linux-stable.git/fs/open.c, branch v5.16

Merge branch 'akpm' (patches from Andrew)

2021-11-06T21:08:17+00:00

Merge misc updates from Andrew Morton:
 "257 patches.

  Subsystems affected by this patch series: scripts, ocfs2, vfs, and
  mm (slab-generic, slab, slub, kconfig, dax, kasan, debug, pagecache,
  gup, swap, memcg, pagemap, mprotect, mremap, iomap, tracing, vmalloc,
  pagealloc, memory-failure, hugetlb, userfaultfd, vmscan, tools,
  memblock, oom-kill, hugetlbfs, migration, thp, readahead, nommu, ksm,
  vmstat, madvise, memory-hotplug, rmap, zsmalloc, highmem, zram,
  cleanups, kfence, and damon)"

* emailed patches from Andrew Morton : (257 commits)
  mm/damon: remove return value from before_terminate callback
  mm/damon: fix a few spelling mistakes in comments and a pr_debug message
  mm/damon: simplify stop mechanism
  Docs/admin-guide/mm/pagemap: wordsmith page flags descriptions
  Docs/admin-guide/mm/damon/start: simplify the content
  Docs/admin-guide/mm/damon/start: fix a wrong link
  Docs/admin-guide/mm/damon/start: fix wrong example commands
  mm/damon/dbgfs: add adaptive_targets list check before enable monitor_on
  mm/damon: remove unnecessary variable initialization
  Documentation/admin-guide/mm/damon: add a document for DAMON_RECLAIM
  mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM)
  selftests/damon: support watermarks
  mm/damon/dbgfs: support watermarks
  mm/damon/schemes: activate schemes based on a watermarks mechanism
  tools/selftests/damon: update for regions prioritization of schemes
  mm/damon/dbgfs: support prioritization weights
  mm/damon/vaddr,paddr: support pageout prioritization
  mm/damon/schemes: prioritize regions within the quotas
  mm/damon/selftests: support schemes quotas
  mm/damon/dbgfs: support quotas of schemes
  ...

mm, thp: fix incorrect unmap behavior for private pages

2021-11-06T20:30:41+00:00

When truncating pagecache on file THP, the private pages of a process
should not be unmapped mapping.  This incorrect behavior on a dynamic
shared libraries which will cause related processes to happen core dump.

A simple test for a DSO (Prerequisite is the DSO mapped in file THP):

    int main(int argc, char *argv[])
    {
	int fd;

	fd = open(argv[1], O_WRONLY);
	if (fd < 0) {
		perror("open");
	}

	close(fd);
	return 0;
    }

The test only to open a target DSO, and do nothing.  But this operation
will lead one or more process to happen core dump.  This patch mainly to
fix this bug.

Link: https://lkml.kernel.org/r/20211025092134.18562-3-rongwei.wang@linux.alibaba.com
Fixes: eb6ecbed0aa2 ("mm, thp: relax the VM_DENYWRITE constraint on file-backed THPs")
Signed-off-by: Rongwei Wang 
Tested-by: Xu Yu 
Cc: Matthew Wilcox (Oracle) 
Cc: Song Liu 
Cc: William Kucharski 
Cc: Hugh Dickins 
Cc: Yang Shi 
Cc: Mike Kravetz 
Cc: Collin Fijalkovich 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, thp: lock filemap when truncating page cache

2021-11-06T20:30:41+00:00

Patch series "fix two bugs for file THP".

This patch (of 2):

Transparent huge page has supported read-only non-shmem files.  The
file- backed THP is collapsed by khugepaged and truncated when written
(for shared libraries).

However, there is a race when multiple writers truncate the same page
cache concurrently.

In that case, subpage(s) of file THP can be revealed by find_get_entry
in truncate_inode_pages_range, which will trigger PageTail BUG_ON in
truncate_inode_page, as follows:

