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@xxxxxxxxxxxxxx/ 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 > >
