linux-toradex.git/kernel/cpuset.c, branch v4.6-rc3

Merge branch 'for-4.6-ns' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2016-03-21T17:05:13+00:00

Pull cgroup namespace support from Tejun Heo:
 "These are changes to implement namespace support for cgroup which has
  been pending for quite some time now.  It is very straight-forward and
  only affects what part of cgroup hierarchies are visible.

  After unsharing, mounting a cgroup fs will be scoped to the cgroups
  the task belonged to at the time of unsharing and the cgroup paths
  exposed to userland would be adjusted accordingly"

* 'for-4.6-ns' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: fix and restructure error handling in copy_cgroup_ns()
  cgroup: fix alloc_cgroup_ns() error handling in copy_cgroup_ns()
  Add FS_USERNS_FLAG to cgroup fs
  cgroup: Add documentation for cgroup namespaces
  cgroup: mount cgroupns-root when inside non-init cgroupns
  kernfs: define kernfs_node_dentry
  cgroup: cgroup namespace setns support
  cgroup: introduce cgroup namespaces
  sched: new clone flag CLONE_NEWCGROUP for cgroup namespace
  kernfs: Add API to generate relative kernfs path

cgroup: convert cgroup_subsys flag fields to bool bitfields

2016-02-23T15:00:50+00:00

Signed-off-by: Tejun Heo 
Cc: Li Zefan 
Cc: Ingo Molnar 
Cc: Peter Zijlstra

cgroup: introduce cgroup namespaces

2016-02-16T18:04:58+00:00

Introduce the ability to create new cgroup namespace. The newly created
cgroup namespace remembers the cgroup of the process at the point
of creation of the cgroup namespace (referred as cgroupns-root).
The main purpose of cgroup namespace is to virtualize the contents
of /proc/self/cgroup file. Processes inside a cgroup namespace
are only able to see paths relative to their namespace root
(unless they are moved outside of their cgroupns-root, at which point
 they will see a relative path from their cgroupns-root).
For a correctly setup container this enables container-tools
(like libcontainer, lxc, lmctfy, etc.) to create completely virtualized
containers without leaking system level cgroup hierarchy to the task.
This patch only implements the 'unshare' part of the cgroupns.

Signed-off-by: Aditya Kali 
Signed-off-by: Serge Hallyn 
Signed-off-by: Tejun Heo

cpuset: make mm migration asynchronous

2016-01-22T15:22:46+00:00

If "cpuset.memory_migrate" is set, when a process is moved from one
cpuset to another with a different memory node mask, pages in used by
the process are migrated to the new set of nodes.  This was performed
synchronously in the ->attach() callback, which is synchronized
against process management.  Recently, the synchronization was changed
from per-process rwsem to global percpu rwsem for simplicity and
optimization.

Combined with the synchronous mm migration, this led to deadlocks
because mm migration could schedule a work item which may in turn try
to create a new worker blocking on the process management lock held
from cgroup process migration path.

This heavy an operation shouldn't be performed synchronously from that
deep inside cgroup migration in the first place.  This patch punts the
actual migration to an ordered workqueue and updates cgroup process
migration and cpuset config update paths to flush the workqueue after
all locks are released.  This way, the operations still seem
synchronous to userland without entangling mm migration with process
management synchronization.  CPU hotplug can also invoke mm migration
but there's no reason for it to wait for mm migrations and thus
doesn't synchronize against their completions.

Signed-off-by: Tejun Heo 
Reported-and-tested-by: Christian Borntraeger 
Cc: stable@vger.kernel.org # v4.4+

Merge branch 'for-4.4-fixes' into for-4.5

2015-12-03T15:22:52+00:00

cgroup: fix handling of multi-destination migration from subtree_control enabling

2015-12-03T15:18:21+00:00

Consider the following v2 hierarchy.

  P0 (+memory) --- P1 (-memory) --- A
                                 \- B
       
P0 has memory enabled in its subtree_control while P1 doesn't.  If
both A and B contain processes, they would belong to the memory css of
P1.  Now if memory is enabled on P1's subtree_control, memory csses
should be created on both A and B and A's processes should be moved to
the former and B's processes the latter.  IOW, enabling controllers
can cause atomic migrations into different csses.

The core cgroup migration logic has been updated accordingly but the
controller migration methods haven't and still assume that all tasks
migrate to a single target css; furthermore, the methods were fed the
css in which subtree_control was updated which is the parent of the
target csses.  pids controller depends on the migration methods to
move charges and this made the controller attribute charges to the
wrong csses often triggering the following warning by driving a
counter negative.

 WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40()
 Modules linked in:
 CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29
 ...
  ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000
  ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00
  ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8
 Call Trace:
  [] dump_stack+0x4e/0x82
  [] warn_slowpath_common+0x82/0xc0
  [] warn_slowpath_null+0x1a/0x20
  [] pids_cancel.constprop.6+0x31/0x40
  [] pids_can_attach+0x6d/0xf0
  [] cgroup_taskset_migrate+0x6c/0x330
  [] cgroup_migrate+0xf5/0x190
  [] cgroup_attach_task+0x176/0x200
  [] __cgroup_procs_write+0x2ad/0x460
  [] cgroup_procs_write+0x14/0x20
  [] cgroup_file_write+0x35/0x1c0
  [] kernfs_fop_write+0x141/0x190
  [] __vfs_write+0x28/0xe0
  [] vfs_write+0xac/0x1a0
  [] SyS_write+0x49/0xb0
  [] entry_SYSCALL_64_fastpath+0x12/0x76

This patch fixes the bug by removing @css parameter from the three
migration methods, ->can_attach, ->cancel_attach() and ->attach() and
updating cgroup_taskset iteration helpers also return the destination
css in addition to the task being migrated.  All controllers are
updated accordingly.

