On 5/30/22 03:49, Muchun Song wrote:
This version is rebased on v5.18.
Since the following patchsets applied. All the kernel memory are charged
with the new APIs of obj_cgroup.
[v17,00/19] The new cgroup slab memory controller [1]
[v5,0/7] Use obj_cgroup APIs to charge kmem pages [2]
But user memory allocations (LRU pages) pinning memcgs for a long time -
it exists at a larger scale and is causing recurring problems in the real
world: page cache doesn't get reclaimed for a long time, or is used by the
second, third, fourth, ... instance of the same job that was restarted into
a new cgroup every time. Unreclaimable dying cgroups pile up, waste memory,
and make page reclaim very inefficient.
We can convert LRU pages and most other raw memcg pins to the objcg direction
to fix this problem, and then the LRU pages will not pin the memcgs.
This patchset aims to make the LRU pages to drop the reference to memory
cgroup by using the APIs of obj_cgroup. Finally, we can see that the number
of the dying cgroups will not increase if we run the following test script.
```bash
#!/bin/bash
dd if=/dev/zero of=temp bs=4096 count=1
cat /proc/cgroups | grep memory
for i in {0..2000}
do
mkdir /sys/fs/cgroup/memory/test$i
echo $$ > /sys/fs/cgroup/memory/test$i/cgroup.procs
cat temp >> log
echo $$ > /sys/fs/cgroup/memory/cgroup.procs
rmdir /sys/fs/cgroup/memory/test$i
done
cat /proc/cgroups | grep memory
rm -f temp log
```
[1] https://lore.kernel.org/linux-mm/20200623015846.1141975-1-guro@xxxxxx/
[2] https://lore.kernel.org/linux-mm/20210319163821.20704-1-songmuchun@xxxxxxxxxxxxx/
v4: https://lore.kernel.org/all/20220524060551.80037-1-songmuchun@xxxxxxxxxxxxx/
v3: https://lore.kernel.org/all/20220216115132.52602-1-songmuchun@xxxxxxxxxxxxx/
v2: https://lore.kernel.org/all/20210916134748.67712-1-songmuchun@xxxxxxxxxxxxx/
v1: https://lore.kernel.org/all/20210814052519.86679-1-songmuchun@xxxxxxxxxxxxx/
RFC v4: https://lore.kernel.org/all/20210527093336.14895-1-songmuchun@xxxxxxxxxxxxx/
RFC v3: https://lore.kernel.org/all/20210421070059.69361-1-songmuchun@xxxxxxxxxxxxx/
RFC v2: https://lore.kernel.org/all/20210409122959.82264-1-songmuchun@xxxxxxxxxxxxx/
RFC v1: https://lore.kernel.org/all/20210330101531.82752-1-songmuchun@xxxxxxxxxxxxx/
v5:
- Lots of improvements from Johannes, Roman and Waiman.
- Fix lockdep warning reported by kernel test robot.
- Add two new patches to do code cleanup.
- Collect Acked-by and Reviewed-by from Johannes and Roman.
- I didn't replace local_irq_disable/enable() to local_lock/unlock_irq() since
local_lock/unlock_irq() takes an parameter, it needs more thinking to transform
it to local_lock. It could be an improvement in the future.
My comment about local_lock/unlock is just a note that
local_irq_disable/enable() have to be eventually replaced. However, we
need to think carefully where to put the newly added local_lock. It is
perfectly fine to keep it as is and leave the conversion as a future
follow-up.
Thank you very much for your work on this patchset.
Cheers,
Longman
