linux.git/tools/include/uapi/asm-generic, branch v6.6.131

tools headers UAPI: Sync files changed by new fchmodat2 and map_shadow_stack syscalls with the kernel sources

2023-09-13T11:24:51+00:00

To pick the changes in these csets:

  c35559f94ebc3e3b ("x86/shstk: Introduce map_shadow_stack syscall")
  78252deb023cf087 ("arch: Register fchmodat2, usually as syscall 452")

That add support for this new syscall in tools such as 'perf trace'.

For instance, this is now possible:

  # perf trace -v -e fchmodat*,map_shadow_stack --max-events=4
  Using CPUID AuthenticAMD-25-21-0
  Reusing "openat" BPF sys_enter augmenter for "fchmodat"
  event qualifier tracepoint filter: (common_pid != 3499340 && common_pid != 11259) && (id == 268 || id == 452 || id == 453)
  ^C#

  And it'll work as with other syscalls, for instance openat:

  # perf trace -e openat* --max-events=4
     0.000 ( 0.015 ms): systemd-oomd/1150 openat(dfd: CWD, filename: "/proc/meminfo", flags: RDONLY|CLOEXEC)    = 11
     0.068 ( 0.019 ms): systemd-oomd/1150 openat(dfd: CWD, filename: "/sys/fs/cgroup/user.slice/user-1001.slice/user@1001.service/memory.pressure", flags: RDONLY|CLOEXEC) = 11
     0.119 ( 0.008 ms): systemd-oomd/1150 openat(dfd: CWD, filename: "/sys/fs/cgroup/user.slice/user-1001.slice/user@1001.service/memory.current", flags: RDONLY|CLOEXEC) = 11
     0.138 ( 0.006 ms): systemd-oomd/1150 openat(dfd: CWD, filename: "/sys/fs/cgroup/user.slice/user-1001.slice/user@1001.service/memory.min", flags: RDONLY|CLOEXEC) = 11
  #

That is the filter expression attached to the raw_syscalls:sys_{enter,exit}
tracepoints.

  $ find tools/perf/arch/ -name "syscall*tbl" | xargs grep -E fchmodat\|sys_map_shadow_stack
  tools/perf/arch/mips/entry/syscalls/syscall_n64.tbl:258	n64	fchmodat			sys_fchmodat
  tools/perf/arch/mips/entry/syscalls/syscall_n64.tbl:452	n64	fchmodat2			sys_fchmodat2
  tools/perf/arch/powerpc/entry/syscalls/syscall.tbl:297	common	fchmodat			sys_fchmodat
  tools/perf/arch/powerpc/entry/syscalls/syscall.tbl:452	common	fchmodat2			sys_fchmodat2
  tools/perf/arch/s390/entry/syscalls/syscall.tbl:299  common	fchmodat		sys_fchmodat			sys_fchmodat
  tools/perf/arch/s390/entry/syscalls/syscall.tbl:452  common	fchmodat2		sys_fchmodat2			sys_fchmodat2
  tools/perf/arch/x86/entry/syscalls/syscall_64.tbl:268	common	fchmodat		sys_fchmodat
  tools/perf/arch/x86/entry/syscalls/syscall_64.tbl:452	common	fchmodat2		sys_fchmodat2
  tools/perf/arch/x86/entry/syscalls/syscall_64.tbl:453	64	map_shadow_stack	sys_map_shadow_stack
  $

  $ grep -Ew map_shadow_stack\|fchmodat2 /tmp/build/perf-tools/arch/x86/include/generated/asm/syscalls_64.c
	[452] = "fchmodat2",
	[453] = "map_shadow_stack",
  $

This addresses these perf build warnings:

  Warning: Kernel ABI header differences:
    diff -u tools/include/uapi/asm-generic/unistd.h include/uapi/asm-generic/unistd.h
    diff -u tools/perf/arch/x86/entry/syscalls/syscall_64.tbl arch/x86/entry/syscalls/syscall_64.tbl
    diff -u tools/perf/arch/powerpc/entry/syscalls/syscall.tbl arch/powerpc/kernel/syscalls/syscall.tbl
    diff -u tools/perf/arch/s390/entry/syscalls/syscall.tbl arch/s390/kernel/syscalls/syscall.tbl
    diff -u tools/perf/arch/mips/entry/syscalls/syscall_n64.tbl arch/mips/kernel/syscalls/syscall_n64.tbl

