linux.git/tools/include/uapi/linux/fs.h, branch v7.3-rc2

mm/pagemap: add PAGE_IS_ACCESSED for RWP tracking

2026-08-05T02:18:38+00:00

PAGEMAP_SCAN already reports PAGE_IS_WRITTEN from the inverted uffd PTE
bit, targeting the UFFDIO_WRITEPROTECT workflow.  UFFDIO_RWPROTECT reuses
the same PTE bit as a marker for read-write protection, but "has been
written" and "has been accessed" are distinct semantic signals — they
happen to share one PTE bit today only because the two implementations
share infrastructure.

Give RWP its own pagemap category so the UAPI does not conflate them:

  PAGE_IS_WRITTEN   reported on VM_UFFD_WP VMAs,  !pte_uffd(pte)
  PAGE_IS_ACCESSED  reported on VM_UFFD_RWP VMAs, !pte_uffd(pte)

Both still read the same PTE bit today, but each is scoped to the VMA
whose registered mode makes the bit meaningful.  If a future
implementation moves RWP to a separate PTE bit, only PAGE_IS_ACCESSED
switches over.

This is a UAPI narrowing.  Outside VM_UFFD_WP VMAs the uffd bit is always
clear, so PAGEMAP_SCAN used to flag PAGE_IS_WRITTEN on every present PTE
there — a meaningless duplicate of PAGE_IS_PRESENT.  Now PAGE_IS_WRITTEN
fires only inside VM_UFFD_WP VMAs.

pagemap_hugetlb_category() now takes the vma like its PTE/PMD peers.

Link: https://lore.kernel.org/20260708111417.173443-12-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau 
Assisted-by: Claude:claude-opus-4-6
Acked-by: Mike Rapoport (Microsoft) 
Cc: Andrea Arcangeli 
Cc: David Hildenbrand 
Cc: James Houghton 
Cc: Jonathan Corbet 
Cc: Liam Howlett 
Cc: Lorenzo Stoakes 
Cc: Paolo Bonzini 
Cc: Peter Xu 
Cc: Sean Christopherson 
Cc: SeongJae Park 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Cc: Zi Yan 
Signed-off-by: Andrew Morton

tools headers UAPI: sync linux/fs.h with the kernel sources

2025-05-12T00:48:16+00:00

Required for a new PAGEMAP_SCAN test to verify guard region reporting.

Link: https://lkml.kernel.org/r/20250324065328.107678-3-avagin@google.com
Signed-off-by: Andrei Vagin 
Reviewed-by: Lorenzo Stoakes 
Cc: David Hildenbrand 
Cc: Jonathan Corbet 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton

tools: sync uapi/linux/fs.h header into tools subdir

2024-07-12T22:52:12+00:00

We need this UAPI header in tools/include subdirectory for using it from
BPF selftests.

Link: https://lkml.kernel.org/r/20240627170900.1672542-6-andrii@kernel.org
Signed-off-by: Andrii Nakryiko 
Acked-by: Liam R. Howlett 
Cc: Alexey Dobriyan 
Cc: Al Viro 
Cc: Christian Brauner 
Cc: Greg Kroah-Hartman 
Cc: Mike Rapoport (IBM) 
Cc: Suren Baghdasaryan 
Cc: Andi Kleen 
Cc: Arnd Bergmann 
Cc: Stephen Rothwell 
Signed-off-by: Andrew Morton

selftests/mm: fix vm_util.c build failures: add snapshot of fs.h

2024-07-04T02:30:07+00:00

On Ubuntu 23.04, on a clean git tree, the selftests/mm build fails due 10
or 20 missing items, all of which are found in fs.h, which is created via
"make headers".  However, as per [1], the idea is to stop requiring "make
headers", and instead, take a snapshot of the files and check them in.

Here are a few of the build errors:

vm_util.c:34:21: error: variable has incomplete type 'struct pm_scan_arg'
        struct pm_scan_arg arg;
...
vm_util.c:45:28: error: use of undeclared identifier 'PAGE_IS_WPALLOWED'
...
vm_util.c:55:21: error: variable has incomplete type 'struct page_region'
...
vm_util.c:105:20: error: use of undeclared identifier 'PAGE_IS_SOFT_DIRTY'

To fix this, add fs.h, taken from a snapshot of ./usr/include/linux/fs.h
after running "make headers".

[1] commit e076eaca5906 ("selftests: break the dependency upon local
header files")

Link: https://lkml.kernel.org/r/20240618022422.804305-5-jhubbard@nvidia.com
Signed-off-by: John Hubbard 
Acked-by: David Hildenbrand 
Cc: Andrei Vagin 
Cc: Axel Rasmussen 
Cc: Christian Brauner 
Cc: Jeff Xu 
Cc: Kees Cook 
Cc: Kent Overstreet 
Cc: Liam R. Howlett 
Cc: Muhammad Usama Anjum 
Cc: Peter Xu 
Cc: Rich Felker 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton

perf beauty: Move uapi/linux/fs.h copy out of the directory used to build perf

2024-03-21T13:41:27+00:00

It is mostly used only to generate string tables, not to build perf, so
move it to the tools/perf/trace/beauty/include/ hierarchy, that is used
just for scraping.

The only case where it was being used to build was in
tools/perf/trace/beauty/sync_file_range.c, because some older systems
doesn't have the SYNC_FILE_RANGE_WRITE_AND_WAIT define, just use the
system's linux/fs.h header instead, defining it if not available.

