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 <akpm@linux-foundation.org>: (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
...
Before the previous patch ("memcg: unify slab and other kmem pages
charging"), __mem_cgroup_from_kmem had to handle two types of kmem - slab
pages and pages allocated with alloc_kmem_pages - memcg in the page
struct. Now we can unify it. Since after it, this function becomes tiny
we can fold it into mem_cgroup_from_kmem.
[hughd@google.com: move mem_cgroup_from_kmem into list_lru.c]
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have memcg_kmem_charge and memcg_kmem_uncharge methods for charging and
uncharging kmem pages to memcg, but currently they are not used for
charging slab pages (i.e. they are only used for charging pages allocated
with alloc_kmem_pages). The only reason why the slab subsystem uses
special helpers, memcg_charge_slab and memcg_uncharge_slab, is that it
needs to charge to the memcg of kmem cache while memcg_charge_kmem charges
to the memcg that the current task belongs to.
To remove this diversity, this patch adds an extra argument to
__memcg_kmem_charge that can be a pointer to a memcg or NULL. If it is
not NULL, the function tries to charge to the memcg it points to,
otherwise it charge to the current context. Next, it makes the slab
subsystem use this function to charge slab pages.
Since memcg_charge_kmem and memcg_uncharge_kmem helpers are now used only
in __memcg_kmem_charge and __memcg_kmem_uncharge, they are inlined. Since
__memcg_kmem_charge stores a pointer to the memcg in the page struct, we
don't need memcg_uncharge_slab anymore and can use free_kmem_pages.
Besides, one can now detect which memcg a slab page belongs to by reading
/proc/kpagecgroup.
Note, this patch switches slab to charge-after-alloc design. Since this
design is already used for all other memcg charges, it should not make any
difference.
[hannes@cmpxchg.org: better to have an outer function than a magic parameter for the memcg lookup]
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Charging kmem pages proceeds in two steps. First, we try to charge the
allocation size to the memcg the current task belongs to, then we allocate
a page and "commit" the charge storing the pointer to the memcg in the
page struct.
Such a design looks overcomplicated, because there is not much sense in
trying charging the allocation before actually allocating a page: we won't
be able to consume much memory over the limit even if we charge after
doing the actual allocation, besides we already charge user pages post
factum, so being pedantic with kmem pages just looks pointless.
So this patch simplifies the design by merging the "charge" and the
"commit" steps into the same function, which takes the allocated page.
Also, rename the charge and uncharge methods to memcg_kmem_charge and
memcg_kmem_uncharge and make the charge method return error code instead
of bool to conform to mem_cgroup_try_charge.
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make mem_cgroup_inactive_anon_is_low return bool due to this particular
function only using either one or zero as its return value.
No functional change.
Signed-off-by: Yaowei Bai <bywxiaobai@163.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__memcg_kmem_bypass() decides whether a kmem allocation should be bypassed
to the root memcg. Some conditions that it tests are valid criteria
regarding who should be held accountable; however, there are a couple
unnecessary tests for cold paths - __GFP_FAIL and fatal_signal_pending().
The previous patch updated try_charge() to handle both __GFP_FAIL and
dying tasks correctly and the only thing these two tests are doing is
making accounting less accurate and sprinkling tests for cold path
conditions in the hot paths. There's nothing meaningful gained by these
extra tests.
This patch removes the two unnecessary tests from __memcg_kmem_bypass().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memcg_kmem_newpage_charge() and memcg_kmem_get_cache() are testing the
same series of conditions to decide whether to bypass kmem accounting.
Collect the tests into __memcg_kmem_bypass().
This is pure refactoring.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, try_charge() tries to reclaim memory synchronously when the
high limit is breached; however, if the allocation doesn't have
__GFP_WAIT, synchronous reclaim is skipped. If a process performs only
speculative allocations, it can blow way past the high limit. This is
actually easily reproducible by simply doing "find /". slab/slub
allocator tries speculative allocations first, so as long as there's
memory which can be consumed without blocking, it can keep allocating
memory regardless of the high limit.
This patch makes try_charge() always punt the over-high reclaim to the
return-to-userland path. If try_charge() detects that high limit is
breached, it adds the overage to current->memcg_nr_pages_over_high and
schedules execution of mem_cgroup_handle_over_high() which performs
synchronous reclaim from the return-to-userland path.
As long as kernel doesn't have a run-away allocation spree, this should
provide enough protection while making kmemcg behave more consistently.