Cc: Adrian Hunter 
Cc: Christian Brauner 
Cc: Dave Hansen 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Palmer Dabbelt 
Cc: Rick Edgecombe 
Link: https://lore.kernel.org/lkml/ZP8bE7aXDBu%2Fdrak@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

tools headers UAPI: Sync files changed by new cachestat syscall with the kernel sources

2023-07-11T14:41:15+00:00

To pick the changes in these csets:

  cf264e1329fb0307 ("cachestat: implement cachestat syscall")

That add support for this new syscall in tools such as 'perf trace'.

For instance, this is now possible:

  # perf trace -e cachestat
  ^C[root@five ~]#
  # perf trace -v -e cachestat
  Using CPUID AuthenticAMD-25-21-0
  event qualifier tracepoint filter: (common_pid != 3163687 && common_pid != 3147) && (id == 451)
  mmap size 528384B
  ^C[root@five ~]

  # perf trace -v -e *stat* --max-events=10
  Using CPUID AuthenticAMD-25-21-0
  event qualifier tracepoint filter: (common_pid != 3163713 && common_pid != 3147) && (id == 4 || id == 5 || id == 6 || id == 136 || id == 137 || id == 138 || id == 262 || id == 332 || id == 451)
  mmap size 528384B
       0.000 ( 0.009 ms): Cache2 I/O/4544 statfs(pathname: 0x45635288, buf: 0x7f8745725b60)                     = 0
       0.012 ( 0.003 ms): Cache2 I/O/4544 newfstatat(dfd: CWD, filename: 0x45635288, statbuf: 0x7f874569d250)   = 0
       0.036 ( 0.002 ms): Cache2 I/O/4544 newfstatat(dfd: 138, filename: 0x541b7093, statbuf: 0x7f87457256f0, flag: 4096) = 0
       0.372 ( 0.006 ms): Cache2 I/O/4544 statfs(pathname: 0x45635288, buf: 0x7f8745725b10)                     = 0
       0.379 ( 0.003 ms): Cache2 I/O/4544 newfstatat(dfd: CWD, filename: 0x45635288, statbuf: 0x7f874569d250)   = 0
       0.390 ( 0.002 ms): Cache2 I/O/4544 newfstatat(dfd: 138, filename: 0x541b7093, statbuf: 0x7f87457256a0, flag: 4096) = 0
       0.609 ( 0.005 ms): Cache2 I/O/4544 statfs(pathname: 0x45635288, buf: 0x7f8745725b60)                     = 0
       0.615 ( 0.003 ms): Cache2 I/O/4544 newfstatat(dfd: CWD, filename: 0x45635288, statbuf: 0x7f874569d250)   = 0
       0.625 ( 0.002 ms): Cache2 I/O/4544 newfstatat(dfd: 138, filename: 0x541b7093, statbuf: 0x7f87457256f0, flag: 4096) = 0
       0.826 ( 0.005 ms): Cache2 I/O/4544 statfs(pathname: 0x45635288, buf: 0x7f8745725b10)                     = 0
  #

That is the filter expression attached to the raw_syscalls:sys_{enter,exit}
tracepoints.

  $ find tools/perf/arch/ -name "syscall*tbl" | xargs grep -w sys_cachestat
  tools/perf/arch/mips/entry/syscalls/syscall_n64.tbl:451	n64	cachestat			sys_cachestat
  tools/perf/arch/powerpc/entry/syscalls/syscall.tbl:451	common	cachestat			sys_cachestat
  tools/perf/arch/s390/entry/syscalls/syscall.tbl:451  common	cachestat		sys_cachestat			sys_cachestat
  tools/perf/arch/x86/entry/syscalls/syscall_64.tbl:451	common	cachestat		sys_cachestat
  $

