linux.git/fs/proc/inode.c, branch for-next

proc: use __auto_type more

2024-09-17T08:11:20+00:00

Switch away from quite chatty declarations using typeof_member().

In theory this is faster to compile too because there is no macro
expansion and there is less type checking.

Link: https://lkml.kernel.org/r/81bf02fd-8724-4f4d-a2bb-c59620b7d716@p183
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton

mm: switch mm->get_unmapped_area() to a flag

2024-04-26T03:56:25+00:00

The mm_struct contains a function pointer *get_unmapped_area(), which is
set to either arch_get_unmapped_area() or arch_get_unmapped_area_topdown()
during the initialization of the mm.

Since the function pointer only ever points to two functions that are
named the same across all arch's, a function pointer is not really
required.  In addition future changes will want to add versions of the
functions that take additional arguments.  So to save a pointers worth of
bytes in mm_struct, and prevent adding additional function pointers to
mm_struct in future changes, remove it and keep the information about
which get_unmapped_area() to use in a flag.

Add the new flag to MMF_INIT_MASK so it doesn't get clobbered on fork by
mmf_init_flags().  Most MM flags get clobbered on fork.  In the
pre-existing behavior mm->get_unmapped_area() would get copied to the new
mm in dup_mm(), so not clobbering the flag preserves the existing behavior
around inheriting the topdown-ness.

Introduce a helper, mm_get_unmapped_area(), to easily convert code that
refers to the old function pointer to instead select and call either
arch_get_unmapped_area() or arch_get_unmapped_area_topdown() based on the
flag.  Then drop the mm->get_unmapped_area() function pointer.  Leave the
get_unmapped_area() pointer in struct file_operations alone.  The main
purpose of this change is to reorganize in preparation for future changes,
but it also converts the calls of mm->get_unmapped_area() from indirect
branches into a direct ones.

The stress-ng bigheap benchmark calls realloc a lot, which calls through
get_unmapped_area() in the kernel.  On x86, the change yielded a ~1%
improvement there on a retpoline config.

In testing a few x86 configs, removing the pointer unfortunately didn't
result in any actual size reductions in the compiled layout of mm_struct. 
But depending on compiler or arch alignment requirements, the change could
shrink the size of mm_struct.

Link: https://lkml.kernel.org/r/20240326021656.202649-3-rick.p.edgecombe@intel.com
Signed-off-by: Rick Edgecombe 
Acked-by: Dave Hansen 
Acked-by: Liam R. Howlett 
Reviewed-by: Kirill A. Shutemov 
Acked-by: Alexei Starovoitov 
Cc: Dan Williams 
Cc: Andy Lutomirski 
Cc: Aneesh Kumar K.V 
Cc: Borislav Petkov (AMD) 
Cc: Christophe Leroy 
Cc: Deepak Gupta 
Cc: Guo Ren 
Cc: Helge Deller 
Cc: H. Peter Anvin (Intel) 
Cc: Ingo Molnar 
Cc: "James E.J. Bottomley" 
Cc: Kees Cook 
Cc: Mark Brown 
Cc: Michael Ellerman 
Cc: Naveen N. Rao 
Cc: Nicholas Piggin 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton

proc: refactor pde_get_unmapped_area as prep

2024-04-26T03:56:25+00:00

Patch series "Cover a guard gap corner case", v4.

In working on x86’s shadow stack feature, I came across some limitations
around the kernel’s handling of guard gaps.  AFAICT these limitations
are not too important for the traditional stack usage of guard gaps, but
have bigger impact on shadow stack’s usage.  And now in addition to x86,
we have two other architectures implementing shadow stack like features
that plan to use guard gaps.  I wanted to see about addressing them, but I
have not worked on mmap() placement related code before, so would greatly
appreciate if people could take a look and point me in the right
direction.

