On Thu, Aug 8, 2024 at 11:19 PM Ryan Roberts <ryan.roberts@xxxxxxx> wrote:
>
> Previously we had a situation where shmem mTHP controls and stats were
> not exposed for some supported sizes and were exposed for some
> unsupported sizes. So let's clean that up.
>
> Anon mTHP can support all large orders [2, PMD_ORDER]. But shmem can
> support all large orders [1, MAX_PAGECACHE_ORDER]. However, per-size
> shmem controls and stats were previously being exposed for all the anon
> mTHP orders, meaning order-1 was not present, and for arm64 64K base
> pages, orders 12 and 13 were exposed but were not supported internally.
>
> Tidy this all up by defining ctrl and stats attribute groups for anon
> and file separately. Anon ctrl and stats groups are populated for all
> orders in THP_ORDERS_ALL_ANON and file ctrl and stats groups are
> populated for all orders in THP_ORDERS_ALL_FILE_DEFAULT.
>
> Additionally, create "any" ctrl and stats attribute groups which are
> populated for all orders in (THP_ORDERS_ALL_ANON |
> THP_ORDERS_ALL_FILE_DEFAULT). swpout stats use this since they apply to
> anon and shmem.
This passage is a bit confusing to me. I'm not sure whether it's about
creating any control and stats for both file and anon, or creating them
separately depending on the situation. However, the previous passage
mentions that file and anon create control and stats separately based
on different orders, and the orders they create might differ.
But after running your patches, I understood it. For instance, I'm now
seeing 8kB folder that didn't exist before:
/sys/kernel/mm/transparent_hugepage # ls -l
drwxr-xr-x 3 root root 0 Aug 8 22:01 hugepages-1024kB
...
drwxr-xr-x 3 root root 0 Aug 8 22:01 hugepages-8kB
drwxr-xr-x 2 root root 0 Aug 8 22:01 khugepaged
...
Then, when I entered the 8kB folder, I found 'shmem_enabled'
but not 'enabled' for anon:
/sys/kernel/mm/transparent_hugepage/hugepages-8kB # ls
shmem_enabled stats
However, in the 16kB folder, I found both:
/sys/kernel/mm/transparent_hugepage/hugepages-16kB # ls
enabled shmem_enabled stats
In the 8kB 'stats,' I see 'shmem_alloc' but not 'anon_alloc.' Since
both shmem and anon require swapout, I am seeing 'swpout' and
'swpout_fallback':
/sys/kernel/mm/transparent_hugepage/hugepages-8kB/stats # ls
shmem_alloc shmem_fallback shmem_fallback_charge swpout
swpout_fallback
Everything observed seems to meet expectations, so:
Tested-by: Barry Song <baohua@xxxxxxxxxx>
>
> The side-effect of all this is that different hugepage-*kB directories
> contain different sets of controls and stats, depending on which memory
> types support that size. This approach is preferred over the
> alternative, which is to populate dummy controls and stats for memory
> types that do not support a given size.