It also has the following benefits.
- All over-high reclaims can use GFP_KERNEL regardless of the specific
gfp mask in use, e.g. GFP_NOFS, when the limit was breached.
- It copes with prio inversion. Previously, a low-prio task with
small memory.high might perform over-high reclaim with a bunch of
locks held. If a higher prio task needed any of these locks, it
would have to wait until the low prio task finished reclaim and
released the locks. By handing over-high reclaim to the task exit
path this issue can be avoided.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@kernel.org>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
task_struct->memcg_oom is a sub-struct containing fields which are used
for async memcg oom handling. Most task_struct fields aren't packaged
this way and it can lead to unnecessary alignment paddings. This patch
flattens it.
* task.memcg_oom.memcg -> task.memcg_in_oom
* task.memcg_oom.gfp_mask -> task.memcg_oom_gfp_mask
* task.memcg_oom.order -> task.memcg_oom_order
* task.memcg_oom.may_oom -> task.memcg_may_oom
In addition, task.memcg_may_oom is relocated to where other bitfields are
which reduces the size of task_struct.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull cgroup updates from Tejun Heo:
"The cgroup core saw several significant updates this cycle:
- percpu_rwsem for threadgroup locking is reinstated. This was
temporarily dropped due to down_write latency issues. Oleg's
rework of percpu_rwsem which is scheduled to be merged in this
merge window resolves the issue.
- On the v2 hierarchy, when controllers are enabled and disabled, all
operations are atomic and can fail and revert cleanly. This allows
->can_attach() failure which is necessary for cpu RT slices.
- Tasks now stay associated with the original cgroups after exit
until released. This allows tracking resources held by zombies
(e.g. pids) and makes it easy to find out where zombies came from
on the v2 hierarchy. The pids controller was broken before these
changes as zombies escaped the limits; unfortunately, updating this
behavior required too many invasive changes and I don't think it's
a good idea to backport them, so the pids controller on 4.3, the
first version which included the pids controller, will stay broken
at least until I'm sure about the cgroup core changes.
- Optimization of a couple common tests using static_key"
* 'for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (38 commits)
cgroup: fix race condition around termination check in css_task_iter_next()
blkcg: don't create "io.stat" on the root cgroup
cgroup: drop cgroup__DEVEL__legacy_files_on_dfl
cgroup: replace error handling in cgroup_init() with WARN_ON()s
cgroup: add cgroup_subsys->free() method and use it to fix pids controller
cgroup: keep zombies associated with their original cgroups
cgroup: make css_set_rwsem a spinlock and rename it to css_set_lock
cgroup: don't hold css_set_rwsem across css task iteration
cgroup: reorganize css_task_iter functions
cgroup: factor out css_set_move_task()
cgroup: keep css_set and task lists in chronological order
cgroup: make cgroup_destroy_locked() test cgroup_is_populated()
cgroup: make css_sets pin the associated cgroups
cgroup: relocate cgroup_[try]get/put()
cgroup: move check_for_release() invocation
cgroup: replace cgroup_has_tasks() with cgroup_is_populated()
cgroup: make cgroup->nr_populated count the number of populated css_sets
cgroup: remove an unused parameter from cgroup_task_migrate()
cgroup: fix too early usage of static_branch_disable()
cgroup: make cgroup_update_dfl_csses() migrate all target processes atomically
...
For memcg domains, the amount of available memory was calculated as
min(the amount currently in use + headroom according to memcg,
total clean memory)
This isn't quite correct as what should be capped by the amount of
clean memory is the headroom, not the sum of memory in use and
headroom. For example, if a memcg domain has a significant amount of
dirty memory, the above can lead to a value which is lower than the
current amount in use which doesn't make much sense. In most
circumstances, the above leads to a number which is somewhat but not
drastically lower.
As the amount of memory which can be readily allocated to the memcg
domain is capped by the amount of system-wide clean memory which is
not already assigned to the memcg itself, the number we want is
the amount currently in use +
min(headroom according to memcg, clean memory elsewhere in the system)
This patch updates mem_cgroup_wb_stats() to return the number of
filepages and headroom instead of the calculated available pages.
mdtc_cap_avail() is renamed to mdtc_calc_avail() and performs the
above calculation from file, headroom, dirty and globally clean pages.
v2: Dummy mem_cgroup_wb_stats() implementation wasn't updated leading
to build failure when !CGROUP_WRITEBACK. Fixed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: c2aa723a60 ("writeback: implement memcg writeback domain based throttling")
Signed-off-by: Jens Axboe <axboe@fb.com>
Commit 733a572e66 ("memcg: make mem_cgroup_read_{stat|event}() iterate
possible cpus instead of online") removed the last use of the per memcg
pcp_counter_lock but forgot to remove the variable.
