Johannes Weiner 8627c7750a mm: memcontrol: fix cgroup creation failure after many small jobs ... commit 73f576c04b upstream. The memory controller has quite a bit of state that usually outlives the cgroup and pins its CSS until said state disappears. At the same time it imposes a 16-bit limit on the CSS ID space to economically store IDs in the wild. Consequently, when we use cgroups to contain frequent but small and short-lived jobs that leave behind some page cache, we quickly run into the 64k limitations of outstanding CSSs. Creating a new cgroup fails with -ENOSPC while there are only a few, or even no user-visible cgroups in existence. Although pinning CSSs past cgroup removal is common, there are only two instances that actually need an ID after a cgroup is deleted: cache shadow entries and swapout records. Cache shadow entries reference the ID weakly and can deal with the CSS having disappeared when it's looked up later. They pose no hurdle. Swap-out records do need to pin the css to hierarchically attribute swapins after the cgroup has been deleted; though the only pages that remain swapped out after offlining are tmpfs/shmem pages. And those references are under the user's control, so they are manageable. This patch introduces a private 16-bit memcg ID and switches swap and cache shadow entries over to using that. This ID can then be recycled after offlining when the CSS remains pinned only by objects that don't specifically need it. This script demonstrates the problem by faulting one cache page in a new cgroup and deleting it again: set -e mkdir -p pages for x in `seq 128000`; do [ $((x % 1000)) -eq 0 ] && echo $x mkdir /cgroup/foo echo $$ >/cgroup/foo/cgroup.procs echo trex >pages/$x echo $$ >/cgroup/cgroup.procs rmdir /cgroup/foo done When run on an unpatched kernel, we eventually run out of possible IDs even though there are no visible cgroups: [root@ham ~]# ./cssidstress.sh [...] 65000 mkdir: cannot create directory '/cgroup/foo': No space left on device After this patch, the IDs get released upon cgroup destruction and the cache and css objects get released once memory reclaim kicks in. [hannes@cmpxchg.org: init the IDR] Link: http://lkml.kernel.org/r/20160621154601.GA22431@cmpxchg.org Fixes: b2052564e6 ("mm: memcontrol: continue cache reclaim from offlined groups") Link: http://lkml.kernel.org/r/20160617162516.GD19084@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: John Garcia <john.garcia@mesosphere.io> Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Nikolay Borisov <kernel@kyup.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2016-08-16 09:30:51 +02:00
..
acpi
asm-generic	vmlinux.lds: account for destructor sections	2016-08-10 11:49:25 +02:00
clocksource
crypto	crypto: af_alg - Allow af_af_alg_release_parent to be called on nokey path	2016-02-17 12:31:03 -08:00
drm	drm/ttm: Make ttm_bo_mem_compat available	2016-07-27 09:47:35 -07:00
dt-bindings	ARM: DT updates for v4.4	2015-11-10 15:06:26 -08:00
keys
kvm	KVM: arm/arm64: arch_timer: Preserve physical dist. active state on LR.active	2015-11-24 18:07:40 +01:00
linux	mm: memcontrol: fix cgroup creation failure after many small jobs	2016-08-16 09:30:51 +02:00
math-emu
media	videobuf2-core: Check user space planes array in dqbuf	2016-05-04 14:48:50 -07:00
memory
misc
net	vxlan, gre, geneve: Set a large MTU on ovs-created tunnel devices	2016-06-24 10:18:18 -07:00
pcmcia
ras
rdma	IB/security: Restrict use of the write() interface	2016-05-04 14:48:48 -07:00
rxrpc
scsi	scsi: Add intermediate STARGET_REMOVE state to scsi_target_state	2016-06-01 12:15:54 -07:00
soc	ARM: SoC driver updates for v4.4	2015-11-10 15:00:03 -08:00
sound	ALSA: rawmidi: Make snd_rawmidi_transmit() race-free	2016-02-17 12:30:58 -08:00
target	target: Fix WRITE_SAME/DISCARD conversion to linux 512b sectors	2016-03-09 15:34:51 -08:00
trace	Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux	2015-11-11 09:03:01 -08:00
uapi	uapi glibc compat: fix compilation when !__USE_MISC in glibc	2016-06-24 10:18:17 -07:00
video	drm/imx: Match imx-ipuv3-crtc components using device node in platform data	2016-06-07 18:14:37 -07:00
xen	xen: Fix page <-> pfn conversion on 32 bit systems	2016-05-11 11:21:14 +02:00
Kbuild