    page:000000009e420ff2 refcount:1 mapcount:0 mapping:0000000000000000 index:0x7ff pfn:0x50c3ff
    head:0000000075ff816d order:9 compound_mapcount:0 compound_pincount:0
    flags: 0x37fffe0000010815(locked|uptodate|lru|arch_1|head)
    raw: 37fffe0000000000 fffffe0013108001 dead000000000122 dead000000000400
    raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
    head: 37fffe0000010815 fffffe001066bd48 ffff000404183c20 0000000000000000
    head: 0000000000000600 0000000000000000 00000001ffffffff ffff000c0345a000
    page dumped because: VM_BUG_ON_PAGE(PageTail(page))
    ------------[ cut here ]------------
    kernel BUG at mm/truncate.c:213!
    Internal error: Oops - BUG: 0 [#1] SMP
    Modules linked in: xfs(E) libcrc32c(E) rfkill(E) ...
    CPU: 14 PID: 11394 Comm: check_madvise_d Kdump: ...
    Hardware name: ECS, BIOS 0.0.0 02/06/2015
    pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--)
    Call trace:
     truncate_inode_page+0x64/0x70
     truncate_inode_pages_range+0x550/0x7e4
     truncate_pagecache+0x58/0x80
     do_dentry_open+0x1e4/0x3c0
     vfs_open+0x38/0x44
     do_open+0x1f0/0x310
     path_openat+0x114/0x1dc
     do_filp_open+0x84/0x134
     do_sys_openat2+0xbc/0x164
     __arm64_sys_openat+0x74/0xc0
     el0_svc_common.constprop.0+0x88/0x220
     do_el0_svc+0x30/0xa0
     el0_svc+0x20/0x30
     el0_sync_handler+0x1a4/0x1b0
     el0_sync+0x180/0x1c0
    Code: aa0103e0 900061e1 910ec021 9400d300 (d4210000)

This patch mainly to lock filemap when one enter truncate_pagecache(),
avoiding truncating the same page cache concurrently.

Link: https://lkml.kernel.org/r/20211025092134.18562-1-rongwei.wang@linux.alibaba.com
Link: https://lkml.kernel.org/r/20211025092134.18562-2-rongwei.wang@linux.alibaba.com
Fixes: eb6ecbed0aa2 ("mm, thp: relax the VM_DENYWRITE constraint on file-backed THPs")
Signed-off-by: Xu Yu 
Signed-off-by: Rongwei Wang 
Suggested-by: Matthew Wilcox (Oracle) 
Tested-by: Song Liu 
Cc: Collin Fijalkovich 
Cc: Hugh Dickins 
Cc: Mike Kravetz 
Cc: William Kucharski 
Cc: Yang Shi 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

audit: add OPENAT2 record to list "how" info

2021-10-04T16:09:27+00:00

Since the openat2(2) syscall uses a struct open_how pointer to communicate
its parameters they are not usefully recorded by the audit SYSCALL record's
four existing arguments.

Add a new audit record type OPENAT2 that reports the parameters in its
third argument, struct open_how with fields oflag, mode and resolve.

The new record in the context of an event would look like:
time->Wed Mar 17 16:28:53 2021
type=PROCTITLE msg=audit(1616012933.531:184): proctitle=
  73797363616C6C735F66696C652F6F70656E617432002F746D702F61756469742D
  7465737473756974652D737641440066696C652D6F70656E617432
type=PATH msg=audit(1616012933.531:184): item=1 name="file-openat2"
  inode=29 dev=00:1f mode=0100600 ouid=0 ogid=0 rdev=00:00
  obj=unconfined_u:object_r:user_tmp_t:s0 nametype=CREATE
  cap_fp=0 cap_fi=0 cap_fe=0 cap_fver=0 cap_frootid=0
type=PATH msg=audit(1616012933.531:184):
  item=0 name="/root/rgb/git/audit-testsuite/tests"
  inode=25 dev=00:1f mode=040700 ouid=0 ogid=0 rdev=00:00
  obj=unconfined_u:object_r:user_tmp_t:s0 nametype=PARENT
  cap_fp=0 cap_fi=0 cap_fe=0 cap_fver=0 cap_frootid=0
type=CWD msg=audit(1616012933.531:184):
  cwd="/root/rgb/git/audit-testsuite/tests"
type=OPENAT2 msg=audit(1616012933.531:184):
  oflag=0100302 mode=0600 resolve=0xa
type=SYSCALL msg=audit(1616012933.531:184): arch=c000003e syscall=437
  success=yes exit=4 a0=3 a1=7ffe315f1c53 a2=7ffe315f1550 a3=18
  items=2 ppid=528 pid=540 auid=0 uid=0 gid=0 euid=0 suid=0
  fsuid=0 egid=0 sgid=0 fsgid=0 tty=ttyS0 ses=1 comm="openat2"
  exe="/root/rgb/git/audit-testsuite/tests/syscalls_file/openat2"
  subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
  key="testsuite-1616012933-bjAUcEPO"

Link: https://lore.kernel.org/r/d23fbb89186754487850367224b060e26f9b7181.1621363275.git.rgb@redhat.com
Signed-off-by: Richard Guy Briggs 
Acked-by: Christian Brauner 
[PM: tweak subject, wrap example, move AUDIT_OPENAT2 to 1337]
Signed-off-by: Paul Moore

fs: remove mandatory file locking support

2021-08-23T10:15:36+00:00

We added CONFIG_MANDATORY_FILE_LOCKING in 2015, and soon after turned it
off in Fedora and RHEL8. Several other distros have followed suit.

