From: Johannes Weiner <hannes@cmpxchg.org>
To: Andrew Morton <akpm@linux-foundation.org>, Jens Axboe <axboe@kernel.dk>
Cc: Dan Schatzberg <schatzberg.dan@gmail.com>,
Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
Michal Hocko <mhocko@kernel.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Hugh Dickins <hughd@google.com>,
Shakeel Butt <shakeelb@google.com>, Roman Gushchin <guro@fb.com>,
Muchun Song <songmuchun@bytedance.com>,
Yang Shi <shy828301@gmail.com>,
Alex Shi <alex.shi@linux.alibaba.com>,
Alexander Duyck <alexander.h.duyck@linux.intel.com>,
Wei Yang <richard.weiyang@gmail.com>,
"open list:BLOCK LAYER" <linux-block@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
"open list:CONTROL GROUP (CGROUP)" <cgroups@vger.kernel.org>,
"open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>
Subject: Re: [PATCH V12 0/3] Charge loop device i/o to issuing cgroup
Date: Mon, 12 Apr 2021 11:45:43 -0400 [thread overview]
Message-ID: <YHRrJ9V6ivpH2QUN@cmpxchg.org> (raw)
In-Reply-To: <20210402191638.3249835-1-schatzberg.dan@gmail.com>
It looks like all feedback has been addressed and there hasn't been
any new activity on it in a while.
As per the suggestion last time [1], Andrew, Jens, could this go
through the -mm tree to deal with the memcg conflicts?
[1] https://lore.kernel.org/lkml/CALvZod6FMQQC17Zsu9xoKs=dFWaJdMC2Qk3YiDPUUQHx8teLYg@mail.gmail.com/
On Fri, Apr 02, 2021 at 12:16:31PM -0700, Dan Schatzberg wrote:
> No major changes, rebased on top of latest mm tree
>
> Changes since V12:
>
> * Small change to get_mem_cgroup_from_mm to avoid needing
> get_active_memcg
>
> Changes since V11:
>
> * Removed WQ_MEM_RECLAIM flag from loop workqueue. Technically, this
> can be driven by writeback, but this was causing a warning in xfs
> and likely other filesystems aren't equipped to be driven by reclaim
> at the VFS layer.
> * Included a small fix from Colin Ian King.
> * reworked get_mem_cgroup_from_mm to institute the necessary charge
> priority.
>
> Changes since V10:
>
> * Added page-cache charging to mm: Charge active memcg when no mm is set
>
> Changes since V9:
>
> * Rebased against linus's branch which now includes Roman Gushchin's
> patch this series is based off of
>
> Changes since V8:
>
> * Rebased on top of Roman Gushchin's patch
> (https://lkml.org/lkml/2020/8/21/1464) which provides the nesting
> support for setting active memcg. Dropped the patch from this series
> that did the same thing.
>
> Changes since V7:
>
> * Rebased against linus's branch
>
> Changes since V6:
>
> * Added separate spinlock for worker synchronization
> * Minor style changes
>
> Changes since V5:
>
> * Fixed a missing css_put when failing to allocate a worker
> * Minor style changes
>
> Changes since V4:
>
> Only patches 1 and 2 have changed.
>
> * Fixed irq lock ordering bug
> * Simplified loop detach
> * Added support for nesting memalloc_use_memcg
>
> Changes since V3:
>
> * Fix race on loop device destruction and deferred worker cleanup
> * Ensure charge on shmem_swapin_page works just like getpage
> * Minor style changes
>
> Changes since V2:
>
> * Deferred destruction of workqueue items so in the common case there
> is no allocation needed
>
> Changes since V1:
>
> * Split out and reordered patches so cgroup charging changes are
> separate from kworker -> workqueue change
>
> * Add mem_css to struct loop_cmd to simplify logic
>
> The loop device runs all i/o to the backing file on a separate kworker
> thread which results in all i/o being charged to the root cgroup. This
> allows a loop device to be used to trivially bypass resource limits
> and other policy. This patch series fixes this gap in accounting.
