To support the use of mTHP with anonymous shmem, add a new sysfs interface
'shmem_enabled' in the '/sys/kernel/mm/transparent_hugepage/hugepages-kB/'
directory for each mTHP to control whether shmem is enabled for that mTHP,
with a value similar to the top level 'shmem_enabled', which can be set to:
"always", "inherit (to inherit the top level setting)", "within_size", "advise",
"never", "deny", "force". These values follow the same semantics as the top
level, except the 'deny' is equivalent to 'never', and 'force' is equivalent
to 'always' to keep compatibility.
By default, PMD-sized hugepages have enabled="inherit" and all other hugepage
sizes have enabled="never" for '/sys/kernel/mm/transparent_hugepage/hugepages-xxkB/shmem_enabled'.
In addition, if top level value is 'force', then only PMD-sized hugepages
have enabled="inherit", otherwise configuration will be failed and vice versa.
That means now we will avoid using non-PMD sized THP to override the global
huge allocation.
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
Documentation/admin-guide/mm/transhuge.rst | 29 +++++++
include/linux/huge_mm.h | 10 +++
mm/huge_memory.c | 11 +--
mm/shmem.c | 96 ++++++++++++++++++++++
4 files changed, 138 insertions(+), 8 deletions(-)
diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
index 076443cc10a6..a28496e15bdb 100644
--- a/Documentation/admin-guide/mm/transhuge.rst
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -332,6 +332,35 @@ deny
force
Force the huge option on for all - very useful for testing;
+Anonymous shmem can also use "multi-size THP" (mTHP) by adding a new sysfs knob
+to control mTHP allocation: /sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/shmem_enabled.
+Its value for each mTHP is essentially consistent with the global setting, except
+for the addition of 'inherit' to ensure compatibility with the global settings.
+always
+ Attempt to allocate <size> huge pages every time we need a new page;
+
+inherit
+ Inherit the top-level "shmem_enabled" value. By default, PMD-sized hugepages
+ have enabled="inherit" and all other hugepage sizes have enabled="never";
+
+never
+ Do not allocate <size> huge pages;
+
+within_size
+ Only allocate <size> huge page if it will be fully within i_size.
+ Also respect fadvise()/madvise() hints;
+
+advise
+ Only allocate <size> huge pages if requested with fadvise()/madvise();
+
+deny
+ Has the same semantics as 'never', now mTHP allocation policy is only
+ used for anonymous shmem and no not override tmpfs.
+
+force
+ Has the same semantics as 'always', now mTHP allocation policy is only
+ used for anonymous shmem and no not override tmpfs.
+
Need of application restart
===========================
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index e49b56c40a11..dbd6b3f56210 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -6,6 +6,7 @@
#include <linux/mm_types.h>
#include <linux/fs.h> /* only for vma_is_dax() */
+#include <linux/kobject.h>
vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf);
int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
@@ -63,6 +64,7 @@ ssize_t single_hugepage_flag_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf,
enum transparent_hugepage_flag flag);
extern struct kobj_attribute shmem_enabled_attr;
+extern struct kobj_attribute thpsize_shmem_enabled_attr;
/*
* Mask of all large folio orders supported for anonymous THP; all orders up to
@@ -265,6 +267,14 @@ unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma,
return __thp_vma_allowable_orders(vma, vm_flags, tva_flags, orders);
}
+struct thpsize {
+ struct kobject kobj;
+ struct list_head node;
+ int order;
+};
+
+#define to_thpsize(kobj) container_of(kobj, struct thpsize, kobj)
+
enum mthp_stat_item {
MTHP_STAT_ANON_FAULT_ALLOC,
MTHP_STAT_ANON_FAULT_FALLBACK,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9efb6fefc391..d3080a8843f2 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -449,14 +449,6 @@ static void thpsize_release(struct kobject *kobj);
static DEFINE_SPINLOCK(huge_anon_orders_lock);
static LIST_HEAD(thpsize_list);
-struct thpsize {
- struct kobject kobj;
- struct list_head node;
- int order;
-};
-
-#define to_thpsize(kobj) container_of(kobj, struct thpsize, kobj)
-
static ssize_t thpsize_enabled_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
@@ -517,6 +509,9 @@ static struct kobj_attribute thpsize_enabled_attr =
static struct attribute *thpsize_attrs[] = {
&thpsize_enabled_attr.attr,
+#ifdef CONFIG_SHMEM
+ &thpsize_shmem_enabled_attr.attr,
+#endif
NULL,
};
diff --git a/mm/shmem.c b/mm/shmem.c
index a383ea9a89a5..59cc26d44344 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -131,6 +131,14 @@ struct shmem_options {
#define SHMEM_SEEN_QUOTA 32
};
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static unsigned long huge_anon_shmem_orders_always __read_mostly;
+static unsigned long huge_anon_shmem_orders_madvise __read_mostly;
+static unsigned long huge_anon_shmem_orders_inherit __read_mostly;
+static unsigned long huge_anon_shmem_orders_within_size __read_mostly;
+static DEFINE_SPINLOCK(huge_anon_shmem_orders_lock);
+#endif
+
#ifdef CONFIG_TMPFS
static unsigned long shmem_default_max_blocks(void)
{
@@ -4687,6 +4695,12 @@ void __init shmem_init(void)
SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
else
shmem_huge = SHMEM_HUGE_NEVER; /* just in case it was patched */
+
+ /*
+ * Default to setting PMD-sized THP to inherit the global setting and
+ * disable all other multi-size THPs, when anonymous shmem uses mTHP.