  $ grep -w cachestat /tmp/build/perf-tools/arch/x86/include/generated/asm/syscalls_64.c
  	[451] = "cachestat",
  $

This addresses these perf build warnings:

Warning: Kernel ABI header differences:
  diff -u tools/include/uapi/asm-generic/unistd.h include/uapi/asm-generic/unistd.h
  diff -u tools/include/uapi/linux/mman.h include/uapi/linux/mman.h
  diff -u tools/perf/arch/x86/entry/syscalls/syscall_64.tbl arch/x86/entry/syscalls/syscall_64.tbl
  diff -u tools/perf/arch/powerpc/entry/syscalls/syscall.tbl arch/powerpc/kernel/syscalls/syscall.tbl
  diff -u tools/perf/arch/s390/entry/syscalls/syscall.tbl arch/s390/kernel/syscalls/syscall.tbl
  diff -u tools/perf/arch/mips/entry/syscalls/syscall_n64.tbl arch/mips/kernel/syscalls/syscall_n64.tbl

Cc: Adrian Hunter 
Cc: Andrew Morton 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Nhat Pham 
Link: https://lore.kernel.org/lkml/ZK1pVBJpbjujJNJW@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

Merge tag 'asm-generic-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

2023-07-06T17:06:04+00:00

Pull asm-generic updates from Arnd Bergmann:
 "These are cleanups for architecture specific header files:

   - the comments in include/linux/syscalls.h have gone out of sync and
     are really pointless, so these get removed

   - The asm/bitsperlong.h header no longer needs to be architecture
     specific on modern compilers, so use a generic version for newer
     architectures that use new enough userspace compilers

   - A cleanup for virt_to_pfn/virt_to_bus to have proper type checking,
     forcing the use of pointers"

* tag 'asm-generic-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  syscalls: Remove file path comments from headers
  tools arch: Remove uapi bitsperlong.h of hexagon and microblaze
  asm-generic: Unify uapi bitsperlong.h for arm64, riscv and loongarch
  m68k/mm: Make pfn accessors static inlines
  arm64: memory: Make virt_to_pfn() a static inline
  ARM: mm: Make virt_to_pfn() a static inline
  asm-generic/page.h: Make pfn accessors static inlines
  xen/netback: Pass (void *) to virt_to_page()
  netfs: Pass a pointer to virt_to_page()
  cifs: Pass a pointer to virt_to_page() in cifsglob
  cifs: Pass a pointer to virt_to_page()
  riscv: mm: init: Pass a pointer to virt_to_page()
  ARC: init: Pass a pointer to virt_to_pfn() in init
  m68k: Pass a pointer to virt_to_pfn() virt_to_page()
  fs/proc/kcore.c: Pass a pointer to virt_addr_valid()

syscalls: Remove file path comments from headers

2023-06-22T15:10:09+00:00

Source file locations for syscall definitions can change over a period
of time. File paths in comments get stale and are hard to maintain long
term. Also, their usefulness is questionable since it would be easier to
locate a syscall definition using the SYSCALL_DEFINEx() macro.

Remove all source file path comments from the syscall headers. Also,
equalize the uneven line spacing (some of which is introduced due to the
deletions).

Signed-off-by: Sohil Mehta 
Signed-off-by: Arnd Bergmann

asm-generic: Unify uapi bitsperlong.h for arm64, riscv and loongarch

2023-06-22T15:04:36+00:00

Now we specify the minimal version of GCC as 5.1 and Clang/LLVM as 11.0.0
in Documentation/process/changes.rst, __CHAR_BIT__ and __SIZEOF_LONG__ are
usable, it is probably fine to unify the definition of __BITS_PER_LONG as
(__CHAR_BIT__ * __SIZEOF_LONG__) in asm-generic uapi bitsperlong.h.

In order to keep safe and avoid regression, only unify uapi bitsperlong.h
for some archs such as arm64, riscv and loongarch which are using newer
toolchains that have the definitions of __CHAR_BIT__ and __SIZEOF_LONG__.