>
> Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
> ---
> mm/huge_memory.c | 144 +++++++++++++++++++++++++++++++++++++----------
> 1 file changed, 114 insertions(+), 30 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 0c3075ee00012..082d86b7c6c2f 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -482,8 +482,8 @@ static void thpsize_release(struct kobject *kobj);
> static DEFINE_SPINLOCK(huge_anon_orders_lock);
> static LIST_HEAD(thpsize_list);
>
> -static ssize_t thpsize_enabled_show(struct kobject *kobj,
> - struct kobj_attribute *attr, char *buf)
> +static ssize_t anon_enabled_show(struct kobject *kobj,
> + struct kobj_attribute *attr, char *buf)
> {
> int order = to_thpsize(kobj)->order;
> const char *output;
> @@ -500,9 +500,9 @@ static ssize_t thpsize_enabled_show(struct kobject *kobj,
> return sysfs_emit(buf, "%s\n", output);
> }
>
> -static ssize_t thpsize_enabled_store(struct kobject *kobj,
> - struct kobj_attribute *attr,
> - const char *buf, size_t count)
> +static ssize_t anon_enabled_store(struct kobject *kobj,
> + struct kobj_attribute *attr,
> + const char *buf, size_t count)
> {
> int order = to_thpsize(kobj)->order;
> ssize_t ret = count;
> @@ -544,19 +544,35 @@ static ssize_t thpsize_enabled_store(struct kobject *kobj,
> return ret;
> }
>
> -static struct kobj_attribute thpsize_enabled_attr =
> - __ATTR(enabled, 0644, thpsize_enabled_show, thpsize_enabled_store);
> +static struct kobj_attribute anon_enabled_attr =
> + __ATTR(enabled, 0644, anon_enabled_show, anon_enabled_store);
>
> -static struct attribute *thpsize_attrs[] = {
> - &thpsize_enabled_attr.attr,
> +static struct attribute *anon_ctrl_attrs[] = {
> + &anon_enabled_attr.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group anon_ctrl_attr_grp = {
> + .attrs = anon_ctrl_attrs,
> +};
> +
> +static struct attribute *file_ctrl_attrs[] = {
> #ifdef CONFIG_SHMEM
> &thpsize_shmem_enabled_attr.attr,
> #endif
> NULL,
> };
>
> -static const struct attribute_group thpsize_attr_group = {
> - .attrs = thpsize_attrs,
> +static const struct attribute_group file_ctrl_attr_grp = {
> + .attrs = file_ctrl_attrs,
> +};
> +
> +static struct attribute *any_ctrl_attrs[] = {
> + NULL,
> +};
> +
> +static const struct attribute_group any_ctrl_attr_grp = {
> + .attrs = any_ctrl_attrs,
> };
>
> static const struct kobj_type thpsize_ktype = {
> @@ -595,64 +611,132 @@ DEFINE_MTHP_STAT_ATTR(anon_fault_fallback, MTHP_STAT_ANON_FAULT_FALLBACK);
> DEFINE_MTHP_STAT_ATTR(anon_fault_fallback_charge, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE);
> DEFINE_MTHP_STAT_ATTR(swpout, MTHP_STAT_SWPOUT);
> DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK);
> +#ifdef CONFIG_SHMEM
> DEFINE_MTHP_STAT_ATTR(shmem_alloc, MTHP_STAT_SHMEM_ALLOC);
> DEFINE_MTHP_STAT_ATTR(shmem_fallback, MTHP_STAT_SHMEM_FALLBACK);
> DEFINE_MTHP_STAT_ATTR(shmem_fallback_charge, MTHP_STAT_SHMEM_FALLBACK_CHARGE);
> +#endif
> DEFINE_MTHP_STAT_ATTR(split, MTHP_STAT_SPLIT);
> DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED);
> DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED);
>
> -static struct attribute *stats_attrs[] = {
> +static struct attribute *anon_stats_attrs[] = {
> &anon_fault_alloc_attr.attr,
> &anon_fault_fallback_attr.attr,
> &anon_fault_fallback_charge_attr.attr,
> +#ifndef CONFIG_SHMEM
> &swpout_attr.attr,
> &swpout_fallback_attr.attr,
> - &shmem_alloc_attr.attr,
> - &shmem_fallback_attr.attr,
> - &shmem_fallback_charge_attr.attr,
> +#endif
> &split_attr.attr,
> &split_failed_attr.attr,
> &split_deferred_attr.attr,
> NULL,
> };
>
> -static struct attribute_group stats_attr_group = {
> +static struct attribute_group anon_stats_attr_grp = {
> + .name = "stats",
> + .attrs = anon_stats_attrs,
> +};
> +
> +static struct attribute *file_stats_attrs[] = {
> +#ifdef CONFIG_SHMEM
> + &shmem_alloc_attr.attr,
> + &shmem_fallback_attr.attr,
> + &shmem_fallback_charge_attr.attr,
> +#endif
> + NULL,
> +};
> +
> +static struct attribute_group file_stats_attr_grp = {
> + .name = "stats",
> + .attrs = file_stats_attrs,
> +};
> +
> +static struct attribute *any_stats_attrs[] = {
> +#ifdef CONFIG_SHMEM
> + &swpout_attr.attr,
> + &swpout_fallback_attr.attr,
> +#endif
> + NULL,
> +};
> +
> +static struct attribute_group any_stats_attr_grp = {
> .name = "stats",
> - .attrs = stats_attrs,
> + .attrs = any_stats_attrs,
> };
>
> +static int sysfs_add_group(struct kobject *kobj,
> + const struct attribute_group *grp)
> +{
> + int ret = -ENOENT;
> +
> + /*
> + * If the group is named, try to merge first, assuming the subdirectory
> + * was already created. This avoids the warning emitted by
> + * sysfs_create_group() if the directory already exists.
