sort -u |
while read header
do
	mandatory=yes

	for arch in $arches
	do
		if ! grep -q "generic-y += $header" arch/$arch/include/asm/Kbuild &&
			! [ -f arch/$arch/include/asm/$header ]; then
			mandatory=no
			break
		fi
	done

	if [ "$mandatory" = yes ]; then
		echo "mandatory-y += $header" >> $tmpfile

		for arch in $arches
		do
			sed -i "/generic-y += $header/d" arch/$arch/include/asm/Kbuild
		done
	fi

done

sed -i '/^mandatory-y +=/d' include/asm-generic/Kbuild

LANG=C sort $tmpfile >> include/asm-generic/Kbuild

----------------------------------->8-----------------------------------

One obvious benefit is the diff stat:

 25 files changed, 52 insertions(+), 557 deletions(-)

It is tedious to list generic-y for each arch that needs it.

So, mandatory-y works like a fallback default (by just wrapping
asm-generic one) when arch does not have a specific header
implementation.

See the following commits:

def3f7ce
a1b39bae

It is tedious to convert headers one by one, so I processed by a shell
script.
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Link: http://lkml.kernel.org/r/20200210175452.5030-1-masahiroy@kernel.orgSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>