I've heard of one problem in all that time: Someone migrated from an
older distro that supported "-o mand" to one that didn't, and the host
had a fstab entry with "mand" in it which broke on reboot. They didn't
actually _use_ mandatory locking so they just removed the mount option
and moved on.

This patch rips out mandatory locking support wholesale from the kernel,
along with the Kconfig option and the Documentation file. It also
changes the mount code to ignore the "mand" mount option instead of
erroring out, and to throw a big, ugly warning.

Signed-off-by: Jeff Layton

Merge branch 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2021-07-03T18:41:14+00:00

Pull vfs name lookup updates from Al Viro:
 "Small namei.c patch series, mostly to simplify the rules for nameidata
  state. It's actually from the previous cycle - but I didn't post it
  for review in time...

  Changes visible outside of fs/namei.c: file_open_root() calling
  conventions change, some freed bits in LOOKUP_... space"

* 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  namei: make sure nd->depth is always valid
  teach set_nameidata() to handle setting the root as well
  take LOOKUP_{ROOT,ROOT_GRABBED,JUMPED} out of LOOKUP_... space
  switch file_open_root() to struct path

Merge branch 'akpm' (patches from Andrew)

2021-07-02T19:08:10+00:00

Merge more updates from Andrew Morton:
 "190 patches.

  Subsystems affected by this patch series: mm (hugetlb, userfaultfd,
  vmscan, kconfig, proc, z3fold, zbud, ras, mempolicy, memblock,
  migration, thp, nommu, kconfig, madvise, memory-hotplug, zswap,
  zsmalloc, zram, cleanups, kfence, and hmm), procfs, sysctl, misc,
  core-kernel, lib, lz4, checkpatch, init, kprobes, nilfs2, hfs,
  signals, exec, kcov, selftests, compress/decompress, and ipc"

* emailed patches from Andrew Morton : (190 commits)
  ipc/util.c: use binary search for max_idx
  ipc/sem.c: use READ_ONCE()/WRITE_ONCE() for use_global_lock
  ipc: use kmalloc for msg_queue and shmid_kernel
  ipc sem: use kvmalloc for sem_undo allocation
  lib/decompressors: remove set but not used variabled 'level'
  selftests/vm/pkeys: exercise x86 XSAVE init state
  selftests/vm/pkeys: refill shadow register after implicit kernel write
  selftests/vm/pkeys: handle negative sys_pkey_alloc() return code
  selftests/vm/pkeys: fix alloc_random_pkey() to make it really, really random
  kcov: add __no_sanitize_coverage to fix noinstr for all architectures
  exec: remove checks in __register_bimfmt()
  x86: signal: don't do sas_ss_reset() until we are certain that sigframe won't be abandoned
  hfsplus: report create_date to kstat.btime
  hfsplus: remove unnecessary oom message
  nilfs2: remove redundant continue statement in a while-loop
  kprobes: remove duplicated strong free_insn_page in x86 and s390
  init: print out unknown kernel parameters
  checkpatch: do not complain about positive return values starting with EPOLL
  checkpatch: improve the indented label test
  checkpatch: scripts/spdxcheck.py now requires python3
  ...

mm, thp: relax the VM_DENYWRITE constraint on file-backed THPs

2021-07-01T03:47:29+00:00

Transparent huge pages are supported for read-only non-shmem files, but
are only used for vmas with VM_DENYWRITE.  This condition ensures that
file THPs are protected from writes while an application is running
(ETXTBSY).  Any existing file THPs are then dropped from the page cache
when a file is opened for write in do_dentry_open().  Since sys_mmap
ignores MAP_DENYWRITE, this constrains the use of file THPs to vmas
produced by execve().

Systems that make heavy use of shared libraries (e.g.  Android) are unable
to apply VM_DENYWRITE through the dynamic linker, preventing them from
benefiting from the resultant reduced contention on the TLB.

This patch reduces the constraint on file THPs allowing use with any
executable mapping from a file not opened for write (see
inode_is_open_for_write()).  It also introduces additional conditions to
ensure that files opened for write will never be backed by file THPs.

Restricting the use of THPs to executable mappings eliminates the risk
that a read-only file later opened for write would encounter significant
latencies due to page cache truncation.

The ld linker flag '-z max-page-size=(hugepage size)' can be used to
produce executables with the necessary layout.  The dynamic linker must
map these file's segments at a hugepage size aligned vma for the mapping
to be backed with THPs.