The nature of the limitations of concern is as follows. In order to ensure 
guard gaps between mappings, mmap() would need to consider two things:
 1. That the new mapping isn’t placed in an any existing mapping’s guard
    gap.
 2. That the new mapping isn’t placed such that any existing mappings are
    not in *its* guard gaps
Currently mmap never considers (2), and (1) is not considered in some 
situations.

When not passing an address hint, or passing one without
MAP_FIXED_NOREPLACE, (1) is enforced.  With MAP_FIXED_NOREPLACE, (1) is
not enforced.  With MAP_FIXED, (1) is not considered, but this seems to be
expected since MAP_FIXED can already clobber existing mappings.  For
MAP_FIXED_NOREPLACE I would have guessed it should respect the guard gaps
of existing mappings, but it is probably a little ambiguous.

In this series I just tried to add enforcement of (2) for the normal (no
address hint) case and only for the newer shadow stack memory (not
stacks).  The reason is that with the no-address-hint situation, landing
next to a guard gap could come up naturally and so be more influencable by
attackers such that two shadow stacks could be adjacent without a guard
gap.  Where as the address-hint scenarios would require more control -
being able to call mmap() with specific arguments.  As for why not just
fix the other corner cases anyway, I thought it might have some greater
possibility of affecting existing apps.


This patch (of 14):

Future changes will perform a treewide change to remove the indirect
branch that is involved in calling mm->get_unmapped_area().  After doing
this, the function will no longer be able to be handled as a function
pointer.  To make the treewide change diff cleaner and easier to review,
refactor pde_get_unmapped_area() such that mm->get_unmapped_area() is
called without being stored in a local function pointer.  With this in
refactoring, follow on changes will be able to simply replace the call
site with a future function that calls it directly.

Link: https://lkml.kernel.org/r/20240326021656.202649-1-rick.p.edgecombe@intel.com
Link: https://lkml.kernel.org/r/20240326021656.202649-2-rick.p.edgecombe@intel.com
Signed-off-by: Rick Edgecombe 
Cc: Andy Lutomirski 
Cc: Borislav Petkov (AMD) 
Cc: Christophe Leroy 
Cc: Dave Hansen 
Cc: Deepak Gupta 
Cc: H. Peter Anvin (Intel) 
Cc: Ingo Molnar 
Cc: Kees Cook 
Cc: Kirill A. Shutemov 
Cc: Liam R. Howlett 
Cc: Mark Brown 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Alexei Starovoitov 
Cc: Aneesh Kumar K.V 
Cc: Dan Williams 
Cc: Guo Ren 
Cc: Helge Deller 
Cc: "James E.J. Bottomley" 
Cc: Michael Ellerman 
Cc: Naveen N. Rao 
Cc: Nicholas Piggin 
Signed-off-by: Andrew Morton

Merge tag 'vfs-6.9.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2024-03-11T16:38:17+00:00

Pull misc vfs updates from Christian Brauner:
"Misc features, cleanups, and fixes for vfs and individual filesystems.

Features:

- Support idmapped mounts for hugetlbfs.

- Add RWF_NOAPPEND flag for pwritev2(). This allows us to fix a bug
where the passed offset is ignored if the file is O_APPEND. The new
flag allows a caller to enforce that the offset is honored to
conform to posix even if the file was opened in append mode.

- Move i_mmap_rwsem in struct address_space to avoid false sharing
between i_mmap and i_mmap_rwsem.

- Convert efs, qnx4, and coda to use the new mount api.

- Add a generic is_dot_dotdot() helper that's used by various
filesystems and the VFS code instead of open-coding it multiple
times.

- Recently we've added stable offsets which allows stable ordering
when iterating directories exported through NFS on e.g., tmpfs
filesystems. Originally an xarray was used for the offset map but
that caused slab fragmentation issues over time. This switches the
offset map to the maple tree which has a dense mode that handles
this scenario a lot better. Includes tests.