Suggested-by: Xi Ruoyao 
Link: https://lore.kernel.org/all/d3e255e4746de44c9903c4433616d44ffcf18d1b.camel@xry111.site/
Suggested-by: Arnd Bergmann 
Link: https://lore.kernel.org/linux-arch/a3a4f48a-07d4-4ed9-bc53-5d383428bdd2@app.fastmail.com/
Signed-off-by: Tiezhu Yang 
Signed-off-by: Arnd Bergmann

net: core: add getsockopt SO_PEERPIDFD

2023-06-12T09:45:50+00:00

Add SO_PEERPIDFD which allows to get pidfd of peer socket holder pidfd.
This thing is direct analog of SO_PEERCRED which allows to get plain PID.

Cc: "David S. Miller" 
Cc: Eric Dumazet 
Cc: Jakub Kicinski 
Cc: Paolo Abeni 
Cc: Leon Romanovsky 
Cc: David Ahern 
Cc: Arnd Bergmann 
Cc: Kees Cook 
Cc: Christian Brauner 
Cc: Kuniyuki Iwashima 
Cc: Lennart Poettering 
Cc: Luca Boccassi 
Cc: Daniel Borkmann 
Cc: Stanislav Fomichev 
Cc: bpf@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Reviewed-by: Christian Brauner 
Acked-by: Stanislav Fomichev 
Tested-by: Luca Boccassi 
Signed-off-by: Alexander Mikhalitsyn 
Reviewed-by: Eric Dumazet 
Signed-off-by: David S. Miller

scm: add SO_PASSPIDFD and SCM_PIDFD

2023-06-12T09:45:49+00:00

Implement SCM_PIDFD, a new type of CMSG type analogical to SCM_CREDENTIALS,
but it contains pidfd instead of plain pid, which allows programmers not
to care about PID reuse problem.

We mask SO_PASSPIDFD feature if CONFIG_UNIX is not builtin because
it depends on a pidfd_prepare() API which is not exported to the kernel
modules.

Idea comes from UAPI kernel group:
https://uapi-group.org/kernel-features/

Big thanks to Christian Brauner and Lennart Poettering for productive
discussions about this.

Cc: "David S. Miller" 
Cc: Eric Dumazet 
Cc: Jakub Kicinski 
Cc: Paolo Abeni 
Cc: Leon Romanovsky 
Cc: David Ahern 
Cc: Arnd Bergmann 
Cc: Kees Cook 
Cc: Christian Brauner 
Cc: Kuniyuki Iwashima 
Cc: Lennart Poettering 
Cc: Luca Boccassi 
Cc: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Tested-by: Luca Boccassi 
Reviewed-by: Kuniyuki Iwashima 
Reviewed-by: Christian Brauner 
Signed-off-by: Alexander Mikhalitsyn 
Reviewed-by: Eric Dumazet 
Signed-off-by: David S. Miller

open: return EINVAL for O_DIRECTORY | O_CREAT

2023-03-22T10:06:55+00:00

After a couple of years and multiple LTS releases we received a report
that the behavior of O_DIRECTORY | O_CREAT changed starting with v5.7.

On kernels prior to v5.7 combinations of O_DIRECTORY, O_CREAT, O_EXCL
had the following semantics:

(1) open("/tmp/d", O_DIRECTORY | O_CREAT)
    * d doesn't exist:                create regular file
    * d exists and is a regular file: ENOTDIR
    * d exists and is a directory:    EISDIR

(2) open("/tmp/d", O_DIRECTORY | O_CREAT | O_EXCL)
    * d doesn't exist:                create regular file
    * d exists and is a regular file: EEXIST
    * d exists and is a directory:    EEXIST

(3) open("/tmp/d", O_DIRECTORY | O_EXCL)
    * d doesn't exist:                ENOENT
    * d exists and is a regular file: ENOTDIR
    * d exists and is a directory:    open directory

On kernels since to v5.7 combinations of O_DIRECTORY, O_CREAT, O_EXCL
have the following semantics:

(1) open("/tmp/d", O_DIRECTORY | O_CREAT)
    * d doesn't exist:                ENOTDIR (create regular file)
    * d exists and is a regular file: ENOTDIR
    * d exists and is a directory:    EISDIR