This is a something that should've have happened, as happened with the
linux/socket.h scrapper, do it now as Ian suggested while doing an
audit/refactor session in the headers used by perf.

No other tools/ living code uses it, just  coming from
either 'make install_headers' or from the system /usr/include/
directory.

Suggested-by: Ian Rogers 
Reviewed-by: Ian Rogers 
Cc: Adrian Hunter 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: https://lore.kernel.org/lkml/CAP-5=fWZVrpRufO4w-S4EcSi9STXcTAN2ERLwTSN7yrSSA-otQ@mail.gmail.com
Signed-off-by: Arnaldo Carvalho de Melo

fs/proc/task_mmu: report SOFT_DIRTY bits through the PAGEMAP_SCAN ioctl

2023-12-11T00:51:35+00:00

The PAGEMAP_SCAN ioctl returns information regarding page table entries. 
It is more efficient compared to reading pagemap files.  CRIU can start to
utilize this ioctl, but it needs info about soft-dirty bits to track
memory changes.

We are aware of a new method for tracking memory changes implemented in
the PAGEMAP_SCAN ioctl.  For CRIU, the primary advantage of this method is
its usability by unprivileged users.  However, it is not feasible to
transparently replace the soft-dirty tracker with the new one.  The main
problem here is userfault descriptors that have to be preserved between
pre-dump iterations.  It means criu continues supporting the soft-dirty
method to avoid breakage for current users.  The new method will be
implemented as a separate feature.

[avagin@google.com: update tools/include/uapi/linux/fs.h]
  Link: https://lkml.kernel.org/r/20231107164139.576046-1-avagin@google.com
Link: https://lkml.kernel.org/r/20231106220959.296568-1-avagin@google.com
Signed-off-by: Andrei Vagin 
Reviewed-by: Muhammad Usama Anjum 
Cc: Michał Mirosław 
Signed-off-by: Andrew Morton

tools headers UAPI: update linux/fs.h with the kernel sources

2023-10-18T21:34:13+00:00

New IOCTL and macros has been added in the kernel sources. Update the
tools header file as well.

Link: https://lkml.kernel.org/r/20230821141518.870589-5-usama.anjum@collabora.com
Signed-off-by: Muhammad Usama Anjum 
Cc: Alex Sierra 
Cc: Al Viro 
Cc: Andrei Vagin 
Cc: Axel Rasmussen 
Cc: Christian Brauner 
Cc: Cyrill Gorcunov 
Cc: Dan Williams 
Cc: David Hildenbrand 
Cc: Greg Kroah-Hartman 
Cc: Gustavo A. R. Silva 
Cc: "Liam R. Howlett" 
Cc: Matthew Wilcox 
Cc: Michal Miroslaw 
Cc: Michał Mirosław 
Cc: Mike Rapoport (IBM) 
Cc: Nadav Amit 
Cc: Pasha Tatashin 
Cc: Paul Gofman 
Cc: Peter Xu 
Cc: Shuah Khan 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Cc: Yang Shi 
Cc: Yun Zhou 
Signed-off-by: Andrew Morton

treewide: uapi: Replace zero-length arrays with flexible-array members

2022-06-28T19:26:05+00:00

There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a structure.
Kernel code should always use “flexible array members”[1] for these
cases. The older style of one-element or zero-length arrays should
no longer be used[2].

This code was transformed with the help of Coccinelle:
(linux-5.19-rc2$ spatch --jobs $(getconf _NPROCESSORS_ONLN) --sp-file script.cocci --include-headers --dir . > output.patch)

@@
identifier S, member, array;
type T1, T2;
@@

struct S {
  ...
  T1 member;
  T2 array[
- 0
  ];
};

-fstrict-flex-arrays=3 is coming and we need to land these changes
to prevent issues like these in the short future:

../fs/minix/dir.c:337:3: warning: 'strcpy' will always overflow; destination buffer has size 0,
but the source string has length 2 (including NUL byte) [-Wfortify-source]
		strcpy(de3->name, ".");
		^

Since these are all [0] to [] changes, the risk to UAPI is nearly zero. If
this breaks anything, we can use a union with a new member name.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/78
Build-tested-by: kernel test robot 
Link: https://lore.kernel.org/lkml/62b675ec.wKX6AOZ6cbE71vtF%25lkp@intel.com/
Acked-by: Dan Williams  # For ndctl.h
Signed-off-by: Gustavo A. R. Silva

tools headers UAPI: Sync linux/fs.h with the kernel sources

2021-09-11T19:14:53+00:00

To pick the change in:

  7957d93bf32bc211 ("block: add ioctl to read the disk sequence number")

It adds a new ioctl, but we are still not using that to generate tables
for 'perf trace', so no changes in tooling.

This silences this perf build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/fs.h' differs from latest version at 'include/uapi/linux/fs.h'
  diff -u tools/include/uapi/linux/fs.h include/uapi/linux/fs.h

Cc: Jens Axboe 
Cc: Matteo Croce 
Signed-off-by: Arnaldo Carvalho de Melo

tools headers UAPI: Sync linux/fs.h with the kernel sources

2021-05-21T19:00:31+00:00

To pick the trivial change in:

  63c8af5687f6b1b7 ("block: uapi: fix comment about block device ioctl")

This silences this perf build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/fs.h' differs from latest version at 'include/uapi/linux/fs.h'
  diff -u tools/include/uapi/linux/fs.h include/uapi/linux/fs.h

Cc: Damien Le Moal 
Cc: Jens Axboe 
Signed-off-by: Arnaldo Carvalho de Melo