> + */
> + if (grp->name)
> + ret = sysfs_merge_group(kobj, grp);
> + if (ret)
> + ret = sysfs_create_group(kobj, grp);
> +
> + return ret;
> +}
> +
> static struct thpsize *thpsize_create(int order, struct kobject *parent)
> {
> unsigned long size = (PAGE_SIZE << order) / SZ_1K;
> struct thpsize *thpsize;
> - int ret;
> + int ret = -ENOMEM;
>
> thpsize = kzalloc(sizeof(*thpsize), GFP_KERNEL);
> if (!thpsize)
> - return ERR_PTR(-ENOMEM);
> + goto err;
> +
> + thpsize->order = order;
>
> ret = kobject_init_and_add(&thpsize->kobj, &thpsize_ktype, parent,
> "hugepages-%lukB", size);
> if (ret) {
> kfree(thpsize);
> - return ERR_PTR(ret);
> + goto err;
> }
>
> - ret = sysfs_create_group(&thpsize->kobj, &thpsize_attr_group);
> - if (ret) {
> - kobject_put(&thpsize->kobj);
> - return ERR_PTR(ret);
> +
> + ret = sysfs_add_group(&thpsize->kobj, &any_ctrl_attr_grp);
> + if (ret)
> + goto err_put;
> +
> + ret = sysfs_add_group(&thpsize->kobj, &any_stats_attr_grp);
> + if (ret)
> + goto err_put;
> +
> + if (BIT(order) & THP_ORDERS_ALL_ANON) {
> + ret = sysfs_add_group(&thpsize->kobj, &anon_ctrl_attr_grp);
> + if (ret)
> + goto err_put;
> +
> + ret = sysfs_add_group(&thpsize->kobj, &anon_stats_attr_grp);
> + if (ret)
> + goto err_put;
> }
>
> - ret = sysfs_create_group(&thpsize->kobj, &stats_attr_group);
> - if (ret) {
> - kobject_put(&thpsize->kobj);
> - return ERR_PTR(ret);
> + if (BIT(order) & THP_ORDERS_ALL_FILE_DEFAULT) {
> + ret = sysfs_add_group(&thpsize->kobj, &file_ctrl_attr_grp);
> + if (ret)
> + goto err_put;
> +
> + ret = sysfs_add_group(&thpsize->kobj, &file_stats_attr_grp);
> + if (ret)
> + goto err_put;
> }
>
> - thpsize->order = order;
> return thpsize;
> +err_put:
> + kobject_put(&thpsize->kobj);
> +err:
> + return ERR_PTR(ret);
> }
>
> static void thpsize_release(struct kobject *kobj)
> @@ -692,7 +776,7 @@ static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
> goto remove_hp_group;
> }
>
> - orders = THP_ORDERS_ALL_ANON;
> + orders = THP_ORDERS_ALL_ANON | THP_ORDERS_ALL_FILE_DEFAULT;
> order = highest_order(orders);
> while (orders) {
> thpsize = thpsize_create(order, *hugepage_kobj);
> --
> 2.43.0
>
Thanks
Barry
