cgroup/dmem: Don't open-code css_for_each_descendant_pre

The current implementation has a bug: If the current css doesn't
contain any pool that is a descendant of the "pool" (i.e. when
found_descend

cgroup/dmem: Don't open-code css_for_each_descendant_pre

The current implementation has a bug: If the current css doesn't
contain any pool that is a descendant of the "pool" (i.e. when
found_descendant == false), then "pool" will point to some unrelated
pool. If the current css has a child, we'll overwrite parent_pool with
this unrelated pool on the next iteration.

Since we can just check whether a pool refers to the same region to
determine whether or not it's related, all the additional pool tracking
is unnecessary, so just switch to using css_for_each_descendant_pre for
traversal.

Fixes: b168ed458dde ("kernel/cgroup: Add "dmem" memory accounting cgroup")
Signed-off-by: Friedrich Vock <[email protected]>
Reviewed-by: Maarten Lankhorst <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Maarten Lankhorst <[email protected]>

show more ...

cgroup/dmem: Fix parameters documentation

During the dmem cgroup development, the parameters to the
dmem_cgroup_state_evict_valuable() and dmem_cgroup_try_charge() were
changed, but the documentatio

cgroup/dmem: Fix parameters documentation

During the dmem cgroup development, the parameters to the
dmem_cgroup_state_evict_valuable() and dmem_cgroup_try_charge() were
changed, but the documentation wasn't adjusted accordingly.

This results in a documentation build warning. Adjust the documentation
to reflect what the final functions parameters are.

Fixes: b168ed458dde ("kernel/cgroup: Add "dmem" memory accounting cgroup")
Reported-by: Stephen Rothwell <[email protected]>
Closes: https://lore.kernel.org/r/[email protected]/
Acked-by: Tejun Heo <[email protected]>
Reviewed-by: Simona Vetter <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Maxime Ripard <[email protected]>

show more ...

kernel/cgroup: Remove the unused variable climit

Variable climit is not effectively used, so delete it.

kernel/cgroup/dmem.c:302:23: warning: variable ‘climit’ set but not used.

Reported-by: Abaci

kernel/cgroup: Remove the unused variable climit

Variable climit is not effectively used, so delete it.

kernel/cgroup/dmem.c:302:23: warning: variable ‘climit’ set but not used.

Reported-by: Abaci Robot <[email protected]>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=13512
Signed-off-by: Jiapeng Chong <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Maxime Ripard <[email protected]>

show more ...

kernel/cgroup: Add "dmem" memory accounting cgroup

This code is based on the RDMA and misc cgroup initially, but now
uses page_counter. It uses the same min/low/max semantics as the memory
cgroup as

kernel/cgroup: Add "dmem" memory accounting cgroup

This code is based on the RDMA and misc cgroup initially, but now
uses page_counter. It uses the same min/low/max semantics as the memory
cgroup as a result.

There's a small mismatch as TTM uses u64, and page_counter long pages.
In practice it's not a problem. 32-bits systems don't really come with
>=4GB cards and as long as we're consistently wrong with units, it's
fine. The device page size may not be in the same units as kernel page
size, and each region might also have a different page size (VRAM vs GART
for example).

The interface is simple:
- Call dmem_cgroup_register_region()
- Use dmem_cgroup_try_charge to check if you can allocate a chunk of memory,
use dmem_cgroup__uncharge when freeing it. This may return an error code,
or -EAGAIN when the cgroup limit is reached. In that case a reference
to the limiting pool is returned.
- The limiting cs can be used as compare function for
dmem_cgroup_state_evict_valuable.
- After having evicted enough, drop reference to limiting cs with
dmem_cgroup_pool_state_put.

This API allows you to limit device resources with cgroups.
You can see the supported cards in /sys/fs/cgroup/dmem.capacity
You need to echo +dmem to cgroup.subtree_control, and then you can
partition device memory.

Co-developed-by: Friedrich Vock <[email protected]>
Signed-off-by: Friedrich Vock <[email protected]>
Co-developed-by: Maxime Ripard <[email protected]>
Signed-off-by: Maarten Lankhorst <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Maxime Ripard <[email protected]>

show more ...