Kill the vestigial variable.
Signed-off-by: Greg Thelen <gthelen@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cgroup core only recently grew generic notification support. Wire up
"memory.events" so that it triggers a file modified event whenever its
content changes.
v2: Refreshed on top of mem_cgroup relocation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Li Zefan <lizefan@huawei.com>
Replace cgroup_subsys->disabled tests in controllers with
cgroup_subsys_enabled(). cgroup_subsys_enabled() requires literal
subsys name as its parameter and thus can't be used for cgroup core
which iterates through controllers. For cgroup core, introduce and
use cgroup_ssid_enabled() which uses slower static_key_enabled() test
and can be indexed by subsys ID.
This leaves cgroup_subsys->disabled unused. Removed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Zefan Li <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
This patchset introduces a new user API for tracking user memory pages
that have not been used for a given period of time. The purpose of this
is to provide the userspace with the means of tracking a workload's
working set, i.e. the set of pages that are actively used by the
workload. Knowing the working set size can be useful for partitioning the
system more efficiently, e.g. by tuning memory cgroup limits
appropriately, or for job placement within a compute cluster.
==== USE CASES ====
The unified cgroup hierarchy has memory.low and memory.high knobs, which
are defined as the low and high boundaries for the workload working set
size. However, the working set size of a workload may be unknown or
change in time. With this patch set, one can periodically estimate the
amount of memory unused by each cgroup and tune their memory.low and
memory.high parameters accordingly, therefore optimizing the overall
memory utilization.
Another use case is balancing workloads within a compute cluster. Knowing
how much memory is not really used by a workload unit may help take a more
optimal decision when considering migrating the unit to another node
within the cluster.
Also, as noted by Minchan, this would be useful for per-process reclaim
(https://lwn.net/Articles/545668/). With idle tracking, we could reclaim idle
pages only by smart user memory manager.
==== USER API ====
The user API consists of two new files:
* /sys/kernel/mm/page_idle/bitmap. This file implements a bitmap where each
bit corresponds to a page, indexed by PFN. When the bit is set, the
corresponding page is idle. A page is considered idle if it has not been
accessed since it was marked idle. To mark a page idle one should set the
bit corresponding to the page by writing to the file. A value written to the
file is OR-ed with the current bitmap value. Only user memory pages can be
marked idle, for other page types input is silently ignored. Writing to this
file beyond max PFN results in the ENXIO error. Only available when
CONFIG_IDLE_PAGE_TRACKING is set.
This file can be used to estimate the amount of pages that are not
used by a particular workload as follows:
1. mark all pages of interest idle by setting corresponding bits in the
/sys/kernel/mm/page_idle/bitmap
2. wait until the workload accesses its working set
3. read /sys/kernel/mm/page_idle/bitmap and count the number of bits set
* /proc/kpagecgroup. This file contains a 64-bit inode number of the
memory cgroup each page is charged to, indexed by PFN. Only available when
CONFIG_MEMCG is set.
This file can be used to find all pages (including unmapped file pages)
accounted to a particular cgroup. Using /sys/kernel/mm/page_idle/bitmap, one
can then estimate the cgroup working set size.
For an example of using these files for estimating the amount of unused
memory pages per each memory cgroup, please see the script attached
below.
==== REASONING ====
The reason to introduce the new user API instead of using
/proc/PID/{clear_refs,smaps} is that the latter has two serious
drawbacks:
- it does not count unmapped file pages
- it affects the reclaimer logic
The new API attempts to overcome them both. For more details on how it
is achieved, please see the comment to patch 6.
