From: Oscar Salvador <osalvador@xxxxxxx>
v1 -> v2:
- Address feedback from Pavel
- Re-write patch4 his way, as it is better
- Add Reviewed-by from Pavel
---
This patchset refactors/clean ups node_states_check_changes_online/offline
functions together with node_states_set/clear_node.
The main reason behind this patchset is that currently, these
functions are suboptimal and confusing.
For example, they contain wrong statements like:
if (N_MEMORY == N_NORMAL_MEMORY)
if (N_MEMORY =! N_NORMAL_MEMORY)
if (N_MEMORY != N_HIGH_MEMORY)
if (N_MEMORY == N_HIGH_MEMORY)
These comparasions are wrong, as N_MEMORY will never be equal
to either N_NORMAL_MEMORY or N_HIGH_MEMORY.
Although the statements do not "affect" the flow because in the way
they are placed, they are completely wrong and confusing.
I caught another misuse of this in [1].
Another thing that this patchset addresses is the fact that
some functions get called twice, or even unconditionally, without
any need.
Examples of this are:
- node_states_set_node()->node_set_state(node, N_MEMORY)
* node_states_set_node() gets called whenever we online pages,
so we end up calling node_set_state(node, N_MEMORY) everytime.
To avoid this, we should check if the node is already in node_state[N_MEMORY].
- node_states_set_node()->node_set_state(node, N_HIGH_MEMORY)
* On !CONFIG_HIGH_MEMORY, N_HIGH_MEMORY == N_NORMAL_MEMORY,
but the current code sets:
status_change_nid_high = status_change_nid_normal
This means that we will call node_set_state(node, N_NORMAL_MEMORY) twice.
The fix here is to set status_change_nid_normal = -1 on such systems,
so we skip the second call.
[1] https://patchwork.kernel.org/patch/10579155/
Oscar Salvador (4):
mm/memory_hotplug: Spare unnecessary calls to node_set_state
mm/memory_hotplug: Tidy up node_states_clear_node
mm/memory_hotplug: Simplify node_states_check_changes_online
mm/memory_hotplug: Clean up node_states_check_changes_offline
mm/memory_hotplug.c | 146 ++++++++++++++--------------------------------------
1 file changed, 40 insertions(+), 106 deletions(-)
--
2.13.6
