The kcompactd threads should respect the housekeeping mask for kthreads (HK_TYPE_KTHREAD) to avoid running on isolated CPUs. Currently, they are created without explicit affinity constraints beyond the node preference.
Add housekeeping_affine() to kcompactd_run() to set initial affinity, and register a housekeeping notifier to update kcompactd affinity when the HK_TYPE_KTHREAD mask is changed at runtime. Signed-off-by: Qiliang Yuan <[email protected]> Signed-off-by: Qiliang Yuan <[email protected]> --- mm/compaction.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/mm/compaction.c b/mm/compaction.c index 1e8f8eca318c..495106d970f1 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -24,6 +24,7 @@ #include <linux/page_owner.h> #include <linux/psi.h> #include <linux/cpuset.h> +#include <linux/sched/isolation.h> #include "internal.h" #ifdef CONFIG_COMPACTION @@ -3246,6 +3247,7 @@ void __meminit kcompactd_run(int nid) pr_err("Failed to start kcompactd on node %d\n", nid); pgdat->kcompactd = NULL; } else { + housekeeping_affine(pgdat->kcompactd, HK_TYPE_KTHREAD); wake_up_process(pgdat->kcompactd); } } @@ -3320,6 +3322,29 @@ static const struct ctl_table vm_compaction[] = { }, }; +static int kcompactd_housekeeping_reconfigure(struct notifier_block *nb, + unsigned long action, void *data) +{ + unsigned int type = (unsigned long)data; + + if (action == HK_UPDATE_MASK && type == HK_TYPE_KTHREAD) { + int nid; + + for_each_node_state(nid, N_MEMORY) { + pg_data_t *pgdat = NODE_DATA(nid); + + if (pgdat->kcompactd) + housekeeping_affine(pgdat->kcompactd, HK_TYPE_KTHREAD); + } + } + + return NOTIFY_OK; +} + +static struct notifier_block kcompactd_housekeeping_nb = { + .notifier_call = kcompactd_housekeeping_reconfigure, +}; + static int __init kcompactd_init(void) { int nid; @@ -3327,6 +3352,7 @@ static int __init kcompactd_init(void) for_each_node_state(nid, N_MEMORY) kcompactd_run(nid); register_sysctl_init("vm", vm_compaction); + housekeeping_register_notifier(&kcompactd_housekeeping_nb); return 0; } subsys_initcall(kcompactd_init) -- 2.51.0