==== PATCHSET STRUCTURE ====
The patch set is organized as follows:
- patch 1 adds page_cgroup_ino() helper for the sake of
/proc/kpagecgroup and patches 2-3 do related cleanup
- patch 4 adds /proc/kpagecgroup, which reports cgroup ino each page is
charged to
- patch 5 introduces a new mmu notifier callback, clear_young, which is
a lightweight version of clear_flush_young; it is used in patch 6
- patch 6 implements the idle page tracking feature, including the
userspace API, /sys/kernel/mm/page_idle/bitmap
- patch 7 exports idle flag via /proc/kpageflags
==== SIMILAR WORKS ====
Originally, the patch for tracking idle memory was proposed back in 2011
by Michel Lespinasse (see http://lwn.net/Articles/459269/). The main
difference between Michel's patch and this one is that Michel implemented
a kernel space daemon for estimating idle memory size per cgroup while
this patch only provides the userspace with the minimal API for doing the
job, leaving the rest up to the userspace. However, they both share the
same idea of Idle/Young page flags to avoid affecting the reclaimer logic.
==== PERFORMANCE EVALUATION ====
SPECjvm2008 (https://www.spec.org/jvm2008/) was used to evaluate the
performance impact introduced by this patch set. Three runs were carried
out:
- base: kernel without the patch
- patched: patched kernel, the feature is not used
- patched-active: patched kernel, 1 minute-period daemon is used for
tracking idle memory
For tracking idle memory, idlememstat utility was used:
https://github.com/locker/idlememstat
testcase base patched patched-active
compiler 537.40 ( 0.00)% 532.26 (-0.96)% 538.31 ( 0.17)%
compress 305.47 ( 0.00)% 301.08 (-1.44)% 300.71 (-1.56)%
crypto 284.32 ( 0.00)% 282.21 (-0.74)% 284.87 ( 0.19)%
derby 411.05 ( 0.00)% 413.44 ( 0.58)% 412.07 ( 0.25)%
mpegaudio 189.96 ( 0.00)% 190.87 ( 0.48)% 189.42 (-0.28)%
scimark.large 46.85 ( 0.00)% 46.41 (-0.94)% 47.83 ( 2.09)%
scimark.small 412.91 ( 0.00)% 415.41 ( 0.61)% 421.17 ( 2.00)%
serial 204.23 ( 0.00)% 213.46 ( 4.52)% 203.17 (-0.52)%
startup 36.76 ( 0.00)% 35.49 (-3.45)% 35.64 (-3.05)%
sunflow 115.34 ( 0.00)% 115.08 (-0.23)% 117.37 ( 1.76)%
xml 620.55 ( 0.00)% 619.95 (-0.10)% 620.39 (-0.03)%
composite 211.50 ( 0.00)% 211.15 (-0.17)% 211.67 ( 0.08)%
time idlememstat:
17.20user 65.16system 2:15:23elapsed 1%CPU (0avgtext+0avgdata 8476maxresident)k
448inputs+40outputs (1major+36052minor)pagefaults 0swaps
==== SCRIPT FOR COUNTING IDLE PAGES PER CGROUP ====
#! /usr/bin/python
#
import os
import stat
import errno
import struct
CGROUP_MOUNT = "/sys/fs/cgroup/memory"
BUFSIZE = 8 * 1024 # must be multiple of 8
def get_hugepage_size():
with open("/proc/meminfo", "r") as f:
for s in f:
k, v = s.split(":")
if k == "Hugepagesize":
return int(v.split()[0]) * 1024
PAGE_SIZE = os.sysconf("SC_PAGE_SIZE")
HUGEPAGE_SIZE = get_hugepage_size()
def set_idle():
f = open("/sys/kernel/mm/page_idle/bitmap", "wb", BUFSIZE)
while True:
try:
f.write(struct.pack("Q", pow(2, 64) - 1))
except IOError as err:
if err.errno == errno.ENXIO:
break
raise
f.close()
def count_idle():
f_flags = open("/proc/kpageflags", "rb", BUFSIZE)
f_cgroup = open("/proc/kpagecgroup", "rb", BUFSIZE)
with open("/sys/kernel/mm/page_idle/bitmap", "rb", BUFSIZE) as f:
while f.read(BUFSIZE): pass # update idle flag
idlememsz = {}
while True:
s1, s2 = f_flags.read(8), f_cgroup.read(8)
if not s1 or not s2:
break
flags, = struct.unpack('Q', s1)
cgino, = struct.unpack('Q', s2)
unevictable = (flags >> 18) & 1
huge = (flags >> 22) & 1
idle = (flags >> 25) & 1
if idle and not unevictable:
idlememsz[cgino] = idlememsz.get(cgino, 0) + \
(HUGEPAGE_SIZE if huge else PAGE_SIZE)
f_flags.close()
f_cgroup.close()
return idlememsz
if __name__ == "__main__":
print "Setting the idle flag for each page..."
set_idle()
raw_input("Wait until the workload accesses its working set, "
"then press Enter")
print "Counting idle pages..."
idlememsz = count_idle()
for dir, subdirs, files in os.walk(CGROUP_MOUNT):
ino = os.stat(dir)[stat.ST_INO]
print dir + ": " + str(idlememsz.get(ino, 0) / 1024) + " kB"
==== END SCRIPT ====
This patch (of 8):
Add page_cgroup_ino() helper to memcg.
