[PATCH v7 00/34] kmemcg shrinkers

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Initial notes:
==============

Please pay attention to new patches that are debuting in this series. Patch1
changes our unused countries for int to long, since Dave noticed that it wasn't
being enough in some cases. Aside from that, the major change is that we now
compute and keep deferred work per-node (Patch13). The biggest effect of this,
is that to avoid storing a new nodemask in the stack, I am passing only the
node id down to the API. This means that the lru API *does not* take a nodemask
any longer, which in turn, makes it simpler.

I deeply considered this matter, and decided this would be the best way to go.
It is not different from what I have already done for memcgs: Only a single one
is passed down, and the complexity of scanning them is moved upwards to the
caller, where all the scanning logic should belong anyway.

If you want, you can also grab from branch "kmemcg-lru-shrinker" at:

	git://git.kernel.org/pub/scm/linux/kernel/git/glommer/memcg.git

I hope the performance problems are all gone. My testing now shows a smoother
and steady state for the objects during the lifetime of the workload, and
postmark numbers are closer to base, although we do deviate a bit.

Main changes from *v6:
* Change nr_unused_dentry to long, Dave reported an int not being enough
* Fixed shrink_list leak, by Dave
* LRU API now gets a node id, instead of a node mask.
* per-node deferred work, leading to smoother behavior

Hi,

This patchset implements targeted shrinking for memcg when kmem limits are
present. So far, we've been accounting kernel objects but failing allocations
when short of memory. This is because our only option would be to call the
global shrinker, depleting objects from all caches and breaking isolation.

The main idea is to associate per-memcg lists with each of the LRUs. The main
LRU still provides a single entry point and when adding or removing an element
from the LRU, we use the page information to figure out which memcg it belongs
to and relay it to the right list.

Base work:
==========

Please note that this builds upon the recent work from Dave Chinner that
sanitizes the LRU shrinking API and make the shrinkers node aware. Node
awareness is not *strictly* needed for my work, but I still perceive it
as an advantage. The API unification is a major need, and I build upon it
heavily. That allows us to manipulate the LRUs without knowledge of the
underlying objects with ease. This time, I am including that work here as
a baseline.

Main changes from *v6:
* Change nr_unused_dentry to long, Dave reported an int not being enough
* Fixed shrink_list leak, by Dave
* LRU API now gets a node id, instead of a node mask.
* per-node deferred work, leading to smoother behavior

Main changes from *v5:
* Rebased to linux-next, and fix the conflicts with the dcache.
* Make sure LRU_RETRY only retry once
* Prevent the bcache shrinker to scan the caches when disabled (by returning
  0 in the count function)
* Fix i915 return code when mutex cannot be acquired.
* Only scan less-than-batch objects in memcg scenarios

Main changes from *v4:
* Fixed a bug in user-generated memcg pressure
* Fixed overly-agressive slab shrinker behavior spotted by Mel Gorman
* Various other fixes and comments by Mel Gorman

Main changes from *v3:
* Merged suggestions from mailing list.
* Removed the memcg-walking code from LRU. vmscan now drives all the hierarchy
  decisions, which makes more sense
* lazily free the old memcg arrays (needs now to be saved in struct lru). Since
  we need to call synchronize_rcu, calling it for every LRU can become expensive
* Moved the dead memcg shrinker to vmpressure. Already independently sent to
  linux-mm for review.
* Changed locking convention for LRU_RETRY. It now needs to return locked, which
  silents warnings about possible lock unbalance (although previous code was
  correct)

Main changes from *v2:
* shrink dead memcgs when global pressure kicks in. Uses the new lru API.
* bugfixes and comments from the mailing list.
* proper hierarchy-aware walk in shrink_slab.

Main changes from *v1:
* merged comments from the mailing list
* reworked lru-memcg API
* effective proportional shrinking
* sanitized locking on the memcg side
* bill user memory first when kmem == umem
* various bugfixes

Dave Chinner (17):
  dcache: convert dentry_stat.nr_unused to per-cpu counters
  dentry: move to per-sb LRU locks
  dcache: remove dentries from LRU before putting on dispose list
  mm: new shrinker API
  shrinker: convert superblock shrinkers to new API
  list: add a new LRU list type
  inode: convert inode lru list to generic lru list code.
  dcache: convert to use new lru list infrastructure
  list_lru: per-node list infrastructure
  shrinker: add node awareness
  fs: convert inode and dentry shrinking to be node aware
  xfs: convert buftarg LRU to generic code
  xfs: convert dquot cache lru to list_lru
  fs: convert fs shrinkers to new scan/count API
  drivers: convert shrinkers to new count/scan API
  shrinker: convert remaining shrinkers to count/scan API
  shrinker: Kill old ->shrink API.