- Finally merge the case-insensitive improvement series Gabriel has
been working on for a long time. This cleanly propagates case
insensitive operations through ->s_d_op which in turn allows us to
remove the quite ugly generic_set_encrypted_ci_d_ops() operations.
It also improves performance by trying a case-sensitive comparison
first and then fallback to case-insensitive lookup if that fails.
This also fixes a bug where overlayfs would be able to be mounted
over a case insensitive directory which would lead to all sort of
odd behaviors.

Cleanups:

- Make file_dentry() a simple accessor now that ->d_real() is
simplified because of the backing file work we did the last two
cycles.

- Use the dedicated file_mnt_idmap helper in ntfs3.

- Use smp_load_acquire/store_release() in the i_size_read/write
helpers and thus remove the hack to handle i_size reads in the
filemap code.

- The SLAB_MEM_SPREAD is a nop now. Remove it from various places in
fs/

- It's no longer necessary to perform a second built-in initramfs
unpack call because we retain the contents of the previous
extraction. Remove it.

- Now that we have removed various allocators kfree_rcu() always
works with kmem caches and kmalloc(). So simplify various places
that only use an rcu callback in order to handle the kmem cache
case.

- Convert the pipe code to use a lockdep comparison function instead
of open-coding the nesting making lockdep validation easier.

- Move code into fs-writeback.c that was located in a header but can
be made static as it's only used in that one file.

- Rewrite the alignment checking iterators for iovec and bvec to be
easier to read, and also significantly more compact in terms of
generated code. This saves 270 bytes of text on x86-64 (with
clang-18) and 224 bytes on arm64 (with gcc-13). In profiles it also
saves a bit of time for the same workload.

- Switch various places to use KMEM_CACHE instead of
kmem_cache_create().

- Use inode_set_ctime_to_ts() in inode_set_ctime_current()

- Use kzalloc() in name_to_handle_at() to avoid kernel infoleak.

- Various smaller cleanups for eventfds.

Fixes:

- Fix various comments and typos, and unneeded initializations.

- Fix stack allocation hack for clang in the select code.

- Improve dump_mapping() debug code on a best-effort basis.

- Fix build errors in various selftests.

- Avoid wrap-around instrumentation in various places.

- Don't allow user namespaces without an idmapping to be used for
idmapped mounts.

- Fix sysv sb_read() call.

- Fix fallback implementation of the get_name() export operation"

* tag 'vfs-6.9.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (70 commits)
hugetlbfs: support idmapped mounts
qnx4: convert qnx4 to use the new mount api
fs: use inode_set_ctime_to_ts to set inode ctime to current time
libfs: Drop generic_set_encrypted_ci_d_ops
ubifs: Configure dentry operations at dentry-creation time
f2fs: Configure dentry operations at dentry-creation time
ext4: Configure dentry operations at dentry-creation time
libfs: Add helper to choose dentry operations at mount-time
libfs: Merge encrypted_ci_dentry_ops and ci_dentry_ops
fscrypt: Drop d_revalidate once the key is added
fscrypt: Drop d_revalidate for valid dentries during lookup
fscrypt: Factor out a helper to configure the lookup dentry
ovl: Always reject mounting over case-insensitive directories
libfs: Attempt exact-match comparison first during casefolded lookup
efs: remove SLAB_MEM_SPREAD flag usage
jfs: remove SLAB_MEM_SPREAD flag usage
minix: remove SLAB_MEM_SPREAD flag usage
openpromfs: remove SLAB_MEM_SPREAD flag usage
proc: remove SLAB_MEM_SPREAD flag usage
qnx6: remove SLAB_MEM_SPREAD flag usage
...

proc: remove SLAB_MEM_SPREAD flag usage

2024-02-27T10:21:32+00:00

The SLAB_MEM_SPREAD flag used to be implemented in SLAB, which was
removed as of v6.8-rc1 (see [1]), so it became a dead flag since the
commit 16a1d968358a ("mm/slab: remove mm/slab.c and slab_def.h"). And
the series[1] went on to mark it obsolete explicitly to avoid confusion
for users. Here we can just remove all its users, which has no any
functional change.