This function returns the inode number of the closest online ancestor of
the memory cgroup a page is charged to. It is required for exporting
information about which page is charged to which cgroup to userspace,
which will be introduced by a following patch.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The only user is cgwb_bdi_init and that one depends on
CONFIG_CGROUP_WRITEBACK which in turn depends on CONFIG_MEMCG so it
doesn't make much sense to definte an empty stub for !CONFIG_MEMCG.
Moreover ERR_PTR(-EINVAL) is ugly and would lead to runtime crashes if
used in unguarded code paths. Better fail during compilation.
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mem_cgroup structure is defined in mm/memcontrol.c currently which means
that the code outside of this file has to use external API even for
trivial access stuff.
This patch exports mm_struct with its dependencies and makes some of the
exported functions inlines. This even helps to reduce the code size a bit
(make defconfig + CONFIG_MEMCG=y)
text data bss dec hex filename
12355346 1823792 1089536 15268674 e8fb42 vmlinux.before
12354970 1823792 1089536 15268298 e8f9ca vmlinux.after
This is not much (370B) but better than nothing.
We also save a function call in some hot paths like callers of
mem_cgroup_count_vm_event which is used for accounting.
The patch doesn't introduce any functional changes.
[vdavykov@parallels.com: inline memcg_kmem_is_active]
[vdavykov@parallels.com: do not expose type outside of CONFIG_MEMCG]
[akpm@linux-foundation.org: memcontrol.h needs eventfd.h for eventfd_ctx]
[akpm@linux-foundation.org: export mem_cgroup_from_task() to modules]
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull cgroup writeback support from Jens Axboe:
"This is the big pull request for adding cgroup writeback support.
This code has been in development for a long time, and it has been
simmering in for-next for a good chunk of this cycle too. This is one
of those problems that has been talked about for at least half a
decade, finally there's a solution and code to go with it.
Also see last weeks writeup on LWN:
http://lwn.net/Articles/648292/"
* 'for-4.2/writeback' of git://git.kernel.dk/linux-block: (85 commits)
writeback, blkio: add documentation for cgroup writeback support
vfs, writeback: replace FS_CGROUP_WRITEBACK with SB_I_CGROUPWB
writeback: do foreign inode detection iff cgroup writeback is enabled
v9fs: fix error handling in v9fs_session_init()
bdi: fix wrong error return value in cgwb_create()
buffer: remove unusued 'ret' variable
writeback: disassociate inodes from dying bdi_writebacks
writeback: implement foreign cgroup inode bdi_writeback switching
writeback: add lockdep annotation to inode_to_wb()
writeback: use unlocked_inode_to_wb transaction in inode_congested()
writeback: implement unlocked_inode_to_wb transaction and use it for stat updates
writeback: implement [locked_]inode_to_wb_and_lock_list()
writeback: implement foreign cgroup inode detection
writeback: make writeback_control track the inode being written back
writeback: relocate wb[_try]_get(), wb_put(), inode_{attach|detach}_wb()
mm: vmscan: disable memcg direct reclaim stalling if cgroup writeback support is in use
writeback: implement memcg writeback domain based throttling
writeback: reset wb_domain->dirty_limit[_tstmp] when memcg domain size changes
writeback: implement memcg wb_domain
writeback: update wb_over_bg_thresh() to use wb_domain aware operations
...
While cgroup writeback support now connects memcg and blkcg so that
writeback IOs are properly attributed and controlled, the IO back
pressure propagation mechanism implemented in balance_dirty_pages()
and its subroutines wasn't aware of cgroup writeback.
Processes belonging to a memcg may have access to only subset of total
memory available in the system and not factoring this into dirty
throttling rendered it completely ineffective for processes under
memcg limits and memcg ended up building a separate ad-hoc degenerate
mechanism directly into vmscan code to limit page dirtying.
