On Wed, May 11, 2022 at 09:01:40AM +0300, Vasily Averin <vvs@xxxxxxxxxx> wrote: > number bytes $1*$2 sum note call_site > of alloc > allocs > ------------------------------------------------------------ > 1 14448 14448 14448 = percpu_alloc_percpu: > 1 8192 8192 22640 ++ (mem_cgroup_css_alloc+0x54) This requires just adding GFP_KERNEL_ACCOUNT (no new active memcg switch). > 49 128 6272 28912 ++ (__kernfs_new_node+0x4e) > 49 96 4704 33616 ? (simple_xattr_alloc+0x2c) > 49 88 4312 37928 ++ (__kernfs_iattrs+0x56) > 1 4096 4096 42024 ++ (cgroup_mkdir+0xc7) > 1 3840 3840 45864 = percpu_alloc_percpu: > 4 512 2048 47912 + (alloc_fair_sched_group+0x166) > 4 512 2048 49960 + (alloc_fair_sched_group+0x139) > 1 2048 2048 52008 ++ (mem_cgroup_css_alloc+0x109) > " > [1] https://lore.kernel.org/all/1aa4cd22-fcb6-0e8d-a1c6-23661d618864@xxxxxxxxxx/ > = already accounted > ++ to be accounted first > + to be accounted a bit later > > There is no problems with objects allocated in mem_cgroup_alloc(), > they will be accounted to parent's memcg. > However I do not understand how to handle other large objects? > > We could move set_active_memcg(parent) call from mem_cgroup_css_alloc() > to cgroup_apply_control_enable() and handle allocation in all .css_alloc() > > However I need to handle allocations called from cgroup_mkdir() too and > badly understand how to do it properly. If we consent to charge to the creator, the change would be just passing GFP_ACCOUNT at fewer (right) places, wouldn't it? Also, my undertanding of memcgs is that they're not hermetically tight, so I think charging just kernfs_nodes (for dirs and files) provides sufficient bound. Except for, the xattrs, my older notes say: "make kernfs simple_xattr kernel accounted, up to KERNFS_USER_XATTR_SIZE_LIMIT*KERNFS_MAX_USER_XATTRS = 128k * 128 = 16M / inode". HTH, Michal