(2) open("/tmp/d", O_DIRECTORY | O_CREAT | O_EXCL)
    * d doesn't exist:                ENOTDIR (create regular file)
    * d exists and is a regular file: EEXIST
    * d exists and is a directory:    EEXIST

(3) open("/tmp/d", O_DIRECTORY | O_EXCL)
    * d doesn't exist:                ENOENT
    * d exists and is a regular file: ENOTDIR
    * d exists and is a directory:    open directory

This is a fairly substantial semantic change that userspace didn't
notice until Pedro took the time to deliberately figure out corner
cases. Since no one noticed this breakage we can somewhat safely assume
that O_DIRECTORY | O_CREAT combinations are likely unused.

The v5.7 breakage is especially weird because while ENOTDIR is returned
indicating failure a regular file is actually created. This doesn't make
a lot of sense.

Time was spent finding potential users of this combination. Searching on
codesearch.debian.net showed that codebases often express semantical
expectations about O_DIRECTORY | O_CREAT which are completely contrary
to what our code has done and currently does.

The expectation often is that this particular combination would create
and open a directory. This suggests users who tried to use that
combination would stumble upon the counterintuitive behavior no matter
if pre-v5.7 or post v5.7 and quickly realize neither semantics give them
what they want. For some examples see the code examples in [1] to [3]
and the discussion in [4].

There are various ways to address this issue. The lazy/simple option
would be to restore the pre-v5.7 behavior and to just live with that bug
forever. But since there's a real chance that the O_DIRECTORY | O_CREAT
quirk isn't relied upon we should try to get away with murder(ing bad
semantics) first. If we need to Frankenstein pre-v5.7 behavior later so
be it.

So let's simply return EINVAL categorically for O_DIRECTORY | O_CREAT
combinations. In addition to cleaning up the old bug this also opens up
the possiblity to make that flag combination do something more intuitive
in the future.

Starting with this commit the following semantics apply:

(1) open("/tmp/d", O_DIRECTORY | O_CREAT)
    * d doesn't exist:                EINVAL
    * d exists and is a regular file: EINVAL
    * d exists and is a directory:    EINVAL

(2) open("/tmp/d", O_DIRECTORY | O_CREAT | O_EXCL)
    * d doesn't exist:                EINVAL
    * d exists and is a regular file: EINVAL
    * d exists and is a directory:    EINVAL

(3) open("/tmp/d", O_DIRECTORY | O_EXCL)
    * d doesn't exist:                ENOENT
    * d exists and is a regular file: ENOTDIR
    * d exists and is a directory:    open directory

One additional note, O_TMPFILE is implemented as:

    #define __O_TMPFILE    020000000
    #define O_TMPFILE      (__O_TMPFILE | O_DIRECTORY)
    #define O_TMPFILE_MASK (__O_TMPFILE | O_DIRECTORY | O_CREAT)

For older kernels it was important to return an explicit error when
O_TMPFILE wasn't supported. So O_TMPFILE requires that O_DIRECTORY is
raised alongside __O_TMPFILE. It also enforced that O_CREAT wasn't
specified. Since O_DIRECTORY | O_CREAT could be used to create a regular
allowing that combination together with __O_TMPFILE would've meant that
false positives were possible, i.e., that a regular file was created
instead of a O_TMPFILE. This could've been used to trick userspace into
thinking it operated on a O_TMPFILE when it wasn't.

Now that we block O_DIRECTORY | O_CREAT completely the check for O_CREAT
in the __O_TMPFILE branch via if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
can be dropped. Instead we can simply check verify that O_DIRECTORY is
raised via if (!(flags & O_DIRECTORY)) and explain this in two comments.

As Aleksa pointed out O_PATH is unaffected by this change since it
always returned EINVAL if O_CREAT was specified - with or without
O_DIRECTORY.