Comparison of the performance characteristics of 4KB and 2MB-backed
libraries follows; the Android dex2oat tool was used to AOT compile an
example application on a single ARM core.

4KB Pages:
==========

count              event_name            # count / runtime
598,995,035,942    cpu-cycles            # 1.800861 GHz
 81,195,620,851    raw-stall-frontend    # 244.112 M/sec
347,754,466,597    iTLB-loads            # 1.046 G/sec
  2,970,248,900    iTLB-load-misses      # 0.854122% miss rate

Total test time: 332.854998 seconds.

2MB Pages:
==========

count              event_name            # count / runtime
592,872,663,047    cpu-cycles            # 1.800358 GHz
 76,485,624,143    raw-stall-frontend    # 232.261 M/sec
350,478,413,710    iTLB-loads            # 1.064 G/sec
    803,233,322    iTLB-load-misses      # 0.229182% miss rate

Total test time: 329.826087 seconds

A check of /proc/$(pidof dex2oat64)/smaps shows THPs in use:

/apex/com.android.art/lib64/libart.so
FilePmdMapped:      4096 kB

/apex/com.android.art/lib64/libart-compiler.so
FilePmdMapped:      2048 kB

Link: https://lkml.kernel.org/r/20210406000930.3455850-1-cfijalkovich@google.com
Signed-off-by: Collin Fijalkovich 
Acked-by: Hugh Dickins 
Reviewed-by: William Kucharski 
Acked-by: Song Liu 
Cc: Suren Baghdasaryan 
Cc: Hridya Valsaraju 
Cc: Kalesh Singh 
Cc: Tim Murray 
Cc: Matthew Wilcox 
Cc: Alexander Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

open: don't silently ignore unknown O-flags in openat2()

2021-05-28T15:44:37+00:00

The new openat2() syscall verifies that no unknown O-flag values are
set and returns an error to userspace if they are while the older open
syscalls like open() and openat() simply ignore unknown flag values:

  #define O_FLAG_CURRENTLY_INVALID (1 << 31)
  struct open_how how = {
          .flags = O_RDONLY | O_FLAG_CURRENTLY_INVALID,
          .resolve = 0,
  };

  /* fails */
  fd = openat2(-EBADF, "/dev/null", &how, sizeof(how));

  /* succeeds */
  fd = openat(-EBADF, "/dev/null", O_RDONLY | O_FLAG_CURRENTLY_INVALID);

However, openat2() silently truncates the upper 32 bits meaning:

  #define O_FLAG_CURRENTLY_INVALID_LOWER32 (1 << 31)
  #define O_FLAG_CURRENTLY_INVALID_UPPER32 (1 << 40)

  struct open_how how_lowe32 = {
          .flags = O_RDONLY | O_FLAG_CURRENTLY_INVALID_LOWER32,
  };

  struct open_how how_upper32 = {
          .flags = O_RDONLY | O_FLAG_CURRENTLY_INVALID_UPPER32,
  };

  /* fails */
  fd = openat2(-EBADF, "/dev/null", &how_lower32, sizeof(how_lower32));

  /* succeeds */
  fd = openat2(-EBADF, "/dev/null", &how_upper32, sizeof(how_upper32));

Fix this by preventing the immediate truncation in build_open_flags().

There's a snafu here though stripping FMODE_* directly from flags would
cause the upper 32 bits to be truncated as well due to integer promotion
rules since FMODE_* is unsigned int, O_* are signed ints (yuck).

In addition, struct open_flags currently defines flags to be 32 bit
which is reasonable. If we simply were to bump it to 64 bit we would
need to change a lot of code preemptively which doesn't seem worth it.
So simply add a compile-time check verifying that all currently known
O_* flags are within the 32 bit range and fail to build if they aren't
anymore.

This change shouldn't regress old open syscalls since they silently
truncate any unknown values anyway. It is a tiny semantic change for
openat2() but it is very unlikely people pass ing > 32 bit unknown flags
and the syscall is relatively new too.

Link: https://lore.kernel.org/r/20210528092417.3942079-3-brauner@kernel.org
Cc: Christoph Hellwig 
Cc: Aleksa Sarai 
Cc: Al Viro 
Cc: linux-fsdevel@vger.kernel.org
Reported-by: Richard Guy Briggs 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Aleksa Sarai 
Reviewed-by: Richard Guy Briggs 
Signed-off-by: Christian Brauner

switch file_open_root() to struct path

2021-04-07T17:56:43+00:00

... and provide file_open_root_mnt(), using the root of given mount.

Signed-off-by: Al Viro