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Date: Thu, 11 Apr 2019 16:42:45 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Keith Busch <keith.busch@...el.com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Linux Memory Management List <linux-mm@...ck.org>,
Rafael Wysocki <rafael@...nel.org>,
Dave Hansen <dave.hansen@...el.com>,
Dan Williams <dan.j.williams@...el.com>,
Brice Goglin <Brice.Goglin@...ia.fr>
Subject: Re: [PATCH] hmat: Register attributes for memory hot add
On Tue, Apr 9, 2019 at 11:42 PM Keith Busch <keith.busch@...el.com> wrote:
>
> Some types of memory nodes that HMAT describes may not be online at the
> time we initially parse their nodes' tables. If the node should be set
> to online later, as can happen when using PMEM as RAM after boot, the
> node's attributes will be missing their initiator links and performance.
>
> Regsiter a memory notifier callback and set the memory attributes when
> a node is initially brought online with hot added memory, and don't try
> to register node attributes if the node is not online during initial
> scanning.
>
> Signed-off-by: Keith Busch <keith.busch@...el.com>
> ---
> drivers/acpi/hmat/hmat.c | 63 ++++++++++++++++++++++++++++++++++++++----------
> 1 file changed, 50 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/acpi/hmat/hmat.c b/drivers/acpi/hmat/hmat.c
> index b275016ff648..cf24b885feb5 100644
> --- a/drivers/acpi/hmat/hmat.c
> +++ b/drivers/acpi/hmat/hmat.c
> @@ -14,14 +14,15 @@
> #include <linux/init.h>
> #include <linux/list.h>
> #include <linux/list_sort.h>
> +#include <linux/memory.h>
> #include <linux/node.h>
> #include <linux/sysfs.h>
>
> -static __initdata u8 hmat_revision;
> +static u8 hmat_revision;
>
> -static __initdata LIST_HEAD(targets);
> -static __initdata LIST_HEAD(initiators);
> -static __initdata LIST_HEAD(localities);
> +static LIST_HEAD(targets);
> +static LIST_HEAD(initiators);
> +static LIST_HEAD(localities);
>
> /*
> * The defined enum order is used to prioritize attributes to break ties when
> @@ -41,6 +42,7 @@ struct memory_target {
> unsigned int memory_pxm;
> unsigned int processor_pxm;
> struct node_hmem_attrs hmem_attrs;
> + bool registered;
> };
>
> struct memory_initiator {
> @@ -53,7 +55,7 @@ struct memory_locality {
> struct acpi_hmat_locality *hmat_loc;
> };
>
> -static __init struct memory_initiator *find_mem_initiator(unsigned int cpu_pxm)
> +static struct memory_initiator *find_mem_initiator(unsigned int cpu_pxm)
> {
> struct memory_initiator *initiator;
>
> @@ -63,7 +65,7 @@ static __init struct memory_initiator *find_mem_initiator(unsigned int cpu_pxm)
> return NULL;
> }
>
> -static __init struct memory_target *find_mem_target(unsigned int mem_pxm)
> +static struct memory_target *find_mem_target(unsigned int mem_pxm)
> {
> struct memory_target *target;
>
> @@ -148,7 +150,7 @@ static __init const char *hmat_data_type_suffix(u8 type)
> }
> }
>
> -static __init u32 hmat_normalize(u16 entry, u64 base, u8 type)
> +static u32 hmat_normalize(u16 entry, u64 base, u8 type)
> {
> u32 value;
>
> @@ -183,7 +185,7 @@ static __init u32 hmat_normalize(u16 entry, u64 base, u8 type)
> return value;
> }
>
> -static __init void hmat_update_target_access(struct memory_target *target,
> +static void hmat_update_target_access(struct memory_target *target,
> u8 type, u32 value)
> {
> switch (type) {
> @@ -435,7 +437,7 @@ static __init int srat_parse_mem_affinity(union acpi_subtable_headers *header,
> return 0;
> }
>
> -static __init u32 hmat_initiator_perf(struct memory_target *target,
> +static u32 hmat_initiator_perf(struct memory_target *target,
> struct memory_initiator *initiator,
> struct acpi_hmat_locality *hmat_loc)
> {
> @@ -473,7 +475,7 @@ static __init u32 hmat_initiator_perf(struct memory_target *target,
> hmat_loc->data_type);
> }
>
> -static __init bool hmat_update_best(u8 type, u32 value, u32 *best)
> +static bool hmat_update_best(u8 type, u32 value, u32 *best)
> {
> bool updated = false;
>
> @@ -517,7 +519,7 @@ static int initiator_cmp(void *priv, struct list_head *a, struct list_head *b)
> return ia->processor_pxm - ib->processor_pxm;
> }
>
> -static __init void hmat_register_target_initiators(struct memory_target *target)
> +static void hmat_register_target_initiators(struct memory_target *target)
> {
> static DECLARE_BITMAP(p_nodes, MAX_NUMNODES);
> struct memory_initiator *initiator;
> @@ -577,22 +579,53 @@ static __init void hmat_register_target_initiators(struct memory_target *target)
> }
> }
>
> -static __init void hmat_register_target_perf(struct memory_target *target)
> +static void hmat_register_target_perf(struct memory_target *target)
> {
> unsigned mem_nid = pxm_to_node(target->memory_pxm);
> node_set_perf_attrs(mem_nid, &target->hmem_attrs, 0);
> }
>
> -static __init void hmat_register_targets(void)
> +static void hmat_register_targets(void)
> {
> struct memory_target *target;
>
> list_for_each_entry(target, &targets, node) {
> + if (!node_online(pxm_to_node(target->memory_pxm)))
> + continue;
> +
> hmat_register_target_initiators(target);
> hmat_register_target_perf(target);
> + target->registered = true;
> }
> }
>
> +static int hmat_callback(struct notifier_block *self,
> + unsigned long action, void *arg)
> +{
> + struct memory_notify *mnb = arg;
> + int pxm, nid = mnb->status_change_nid;
> + struct memory_target *target;
> +
> + if (nid == NUMA_NO_NODE || action != MEM_ONLINE)
> + return NOTIFY_OK;
> +
> + pxm = node_to_pxm(nid);
> + target = find_mem_target(pxm);
> + if (!target || target->registered)
> + return NOTIFY_OK;
> +
> + hmat_register_target_initiators(target);
> + hmat_register_target_perf(target);
> + target->registered = true;
> +
> + return NOTIFY_OK;
> +}
This appears to assume that there will never be any races between the
two functions above.
It this guaranteed to be the case?
> +
> +static struct notifier_block hmat_callback_nb = {
> + .notifier_call = hmat_callback,
> + .priority = 2,
> +};
> +
> static __init void hmat_free_structures(void)
> {
> struct memory_target *target, *tnext;
> @@ -658,6 +691,10 @@ static __init int hmat_init(void)
> }
> }
> hmat_register_targets();
> +
> + /* Keep the table and structures if the notifier may use them */
> + if (!register_hotmemory_notifier(&hmat_callback_nb))
> + return 0;
> out_put:
> hmat_free_structures();
> acpi_put_table(tbl);
> --
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