+ */
+ huge_anon_shmem_orders_inherit = BIT(HPAGE_PMD_ORDER);
#endif
return;
@@ -4746,6 +4760,11 @@ static ssize_t shmem_enabled_store(struct kobject *kobj,
huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
return -EINVAL;
+ /* Do not override huge allocation policy with non-PMD sized mTHP */
+ if (huge == SHMEM_HUGE_FORCE &&
+ huge_anon_shmem_orders_inherit != BIT(HPAGE_PMD_ORDER))
+ return -EINVAL;
+
shmem_huge = huge;
if (shmem_huge > SHMEM_HUGE_DENY)
SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
@@ -4753,6 +4772,83 @@ static ssize_t shmem_enabled_store(struct kobject *kobj,
}
struct kobj_attribute shmem_enabled_attr = __ATTR_RW(shmem_enabled);
+
+static ssize_t thpsize_shmem_enabled_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ int order = to_thpsize(kobj)->order;
+ const char *output;
+
+ if (test_bit(order, &huge_anon_shmem_orders_always))
+ output = "[always] inherit within_size advise never deny [force]";
+ else if (test_bit(order, &huge_anon_shmem_orders_inherit))
+ output = "always [inherit] within_size advise never deny force";
+ else if (test_bit(order, &huge_anon_shmem_orders_within_size))
+ output = "always inherit [within_size] advise never deny force";
+ else if (test_bit(order, &huge_anon_shmem_orders_madvise))
+ output = "always inherit within_size [advise] never deny force";
+ else
+ output = "always inherit within_size advise [never] [deny] force";
+
+ return sysfs_emit(buf, "%s\n", output);
+}
+
+static ssize_t thpsize_shmem_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;
+
+ if (sysfs_streq(buf, "always") || sysfs_streq(buf, "force")) {
+ spin_lock(&huge_anon_shmem_orders_lock);
+ clear_bit(order, &huge_anon_shmem_orders_inherit);
+ clear_bit(order, &huge_anon_shmem_orders_madvise);
+ clear_bit(order, &huge_anon_shmem_orders_within_size);
+ set_bit(order, &huge_anon_shmem_orders_always);
+ spin_unlock(&huge_anon_shmem_orders_lock);
+ } else if (sysfs_streq(buf, "inherit")) {
+ /* Do not override huge allocation policy with non-PMD sized mTHP */
+ if (shmem_huge == SHMEM_HUGE_FORCE &&
+ order != HPAGE_PMD_ORDER)
+ return -EINVAL;
+
+ spin_lock(&huge_anon_shmem_orders_lock);
+ clear_bit(order, &huge_anon_shmem_orders_always);
+ clear_bit(order, &huge_anon_shmem_orders_madvise);
+ clear_bit(order, &huge_anon_shmem_orders_within_size);
+ set_bit(order, &huge_anon_shmem_orders_inherit);
+ spin_unlock(&huge_anon_shmem_orders_lock);
+ } else if (sysfs_streq(buf, "within_size")) {
+ spin_lock(&huge_anon_shmem_orders_lock);
+ clear_bit(order, &huge_anon_shmem_orders_always);
+ clear_bit(order, &huge_anon_shmem_orders_inherit);
+ clear_bit(order, &huge_anon_shmem_orders_madvise);
+ set_bit(order, &huge_anon_shmem_orders_within_size);
+ spin_unlock(&huge_anon_shmem_orders_lock);
+ } else if (sysfs_streq(buf, "madvise")) {
+ spin_lock(&huge_anon_shmem_orders_lock);
+ clear_bit(order, &huge_anon_shmem_orders_always);
+ clear_bit(order, &huge_anon_shmem_orders_inherit);
+ clear_bit(order, &huge_anon_shmem_orders_within_size);
+ set_bit(order, &huge_anon_shmem_orders_madvise);
+ spin_unlock(&huge_anon_shmem_orders_lock);
+ } else if (sysfs_streq(buf, "never") || sysfs_streq(buf, "deny")) {
+ spin_lock(&huge_anon_shmem_orders_lock);
+ clear_bit(order, &huge_anon_shmem_orders_always);
+ clear_bit(order, &huge_anon_shmem_orders_inherit);
+ clear_bit(order, &huge_anon_shmem_orders_within_size);
+ clear_bit(order, &huge_anon_shmem_orders_madvise);
+ spin_unlock(&huge_anon_shmem_orders_lock);
+ } else {
+ ret = -EINVAL;
+ }
+
+ return ret;
+}
+
+struct kobj_attribute thpsize_shmem_enabled_attr =
+ __ATTR(shmem_enabled, 0644, thpsize_shmem_enabled_show, thpsize_shmem_enabled_store);
#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
#else /* !CONFIG_SHMEM */
--
2.39.3