Link: https://lore.kernel.org/lkml/20230320071442.172228-1-pedro.falcato@gmail.com
Link: https://sources.debian.org/src/flatpak/1.14.4-1/subprojects/libglnx/glnx-dirfd.c/?hl=324#L324 [1]
Link: https://sources.debian.org/src/flatpak-builder/1.2.3-1/subprojects/libglnx/glnx-shutil.c/?hl=251#L251 [2]
Link: https://sources.debian.org/src/ostree/2022.7-2/libglnx/glnx-dirfd.c/?hl=324#L324 [3]
Link: https://www.openwall.com/lists/oss-security/2014/11/26/14 [4]
Reported-by: Pedro Falcato 
Cc: Aleksa Sarai 
Signed-off-by: Linus Torvalds 
Signed-off-by: Christian Brauner

mm/madvise: introduce MADV_COLLAPSE sync hugepage collapse

2022-09-12T03:25:46+00:00

This idea was introduced by David Rientjes[1].

Introduce a new madvise mode, MADV_COLLAPSE, that allows users to request
a synchronous collapse of memory at their own expense.

The benefits of this approach are:

* CPU is charged to the process that wants to spend the cycles for the
  THP
* Avoid unpredictable timing of khugepaged collapse

Semantics

This call is independent of the system-wide THP sysfs settings, but will
fail for memory marked VM_NOHUGEPAGE.  If the ranges provided span
multiple VMAs, the semantics of the collapse over each VMA is independent
from the others.  This implies a hugepage cannot cross a VMA boundary.  If
collapse of a given hugepage-aligned/sized region fails, the operation may
continue to attempt collapsing the remainder of memory specified.

The memory ranges provided must be page-aligned, but are not required to
be hugepage-aligned.  If the memory ranges are not hugepage-aligned, the
start/end of the range will be clamped to the first/last hugepage-aligned
address covered by said range.  The memory ranges must span at least one
hugepage-sized region.

All non-resident pages covered by the range will first be
swapped/faulted-in, before being internally copied onto a freshly
allocated hugepage.  Unmapped pages will have their data directly
initialized to 0 in the new hugepage.  However, for every eligible
hugepage aligned/sized region to-be collapsed, at least one page must
currently be backed by memory (a PMD covering the address range must
already exist).

Allocation for the new hugepage may enter direct reclaim and/or
compaction, regardless of VMA flags.  When the system has multiple NUMA
nodes, the hugepage will be allocated from the node providing the most
native pages.  This operation operates on the current state of the
specified process and makes no persistent changes or guarantees on how
pages will be mapped, constructed, or faulted in the future

Return Value

If all hugepage-sized/aligned regions covered by the provided range were
either successfully collapsed, or were already PMD-mapped THPs, this
operation will be deemed successful.  On success, process_madvise(2)
returns the number of bytes advised, and madvise(2) returns 0.  Else, -1
is returned and errno is set to indicate the error for the most-recently
attempted hugepage collapse.  Note that many failures might have occurred,
since the operation may continue to collapse in the event a single
hugepage-sized/aligned region fails.

	ENOMEM	Memory allocation failed or VMA not found
	EBUSY	Memcg charging failed
	EAGAIN	Required resource temporarily unavailable.  Try again
		might succeed.
	EINVAL	Other error: No PMD found, subpage doesn't have Present
		bit set, "Special" page no backed by struct page, VMA
		incorrectly sized, address not page-aligned, ...

Most notable here is ENOMEM and EBUSY (new to madvise) which are intended
to provide the caller with actionable feedback so they may take an
appropriate fallback measure.

Use Cases

An immediate user of this new functionality are malloc() implementations
that manage memory in hugepage-sized chunks, but sometimes subrelease
memory back to the system in native-sized chunks via MADV_DONTNEED;
zapping the pmd.  Later, when the memory is hot, the implementation could
madvise(MADV_COLLAPSE) to re-back the memory by THPs to regain hugepage
coverage and dTLB performance.  TCMalloc is such an implementation that
could benefit from this[2].

Only privately-mapped anon memory is supported for now, but additional
support for file, shmem, and HugeTLB high-granularity mappings[2] is
expected.  File and tmpfs/shmem support would permit:

* Backing executable text by THPs.  Current support provided by
  CONFIG_READ_ONLY_THP_FOR_FS may take a long time on a large system which
  might impair services from serving at their full rated load after
  (re)starting.  Tricks like mremap(2)'ing text onto anonymous memory to
  immediately realize iTLB performance prevents page sharing and demand
  paging, both of which increase steady state memory footprint.  With
  MADV_COLLAPSE, we get the best of both worlds: Peak upfront performance
  and lower RAM footprints.
* Backing guest memory by hugapages after the memory contents have been
  migrated in native-page-sized chunks to a new host, in a
  userfaultfd-based live-migration stack.

