在 2021/12/14 0:53, Muchun Song 写道: > This series is based on Linux 5.16-rc3. > > In our server, we found a suspected memory leak problem. The kmalloc-32 > consumes more than 6GB of memory. Other kmem_caches consume less than 2GB > memory. > > After our in-depth analysis, the memory consumption of kmalloc-32 slab > cache is the cause of list_lru_one allocation. IIUC, you mean: "the memory consumption of kmalloc-32 slab cache is caused by list_lru_one allocation" > > crash> p memcg_nr_cache_ids > memcg_nr_cache_ids = $2 = 24574 > > memcg_nr_cache_ids is very large and memory consumption of each list_lru > can be calculated with the following formula. > > num_numa_node * memcg_nr_cache_ids * 32 (kmalloc-32) > > There are 4 numa nodes in our system, so each list_lru consumes ~3MB. > > crash> list super_blocks | wc -l > 952 > > Every mount will register 2 list lrus, one is for inode, another is for > dentry. There are 952 super_blocks. So the total memory is 952 * 2 * 3 > MB (~5.6GB). But now the number of memory cgroups is less than 500. So I > guess more than 12286 memory cgroups have been created on this machine (I > do not know why there are so many cgroups, it may be a user's bug or > the user really want to do that). Because memcg_nr_cache_ids has not been > reduced to a suitable value. It leads to waste a lot of memory. If we want > to reduce memcg_nr_cache_ids, we have to *reboot* the server. This is not > what we want. > > In order to reduce memcg_nr_cache_ids, I had posted a patchset [1] to do > this. But this did not fundamentally solve the problem. > > We currently allocate scope for every memcg to be able to tracked on every > superblock instantiated in the system, regardless of whether that superblock > is even accessible to that memcg. > > These huge memcg counts come from container hosts where memcgs are confined > to just a small subset of the total number of superblocks that instantiated > at any given point in time. > > For these systems with huge container counts, list_lru does not need the > capability of tracking every memcg on every superblock. > > What it comes down to is that the list_lru is only needed for a given memcg > if that memcg is instatiating and freeing objects on a given list_lru. > > As Dave said, "Which makes me think we should be moving more towards 'add the > memcg to the list_lru at the first insert' model rather than 'instantiate > all at memcg init time just in case'." > > This patchset aims to optimize the list lru memory consumption from different > aspects. > > I had done a easy test to show the optimization. I create 10k memory cgroups > and mount 10k filesystems in the systems. We use free command to show how many > memory does the systems comsumes after this operation (There are 2 numa nodes > in the system). > > +-----------------------+------------------------+ > | condition | memory consumption | > +-----------------------+------------------------+ > | without this patchset | 24464 MB | > +-----------------------+------------------------+ > | after patch 1 | 21957 MB | <--------+ > +-----------------------+------------------------+ | > | after patch 11 | 6895 MB | | > +-----------------------+------------------------+ | > | after patch 13 | 4367 MB | | > +-----------------------+------------------------+ | > | > The more the number of nodes, the more obvious the effect---+ > > BTW, there was a recent discussion [2] on the same issue. > > [1] https://lore.kernel.org/linux-fsdevel/20210428094949.43579-1-songmuchun@xxxxxxxxxxxxx/ > [2] https://lore.kernel.org/linux-fsdevel/20210405054848.GA1077931@xxxxxxxxxx/ > > This series not only optimizes the memory usage of list_lru but also > simplifies the code. > > Changelog in v4: > - Remove some code cleanup patches since they are already merged. > - Collect Acked-by from Theodore. > - Fix ntfs3 (Thanks Argillander). > > Changelog in v3: > - Fix mixing advanced and normal XArray concepts (Thanks to Matthew). > - Split one patch into per-filesystem patches. > > Changelog in v2: > - Update Documentation/filesystems/porting.rst suggested by Dave. > - Add a comment above alloc_inode_sb() suggested by Dave. > - Rework some patch's commit log. > - Add patch 18-21. > > Thanks Dave. > > Muchun Song (17): > mm: list_lru: optimize memory consumption of arrays of per cgroup > lists > mm: introduce kmem_cache_alloc_lru > fs: introduce alloc_inode_sb() to allocate filesystems specific inode > fs: allocate inode by using alloc_inode_sb() > f2fs: allocate inode by using alloc_inode_sb() > nfs42: use a specific kmem_cache to allocate nfs4_xattr_entry > mm: dcache: use kmem_cache_alloc_lru() to allocate dentry > xarray: use kmem_cache_alloc_lru to allocate xa_node > mm: workingset: use xas_set_lru() to pass shadow_nodes > mm: memcontrol: move memcg_online_kmem() to mem_cgroup_css_online() > mm: list_lru: allocate list_lru_one only when needed > mm: list_lru: rename memcg_drain_all_list_lrus to > memcg_reparent_list_lrus > mm: list_lru: replace linear array with xarray > mm: memcontrol: reuse memory cgroup ID for kmem ID > mm: memcontrol: fix cannot alloc the maximum memcg ID > mm: list_lru: rename list_lru_per_memcg to list_lru_memcg > mm: memcontrol: rename memcg_cache_id to memcg_kmem_id > > Documentation/filesystems/porting.rst | 5 + > block/bdev.c | 2 +- > drivers/dax/super.c | 2 +- > fs/9p/vfs_inode.c | 2 +- > fs/adfs/super.c | 2 +- > fs/affs/super.c | 2 +- > fs/afs/super.c | 2 +- > fs/befs/linuxvfs.c | 2 +- > fs/bfs/inode.c | 2 +- > fs/btrfs/inode.c | 2 +- > fs/ceph/inode.c | 2 +- > fs/cifs/cifsfs.c | 2 +- > fs/coda/inode.c | 2 +- > fs/dcache.c | 3 +- > fs/ecryptfs/super.c | 2 +- > fs/efs/super.c | 2 +- > fs/erofs/super.c | 2 +- > fs/exfat/super.c | 2 +- > fs/ext2/super.c | 2 +- > fs/ext4/super.c | 2 +- > fs/f2fs/super.c | 8 +- > fs/fat/inode.c | 2 +- > fs/freevxfs/vxfs_super.c | 2 +- > fs/fuse/inode.c | 2 +- > fs/gfs2/super.c | 2 +- > fs/hfs/super.c | 2 +- > fs/hfsplus/super.c | 2 +- > fs/hostfs/hostfs_kern.c | 2 +- > fs/hpfs/super.c | 2 +- > fs/hugetlbfs/inode.c | 2 +- > fs/inode.c | 2 +- > fs/isofs/inode.c | 2 +- > fs/jffs2/super.c | 2 +- > fs/jfs/super.c | 2 +- > fs/minix/inode.c | 2 +- > fs/nfs/inode.c | 2 +- > fs/nfs/nfs42xattr.c | 95 ++++---- > fs/nilfs2/super.c | 2 +- > fs/ntfs/inode.c | 2 +- > fs/ntfs3/super.c | 2 +- > fs/ocfs2/dlmfs/dlmfs.c | 2 +- > fs/ocfs2/super.c | 2 +- > fs/openpromfs/inode.c | 2 +- > fs/orangefs/super.c | 2 +- > fs/overlayfs/super.c | 2 +- > fs/proc/inode.c | 2 +- > fs/qnx4/inode.c | 2 +- > fs/qnx6/inode.c | 2 +- > fs/reiserfs/super.c | 2 +- > fs/romfs/super.c | 2 +- > fs/squashfs/super.c | 2 +- > fs/sysv/inode.c | 2 +- > fs/ubifs/super.c | 2 +- > fs/udf/super.c | 2 +- > fs/ufs/super.c | 2 +- > fs/vboxsf/super.c | 2 +- > fs/xfs/xfs_icache.c | 2 +- > fs/zonefs/super.c | 2 +- > include/linux/fs.h | 11 + > include/linux/list_lru.h | 17 +- > include/linux/memcontrol.h | 42 ++-- > include/linux/slab.h | 3 + > include/linux/swap.h | 5 +- > include/linux/xarray.h | 9 +- > ipc/mqueue.c | 2 +- > lib/xarray.c | 10 +- > mm/list_lru.c | 423 ++++++++++++++++------------------ > mm/memcontrol.c | 164 +++---------- > mm/shmem.c | 2 +- > mm/slab.c | 39 +++- > mm/slab.h | 25 +- > mm/slob.c | 6 + > mm/slub.c | 42 ++-- > mm/workingset.c | 2 +- > net/socket.c | 2 +- > net/sunrpc/rpc_pipe.c | 2 +- > 76 files changed, 486 insertions(+), 539 deletions(-) >