>
> A simple script to demonstrate this behavior on cgroupv2 machine:
>
> '''
> #!/bin/bash
> set -e
>
> CGROUP=/sys/fs/cgroup/test.slice
> LOOP_DEV=/dev/loop0
>
> if [[ ! -d $CGROUP ]]
> then
> sudo mkdir $CGROUP
> fi
>
> grep oom_kill $CGROUP/memory.events
>
> # Set a memory limit, write more than that limit to tmpfs -> OOM kill
> sudo unshare -m bash -c "
> echo \$\$ > $CGROUP/cgroup.procs;
> echo 0 > $CGROUP/memory.swap.max;
> echo 64M > $CGROUP/memory.max;
> mount -t tmpfs -o size=512m tmpfs /tmp;
> dd if=/dev/zero of=/tmp/file bs=1M count=256" || true
>
> grep oom_kill $CGROUP/memory.events
>
> # Set a memory limit, write more than that limit through loopback
> # device -> no OOM kill
> sudo unshare -m bash -c "
> echo \$\$ > $CGROUP/cgroup.procs;
> echo 0 > $CGROUP/memory.swap.max;
> echo 64M > $CGROUP/memory.max;
> mount -t tmpfs -o size=512m tmpfs /tmp;
> truncate -s 512m /tmp/backing_file
> losetup $LOOP_DEV /tmp/backing_file
> dd if=/dev/zero of=$LOOP_DEV bs=1M count=256;
> losetup -D $LOOP_DEV" || true
>
> grep oom_kill $CGROUP/memory.events
> '''
>
> Naively charging cgroups could result in priority inversions through
> the single kworker thread in the case where multiple cgroups are
> reading/writing to the same loop device. This patch series does some
> minor modification to the loop driver so that each cgroup can make
> forward progress independently to avoid this inversion.
>
> With this patch series applied, the above script triggers OOM kills
> when writing through the loop device as expected.
>
> Dan Schatzberg (3):
> loop: Use worker per cgroup instead of kworker
> mm: Charge active memcg when no mm is set
> loop: Charge i/o to mem and blk cg
>
> drivers/block/loop.c | 244 ++++++++++++++++++++++++++++++-------
> drivers/block/loop.h | 15 ++-
> include/linux/memcontrol.h | 6 +
> kernel/cgroup/cgroup.c | 1 +
> mm/filemap.c | 2 +-
> mm/memcontrol.c | 49 +++++---
> mm/shmem.c | 4 +-
> 7 files changed, 253 insertions(+), 68 deletions(-)
>
> --
> 2.30.2
>
>
next prev parent reply other threads:[~2021-04-12 15:45 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-02 19:16 [PATCH V12 0/3] Charge loop device i/o to issuing cgroup Dan Schatzberg
2021-04-02 19:16 ` [PATCH 1/3] loop: Use worker per cgroup instead of kworker Dan Schatzberg
2021-04-06 1:44 ` Ming Lei
2021-04-02 19:16 ` [PATCH 2/3] mm: Charge active memcg when no mm is set Dan Schatzberg
2021-04-03 5:47 ` [External] " Muchun Song
2021-04-02 19:16 ` [PATCH 3/3] loop: Charge i/o to mem and blk cg Dan Schatzberg
2021-04-06 3:23 ` Ming Lei
[not found] ` <20210403020902.1384-1-hdanton@sina.com>
2021-04-06 18:59 ` [PATCH 1/3] loop: Use worker per cgroup instead of kworker Dan Schatzberg
[not found] ` <20210407065300.1478-1-hdanton@sina.com>
2021-04-07 14:43 ` Dan Schatzberg
2021-04-12 15:45 ` Johannes Weiner [this message]
2021-04-12 15:50 ` [PATCH V12 0/3] Charge loop device i/o to issuing cgroup Jens Axboe
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