[1] https://lore.kernel.org/linux-mm/d098c392-273a-36a4-1a29-59731cdf5d3d@google.com/
[2] https://github.com/google/tcmalloc/tree/master/tcmalloc

[jrdr.linux@gmail.com: avoid possible memory leak in failure path]
  Link: https://lkml.kernel.org/r/20220713024109.62810-1-jrdr.linux@gmail.com
[zokeefe@google.com add missing kfree() to madvise_collapse()]
  Link: https://lore.kernel.org/linux-mm/20220713024109.62810-1-jrdr.linux@gmail.com/
  Link: https://lkml.kernel.org/r/20220713161851.1879439-1-zokeefe@google.com
[zokeefe@google.com: delay computation of hpage boundaries until use]]
  Link: https://lkml.kernel.org/r/20220720140603.1958773-4-zokeefe@google.com
Link: https://lkml.kernel.org/r/20220706235936.2197195-10-zokeefe@google.com
Signed-off-by: Zach O'Keefe 
Signed-off-by: "Souptick Joarder (HPE)" 
Suggested-by: David Rientjes 
Cc: Alex Shi 
Cc: Andrea Arcangeli 
Cc: Arnd Bergmann 
Cc: Axel Rasmussen 
Cc: Chris Kennelly 
Cc: Chris Zankel 
Cc: David Hildenbrand 
Cc: Helge Deller 
Cc: Hugh Dickins 
Cc: Ivan Kokshaysky 
Cc: James Bottomley 
Cc: Jens Axboe 
Cc: "Kirill A. Shutemov" 
Cc: Matthew Wilcox 
Cc: Matt Turner 
Cc: Max Filippov 
Cc: Miaohe Lin 
Cc: Michal Hocko 
Cc: Minchan Kim 
Cc: Pasha Tatashin 
Cc: Pavel Begunkov 
Cc: Peter Xu 
Cc: Rongwei Wang 
Cc: SeongJae Park 
Cc: Song Liu 
Cc: Thomas Bogendoerfer 
Cc: Vlastimil Babka 
Cc: Yang Shi 
Cc: Zi Yan 
Cc: Dan Carpenter 
Signed-off-by: Andrew Morton

Merge tag 'asm-generic-6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

2022-08-05T17:07:23+00:00

Pull asm-generic updates from Arnd Bergmann:
 "There are three independent sets of changes:

   - Sai Prakash Ranjan adds tracing support to the asm-generic version
     of the MMIO accessors, which is intended to help understand
     problems with device drivers and has been part of Qualcomm's vendor
     kernels for many years

   - A patch from Sebastian Siewior to rework the handling of IRQ stacks
     in softirqs across architectures, which is needed for enabling
     PREEMPT_RT

   - The last patch to remove the CONFIG_VIRT_TO_BUS option and some of
     the code behind that, after the last users of this old interface
     made it in through the netdev, scsi, media and staging trees"

* tag 'asm-generic-6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  uapi: asm-generic: fcntl: Fix typo 'the the' in comment
  arch/*/: remove CONFIG_VIRT_TO_BUS
  soc: qcom: geni: Disable MMIO tracing for GENI SE
  serial: qcom_geni_serial: Disable MMIO tracing for geni serial
  asm-generic/io: Add logging support for MMIO accessors
  KVM: arm64: Add a flag to disable MMIO trace for nVHE KVM
  lib: Add register read/write tracing support
  drm/meson: Fix overflow implicit truncation warnings
  irqchip/tegra: Fix overflow implicit truncation warnings
  coresight: etm4x: Use asm-generic IO memory barriers
  arm64: io: Use asm-generic high level MMIO accessors
  arch/*: Disable softirq stacks on PREEMPT_RT.