Pull overflow updates from Kees Cook:
 "This adds the new overflow checking helpers and adds them to the
  2-factor argument allocators. And this adds the saturating size
  helpers and does a treewide replacement for the struct_size() usage.
  Additionally this adds the overflow testing modules to make sure
  everything works.

  I'm still working on the treewide replacements for allocators with
  "simple" multiplied arguments:

     *alloc(a * b, ...) -> *alloc_array(a, b, ...)

  and

     *zalloc(a * b, ...) -> *calloc(a, b, ...)

  as well as the more complex cases, but that's separable from this
  portion of the series. I expect to have the rest sent before -rc1
  closes; there are a lot of messy cases to clean up.

  Summary:

   - Introduce arithmetic overflow test helper functions (Rasmus)

   - Use overflow helpers in 2-factor allocators (Kees, Rasmus)

   - Introduce overflow test module (Rasmus, Kees)

   - Introduce saturating size helper functions (Matthew, Kees)

   - Treewide use of struct_size() for allocators (Kees)"

* tag 'overflow-v4.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  treewide: Use struct_size() for devm_kmalloc() and friends
  treewide: Use struct_size() for vmalloc()-family
  treewide: Use struct_size() for kmalloc()-family
  device: Use overflow helpers for devm_kmalloc()
  mm: Use overflow helpers in kvmalloc()
  mm: Use overflow helpers in kmalloc_array*()
  test_overflow: Add memory allocation overflow tests
  overflow.h: Add allocation size calculation helpers
  test_overflow: Report test failures
  test_overflow: macrofy some more, do more tests for free
  lib: add runtime test of check_*_overflow functions
  compiler.h: enable builtin overflow checkers and add fallback code

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct foo {
    int stuff;
    void *entry[];
};

instance = kmalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL);

This patch makes the changes for kmalloc()-family (and kvmalloc()-family)
uses. It was done via automatic conversion with manual review for the
"CHECKME" non-standard cases noted below, using the following Coccinelle
script:

// pkey_cache = kmalloc(sizeof *pkey_cache + tprops->pkey_tbl_len *
//                      sizeof *pkey_cache->table, GFP_KERNEL);
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
identifier VAR, ELEMENT;
expression COUNT;
@@

- alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT), GFP)
+ alloc(struct_size(VAR, ELEMENT, COUNT), GFP)

// mr = kzalloc(sizeof(*mr) + m * sizeof(mr->map[0]), GFP_KERNEL);
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
identifier VAR, ELEMENT;
expression COUNT;
@@

- alloc(sizeof(*VAR) + COUNT * sizeof(VAR->ELEMENT[0]), GFP)
+ alloc(struct_size(VAR, ELEMENT, COUNT), GFP)

// Same pattern, but can't trivially locate the trailing element name,
// or variable name.
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
expression SOMETHING, COUNT, ELEMENT;
@@

- alloc(sizeof(SOMETHING) + COUNT * sizeof(ELEMENT), GFP)
+ alloc(CHECKME_struct_size(&SOMETHING, ELEMENT, COUNT), GFP)

Signed-off-by: Kees Cook <keescook@chromium.org>

Pull cgroup updates from Tejun Heo:

 - For cpustat, cgroup has a percpu hierarchical stat mechanism which
   propagates up the hierarchy lazily.

   This contains commits to factor out and generalize the mechanism so
   that it can be used for other cgroup stats too.

   The original intention was to update memcg stats to use it but memcg
   went for a different approach, so still the only user is cpustat. The
   factoring out and generalization still make sense and it's likely
   that this can be used for other purposes in the future.

 - cgroup uses kernfs_notify() (which uses fsnotify()) to inform user
   space of certain events. A rate limiting mechanism is added.

 - Other misc changes.