* Controllers which don't care whether there are one or multiple
  target csses can be converted trivially.  cpu, io, freezer, perf,
  netclassid and netprio fall in this category.

* cpuset's current implementation assumes that there's single source
  and destination and thus doesn't support v2 hierarchy already.  The
  only change made by this patchset is how that single destination css
  is obtained.

* memory migration path already doesn't do anything on v2.  How the
  single destination css is obtained is updated and the prep stage of
  mem_cgroup_can_attach() is reordered to accomodate the change.

* pids is the only controller which was affected by this bug.  It now
  correctly handles multi-destination migrations and no longer causes
  counter underflow from incorrect accounting.

Signed-off-by: Tejun Heo 
Reported-and-tested-by: Daniel Wagner 
Cc: Aleksa Sarai

cpuset: Replace all instances of time_t with time64_t

2015-11-25T19:00:05+00:00

The following patch replaces all instances of time_t with time64_t i.e.
change the type used for representing time from 32-bit to 64-bit. All
32-bit kernels to date use a signed 32-bit time_t type, which can only
represent time until January 2038. Since embedded systems running 32-bit
Linux are going to survive beyond that date, we have to change all
current uses, in a backwards compatible way.

The patch also changes the function get_seconds() that returns a 32-bit
integer to ktime_get_seconds() that returns seconds as 64-bit integer.

The patch changes the type of ticks from time_t to u32. We keep ticks as
32-bits as the function uses 32-bit arithmetic which would prove less
expensive than 64-bit arithmetic and the function is expected to be
called atleast once every 32 seconds.

Signed-off-by: Heena Sirwani 
Reviewed-by: Arnd Bergmann 
Signed-off-by: Arnd Bergmann 
Signed-off-by: Tejun Heo

Merge branch 'akpm' (patches from Andrew)

2015-11-06T07:10:54+00:00

Merge patch-bomb from Andrew Morton:

 - inotify tweaks

 - some ocfs2 updates (many more are awaiting review)

 - various misc bits

 - kernel/watchdog.c updates

 - Some of mm.  I have a huge number of MM patches this time and quite a
   lot of it is quite difficult and much will be held over to next time.

* emailed patches from Andrew Morton : (162 commits)
  selftests: vm: add tests for lock on fault
  mm: mlock: add mlock flags to enable VM_LOCKONFAULT usage
  mm: introduce VM_LOCKONFAULT
  mm: mlock: add new mlock system call
  mm: mlock: refactor mlock, munlock, and munlockall code
  kasan: always taint kernel on report
  mm, slub, kasan: enable user tracking by default with KASAN=y
  kasan: use IS_ALIGNED in memory_is_poisoned_8()
  kasan: Fix a type conversion error
  lib: test_kasan: add some testcases
  kasan: update reference to kasan prototype repo
  kasan: move KASAN_SANITIZE in arch/x86/boot/Makefile
  kasan: various fixes in documentation
  kasan: update log messages
  kasan: accurately determine the type of the bad access
  kasan: update reported bug types for kernel memory accesses
  kasan: update reported bug types for not user nor kernel memory accesses
  mm/kasan: prevent deadlock in kasan reporting
  mm/kasan: don't use kasan shadow pointer in generic functions
  mm/kasan: MODULE_VADDR is not available on all archs
  ...

mm, oom: remove task_lock protecting comm printing

2015-11-06T03:34:48+00:00

The oom killer takes task_lock() in a couple of places solely to protect
printing the task's comm.

A process's comm, including current's comm, may change due to
/proc/pid/comm or PR_SET_NAME.

The comm will always be NULL-terminated, so the worst race scenario would
only be during update.  We can tolerate a comm being printed that is in
the middle of an update to avoid taking the lock.

Other locations in the kernel have already dropped task_lock() when
printing comm, so this is consistent.

Signed-off-by: David Rientjes 
Suggested-by: Oleg Nesterov 
Cc: Michal Hocko 
Cc: Vladimir Davydov 
Cc: Sergey Senozhatsky 
Acked-by: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroup: replace cgroup_has_tasks() with cgroup_is_populated()

2015-10-15T20:41:50+00:00

Currently, cgroup_has_tasks() tests whether the target cgroup has any
css_set linked to it.  This works because a css_set's refcnt converges
with the number of tasks linked to it and thus there's no css_set
linked to a cgroup if it doesn't have any live tasks.

To help tracking resource usage of zombie tasks, putting the ref of
css_set will be separated from disassociating the task from the
css_set which means that a cgroup may have css_sets linked to it even
when it doesn't have any live tasks.

This patch replaces cgroup_has_tasks() with cgroup_is_populated()
which tests cgroup->nr_populated instead which locally counts the
number of populated css_sets.  Unlike cgroup_has_tasks(),
cgroup_is_populated() is recursive - if any of the descendants is
populated, the cgroup is populated too.  While this changes the
meaning of the test, all the existing users are okay with the change.

While at it, replace the open-coded ->populated_cnt test in
cgroup_events_show() with cgroup_is_populated().

Signed-off-by: Tejun Heo 
Cc: Li Zefan 
Cc: Johannes Weiner 
Cc: Michal Hocko