The previous patches updated balance_dirty_pages() and its subroutines
so that they can deal with multiple wb_domain's (writeback domains)
and defined per-memcg wb_domain. Processes belonging to a non-root
memcg are bound to two wb_domains, global wb_domain and memcg
wb_domain, and should be throttled according to IO pressures from both
domains. This patch updates dirty throttling code so that it repeats
similar calculations for the two domains - the differences between the
two are few and minor - and applies the lower of the two sets of
resulting constraints.
wb_over_bg_thresh(), which controls when background writeback
terminates, is also updated to consider both global and memcg
wb_domains. It returns true if dirty is over bg_thresh for either
domain.
This makes the dirty throttling mechanism operational for memcg
domains including writeback-bandwidth-proportional dirty page
distribution inside them but the ad-hoc memcg throttling mechanism in
vmscan is still in place. The next patch will rip it out.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Dirtyable memory is distributed to a wb (bdi_writeback) according to
the relative bandwidth the wb is writing out in the whole system.
This distribution is global - each wb is measured against all other
wb's and gets the proportinately sized portion of the memory in the
whole system.
For cgroup writeback, the amount of dirtyable memory is scoped by
memcg and thus each wb would need to be measured and controlled in its
memcg. IOW, a wb will belong to two writeback domains - the global
and memcg domains.
The previous patches laid the groundwork to support the two wb_domains
and this patch implements memcg wb_domain. memcg->cgwb_domain is
initialized on css online and destroyed on css release,
wb->memcg_completions is added, and __wb_writeout_inc() is updated to
increment completions against both global and memcg wb_domains.
The following patches will update balance_dirty_pages() and its
subroutines to actually consider memcg wb_domain for throttling.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
For the planned cgroup writeback support, on each bdi
(backing_dev_info), each memcg will be served by a separate wb
(bdi_writeback). This patch updates bdi so that a bdi can host
multiple wbs (bdi_writebacks).
On the default hierarchy, blkcg implicitly enables memcg. This allows
using memcg's page ownership for attributing writeback IOs, and every
memcg - blkcg combination can be served by its own wb by assigning a
dedicated wb to each memcg. This means that there may be multiple
wb's of a bdi mapped to the same blkcg. As congested state is per
blkcg - bdi combination, those wb's should share the same congested
state. This is achieved by tracking congested state via
bdi_writeback_congested structs which are keyed by blkcg.
bdi->wb remains unchanged and will keep serving the root cgroup.
cgwb's (cgroup wb's) for non-root cgroups are created on-demand or
looked up while dirtying an inode according to the memcg of the page
being dirtied or current task. Each cgwb is indexed on bdi->cgwb_tree
by its memcg id. Once an inode is associated with its wb, it can be
retrieved using inode_to_wb().
Currently, none of the filesystems has FS_CGROUP_WRITEBACK and all
pages will keep being associated with bdi->wb.
v3: inode_attach_wb() in account_page_dirtied() moved inside
mapping_cap_account_dirty() block where it's known to be !NULL.
Also, an unnecessary NULL check before kfree() removed. Both
detected by the kbuild bot.
v2: Updated so that wb association is per inode and wb is per memcg
rather than blkcg.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: kbuild test robot <fengguang.wu@intel.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Implement mem_cgroup_css_from_page() which returns the
cgroup_subsys_state of the memcg associated with a given page on the
default hierarchy. This will be used by cgroup writeback support.
This function assumes that page->mem_cgroup association doesn't change
until the page is released, which is true on the default hierarchy as
long as replace_page_cache_page() is not used. As the only user of
replace_page_cache_page() is FUSE which won't support cgroup writeback
for the time being, this works for now, and replace_page_cache_page()
will soon be updated so that the invariant actually holds.
Note that the RCU protected page->mem_cgroup access is consistent with
other usages across memcg but ultimately incorrect. These unlocked
accesses are missing required barriers. page->mem_cgroup should be
made an RCU pointer and updated and accessed using RCU operations.
v4: Instead of triggering WARN, return the root css on the traditional
hierarchies. This makes the function a lot easier to deal with
especially as there's no light way to synchronize against
hierarchy rebinding.
v3: s/mem_cgroup_migrate()/mem_cgroup_css_from_page()/
v2: Trigger WARN if the function is used on the traditional
hierarchies and add comment about the assumed invariant.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Linus Torvalds
Hugh Dickins
Vladimir Davydov
Yaowei Bai
Tejun Heo
Greg Thelen
Vladimir Davydov
Michal Hocko