* 'for-4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: css_set_lock should nest inside tasklist_lock
  rdmacg: Convert to use match_string() helper
  cgroup: Make cgroup_rstat_updated() ready for root cgroup usage
  cgroup: Add memory barriers to plug cgroup_rstat_updated() race window
  cgroup: Add cgroup_subsys->css_rstat_flush()
  cgroup: Replace cgroup_rstat_mutex with a spinlock
  cgroup: Factor out and expose cgroup_rstat_*() interface functions
  cgroup: Reorganize kernel/cgroup/rstat.c
  cgroup: Distinguish base resource stat implementation from rstat
  cgroup: Rename stat to rstat
  cgroup: Rename kernel/cgroup/stat.c to kernel/cgroup/rstat.c
  cgroup: Limit event generation frequency
  cgroup: Explicitly remove core interface files

cgroup_enable_task_cg_lists() incorrectly nests non-irq-safe
tasklist_lock inside irq-safe css_set_lock triggering the following
lockdep warning.

  WARNING: possible irq lock inversion dependency detected
  4.17.0-rc1-00027-gb37d049 #6 Not tainted
  --------------------------------------------------------
  systemd/1 just changed the state of lock:
  00000000fe57773b (css_set_lock){..-.}, at: cgroup_free+0xf2/0x12a
  but this lock took another, SOFTIRQ-unsafe lock in the past:
   (tasklist_lock){.+.+}

  and interrupts could create inverse lock ordering between them.

  other info that might help us debug this:
   Possible interrupt unsafe locking scenario:

	 CPU0                    CPU1
	 ----                    ----
    lock(tasklist_lock);
				 local_irq_disable();
				 lock(css_set_lock);
				 lock(tasklist_lock);
    <Interrupt>
      lock(css_set_lock);

   *** DEADLOCK ***

The condition is highly unlikely to actually happen especially given
that the path is executed only once per boot.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Boqun Feng <boqun.feng@gmail.com>

Variants of proc_create{,_data} that directly take a seq_file show
callback and drastically reduces the boilerplate code in the callers.

All trivial callers converted over.

Signed-off-by: Christoph Hellwig <hch@lst.de>

This patch adds cgroup_subsys->css_rstat_flush().  If a subsystem has
this callback, its csses are linked on cgrp->css_rstat_list and rstat
will call the function whenever the associated cgroup is flushed.
Flush is also performed when such csses are released so that residual
counts aren't lost.

Combined with the rstat API previous patches factored out, this allows
controllers to plug into rstat to manage their statistics in a
scalable way.

Signed-off-by: Tejun Heo <tj@kernel.org>

Base resource stat accounts universial (not specific to any
controller) resource consumptions on top of rstat.  Currently, its
implementation is intermixed with rstat implementation making the code
confusing to follow.

This patch clarifies the distintion by doing the followings.

* Encapsulate base resource stat counters, currently only cputime, in
  struct cgroup_base_stat.

* Move prev_cputime into struct cgroup and initialize it with cgroup.

* Rename the related functions so that they start with cgroup_base_stat.

* Prefix the related variables and field names with b.

This patch doesn't make any functional changes.

Signed-off-by: Tejun Heo <tj@kernel.org>

stat is too generic a name and ends up causing subtle confusions.
It'll be made generic so that controllers can plug into it, which will
make the problem worse.  Let's rename it to something more specific -
cgroup_rstat for cgroup recursive stat.

This patch does the following renames.  No other changes.

* cpu_stat	-> rstat_cpu
* stat		-> rstat
* ?cstat	-> ?rstatc

Note that the renames are selective.  The unrenamed are the ones which
implement basic resource statistics on top of rstat.  This will be
further cleaned up in the following patches.

Signed-off-by: Tejun Heo <tj@kernel.org>

".events" files generate file modified event to notify userland of
possible new events.  Some of the events can be quite bursty
(e.g. memory high event) and generating notification each time is
costly and pointless.

This patch implements a event rate limit mechanism.  If a new
notification is requested before 10ms has passed since the previous
notification, the new notification is delayed till then.

As this only delays from the second notification on in a given close
cluster of notifications, userland reactions to notifications
shouldn't be delayed at all in most cases while avoiding notification
storms.

Signed-off-by: Tejun Heo <tj@kernel.org>

The "cgroup." core interface files bypass the usual interface removal
path and get removed recursively along with the cgroup itself.  While
this works now, the subtle discrepancy gets in the way of implementing
common mechanisms.

This patch updates cgroup core interface file handling so that it's
consistent with controller interface files.  When added, the css is
marked CSS_VISIBLE and they're explicitly removed before the cgroup is
destroyed.

This doesn't cause user-visible behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>