Signed-off-by: Chengming Zhou 
Link: https://lore.kernel.org/all/20240223-slab-cleanup-flags-v2-1-02f1753e8303@suse.cz [1]
Link: https://lore.kernel.org/r/20240224135048.829987-1-chengming.zhou@linux.dev
Signed-off-by: Christian Brauner

procfs: move dropping pde and pid from ->evict_inode() to ->free_inode()

2024-02-25T07:10:32+00:00

that keeps both around until struct inode is freed, making access
to them safe from rcu-pathwalk

Acked-by: Christian Brauner 
Signed-off-by: Al Viro

Merge tag 'mm-nonmm-stable-2023-11-02-14-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2023-11-03T06:53:31+00:00

Pull non-MM updates from Andrew Morton:
 "As usual, lots of singleton and doubleton patches all over the tree
  and there's little I can say which isn't in the individual changelogs.

  The lengthier patch series are

   - 'kdump: use generic functions to simplify crashkernel reservation
     in arch', from Baoquan He. This is mainly cleanups and
     consolidation of the 'crashkernel=' kernel parameter handling

   - After much discussion, David Laight's 'minmax: Relax type checks in
     min() and max()' is here. Hopefully reduces some typecasting and
     the use of min_t() and max_t()

   - A group of patches from Oleg Nesterov which clean up and slightly
     fix our handling of reads from /proc/PID/task/... and which remove
     task_struct.thread_group"

* tag 'mm-nonmm-stable-2023-11-02-14-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (64 commits)
  scripts/gdb/vmalloc: disable on no-MMU
  scripts/gdb: fix usage of MOD_TEXT not defined when CONFIG_MODULES=n
  .mailmap: add address mapping for Tomeu Vizoso
  mailmap: update email address for Claudiu Beznea
  tools/testing/selftests/mm/run_vmtests.sh: lower the ptrace permissions
  .mailmap: map Benjamin Poirier's address
  scripts/gdb: add lx_current support for riscv
  ocfs2: fix a spelling typo in comment
  proc: test ProtectionKey in proc-empty-vm test
  proc: fix proc-empty-vm test with vsyscall
  fs/proc/base.c: remove unneeded semicolon
  do_io_accounting: use sig->stats_lock
  do_io_accounting: use __for_each_thread()
  ocfs2: replace BUG_ON() at ocfs2_num_free_extents() with ocfs2_error()
  ocfs2: fix a typo in a comment
  scripts/show_delta: add __main__ judgement before main code
  treewide: mark stuff as __ro_after_init
  fs: ocfs2: check status values
  proc: test /proc/${pid}/statm
  compiler.h: move __is_constexpr() to compiler.h
  ...

proc: save LOC by using while loop

2023-10-18T21:43:22+00:00

Use while loop instead of infinite loop with "break;".

Also move some variable to the inner scope where they belong.

Link: https://lkml.kernel.org/r/82c8f8e7-8ded-46ca-8857-e60b991d6205@p183
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton

proc: convert to new timestamp accessors

2023-10-18T12:08:26+00:00

Convert to using the new inode timestamp accessor functions.

Signed-off-by: Jeff Layton 
Link: https://lore.kernel.org/r/20231004185347.80880-59-jlayton@kernel.org
Signed-off-by: Christian Brauner

procfs: convert to ctime accessor functions

2023-07-24T08:30:03+00:00

In later patches, we're going to change how the inode's ctime field is
used. Switch to using accessor functions instead of raw accesses of
inode->i_ctime.

Acked-by: Luis Chamberlain 
Signed-off-by: Jeff Layton 
Reviewed-by: Jan Kara 
Message-Id: <20230705190309.579783-65-jlayton@kernel.org>
Signed-off-by: Christian Brauner