Glauber Costa (17):
  fs: bump inode and dentry counters to long
  super: fix calculation of shrinkable objects for small numbers
  vmscan: per-node deferred work
  list_lru: per-node API
  i915: bail out earlier when shrinker cannot acquire mutex
  hugepage: convert huge zero page shrinker to new shrinker API
  vmscan: also shrink slab in memcg pressure
  memcg,list_lru: duplicate LRUs upon kmemcg creation
  lru: add an element to a memcg list
  list_lru: per-memcg walks
  memcg: per-memcg kmem shrinking
  memcg: scan cache objects hierarchically
  vmscan: take at least one pass with shrinkers
  super: targeted memcg reclaim
  memcg: move initialization to memcg creation
  vmpressure: in-kernel notifications
  memcg: reap dead memcgs upon global memory pressure.

 arch/x86/kvm/mmu.c                        |  28 +-
 drivers/gpu/drm/i915/i915_dma.c           |   4 +-
 drivers/gpu/drm/i915/i915_gem.c           |  71 +++--
 drivers/gpu/drm/ttm/ttm_page_alloc.c      |  48 ++--
 drivers/gpu/drm/ttm/ttm_page_alloc_dma.c  |  55 ++--
 drivers/md/bcache/btree.c                 |  43 +--
 drivers/md/bcache/sysfs.c                 |   2 +-
 drivers/md/dm-bufio.c                     |  65 +++--
 drivers/staging/android/ashmem.c          |  46 +++-
 drivers/staging/android/lowmemorykiller.c |  40 +--
 drivers/staging/zcache/zcache-main.c      |  29 +-
 fs/dcache.c                               | 259 +++++++++++-------
 fs/drop_caches.c                          |   1 +
 fs/ext4/extents_status.c                  |  30 ++-
 fs/gfs2/glock.c                           |  30 ++-
 fs/gfs2/main.c                            |   3 +-
 fs/gfs2/quota.c                           |  14 +-
 fs/gfs2/quota.h                           |   4 +-
 fs/inode.c                                | 194 ++++++--------
 fs/internal.h                             |   7 +-
 fs/mbcache.c                              |  53 ++--
 fs/nfs/dir.c                              |  20 +-
 fs/nfs/internal.h                         |   4 +-
 fs/nfs/super.c                            |   3 +-
 fs/nfsd/nfscache.c                        |  31 ++-
 fs/quota/dquot.c                          |  39 ++-
 fs/super.c                                | 104 +++++---
 fs/ubifs/shrinker.c                       |  20 +-
 fs/ubifs/super.c                          |   3 +-
 fs/ubifs/ubifs.h                          |   3 +-
 fs/xfs/xfs_buf.c                          | 170 ++++++------
 fs/xfs/xfs_buf.h                          |   5 +-
 fs/xfs/xfs_dquot.c                        |   7 +-
 fs/xfs/xfs_icache.c                       |   4 +-
 fs/xfs/xfs_icache.h                       |   2 +-
 fs/xfs/xfs_qm.c                           | 277 +++++++++----------
 fs/xfs/xfs_qm.h                           |   4 +-
 fs/xfs/xfs_super.c                        |  12 +-
 include/linux/dcache.h                    |  14 +-
 include/linux/fs.h                        |  25 +-
 include/linux/list_lru.h                  | 162 +++++++++++
 include/linux/memcontrol.h                |  45 ++++
 include/linux/shrinker.h                  |  72 ++++-
 include/linux/swap.h                      |   2 +
 include/linux/vmpressure.h                |   6 +
 include/trace/events/vmscan.h             |   4 +-
 include/uapi/linux/fs.h                   |   6 +-
 kernel/sysctl.c                           |   6 +-
 lib/Makefile                              |   2 +-
 lib/list_lru.c                            | 396 +++++++++++++++++++++++++++
 mm/huge_memory.c                          |  17 +-
 mm/memcontrol.c                           | 430 ++++++++++++++++++++++++++----
 mm/memory-failure.c                       |   2 +
 mm/slab_common.c                          |   1 -
 mm/vmpressure.c                           |  52 +++-
 mm/vmscan.c                               | 378 +++++++++++++++++++-------
 net/sunrpc/auth.c                         |  45 +++-
 57 files changed, 2438 insertions(+), 961 deletions(-)
 create mode 100644 include/linux/list_lru.h
 create mode 100644 lib/list_lru.c

-- 
1.8.1.4

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