mm: override mTHP "enabled" defaults at kernel cmdline

Add thp_anon= cmdline parameter to allow specifying the default enablement
of each supported anon THP size.  The parameter accepts the following
format and can be provided multiple times to configure each size:

thp_anon=<size>,<size>[KMG]:<value>;<size>-<size>[KMG]:<value>

An example:

thp_anon=16K-64K:always;128K,512K:inherit;256K:madvise;1M-2M:never

See Documentation/admin-guide/mm/transhuge.rst for more details.

Configuring the defaults at boot time is useful to allow early user
space to take advantage of mTHP before its been configured through
sysfs.

Link: https://lkml.kernel.org/r/20240814020247.67297-1-21cnbao@gmail.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Co-developed-by: Barry Song <v-songbaohua@oppo.com>
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <ioworker0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index f0057bac20fba1776f9836bdb377b3420c296dfe..d0d141d5063868acb13cf6539e53cc746a426fcf 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6629,6 +6629,15 @@
                        <deci-seconds>: poll all this frequency
                        0: no polling (default)
 
+       thp_anon=       [KNL]
+                       Format: <size>,<size>[KMG]:<state>;<size>-<size>[KMG]:<state>
+                       state is one of "always", "madvise", "never" or "inherit".
+                       Can be used to control the default behavior of the
+                       system with respect to anonymous transparent hugepages.
+                       Can be used multiple times for multiple anon THP sizes.
+                       See Documentation/admin-guide/mm/transhuge.rst for more
+                       details.
+
        threadirqs      [KNL,EARLY]
                        Force threading of all interrupt handlers except those
                        marked explicitly IRQF_NO_THREAD.

diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
index 058485daf1860de7a600e778affa3fb45bf613bd..471ece9bd25566e371cc747000663ca27ce38bec 100644 (file)
--- a/Documentation/admin-guide/mm/transhuge.rst
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -284,13 +284,36 @@ that THP is shared. Exceeding the number would block the collapse::
 
 A higher value may increase memory footprint for some workloads.
 
-Boot parameter
-==============
-
-You can change the sysfs boot time defaults of Transparent Hugepage
-Support by passing the parameter ``transparent_hugepage=always`` or
-``transparent_hugepage=madvise`` or ``transparent_hugepage=never``
-to the kernel command line.
+Boot parameters
+===============
+
+You can change the sysfs boot time default for the top-level "enabled"
+control by passing the parameter ``transparent_hugepage=always`` or
+``transparent_hugepage=madvise`` or ``transparent_hugepage=never`` to the
+kernel command line.
+
+Alternatively, each supported anonymous THP size can be controlled by
+passing ``thp_anon=<size>,<size>[KMG]:<state>;<size>-<size>[KMG]:<state>``,
+where ``<size>`` is the THP size and ``<state>`` is one of ``always``,
+``madvise``, ``never`` or ``inherit``.
+
+For example, the following will set 16K, 32K, 64K THP to ``always``,
+set 128K, 512K to ``inherit``, set 256K to ``madvise`` and 1M, 2M
+to ``never``::
+
+       thp_anon=16K-64K:always;128K,512K:inherit;256K:madvise;1M-2M:never
+
+``thp_anon=`` may be specified multiple times to configure all THP sizes as
+required. If ``thp_anon=`` is specified at least once, any anon THP sizes
+not explicitly configured on the command line are implicitly set to
+``never``.
+
+``transparent_hugepage`` setting only affects the global toggle. If
+``thp_anon`` is not specified, PMD_ORDER THP will default to ``inherit``.
+However, if a valid ``thp_anon`` setting is provided by the user, the
+PMD_ORDER THP policy will be overridden. If the policy for PMD_ORDER
+is not defined within a valid ``thp_anon``, its policy will default to
+``never``.
 
 Hugepages in tmpfs/shmem
 ========================

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index d90d6e94a80036debe7b097abf42f2226ed7d2bc..d32ade9900599ccf1f2ce6b0d0cd57fe40d05103 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -81,6 +81,7 @@ unsigned long huge_zero_pfn __read_mostly = ~0UL;
 unsigned long huge_anon_orders_always __read_mostly;
 unsigned long huge_anon_orders_madvise __read_mostly;
 unsigned long huge_anon_orders_inherit __read_mostly;
+static bool anon_orders_configured;
 
 unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
                                         unsigned long vm_flags,
@@ -733,7 +734,10 @@ static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
         * disable all other sizes. powerpc's PMD_ORDER isn't a compile-time
         * constant so we have to do this here.
         */
-       huge_anon_orders_inherit = BIT(PMD_ORDER);
+       if (!anon_orders_configured) {
+               huge_anon_orders_inherit = BIT(PMD_ORDER);
+               anon_orders_configured = true;
+       }
 
        *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
        if (unlikely(!*hugepage_kobj)) {
@@ -918,6 +922,96 @@ out:
 }
 __setup("transparent_hugepage=", setup_transparent_hugepage);
 
+static inline int get_order_from_str(const char *size_str)
+{
+       unsigned long size;
+       char *endptr;
+       int order;
+
+       size = memparse(size_str, &endptr);
+       order = fls(size >> PAGE_SHIFT) - 1;
+       if ((1 << order) & ~THP_ORDERS_ALL_ANON) {
+               pr_err("invalid size %s(order %d) in thp_anon boot parameter\n",
+                       size_str, order);
+               return -EINVAL;
+       }
+
+       return order;
+}
+
+static char str_dup[PAGE_SIZE] __meminitdata;
+static int __init setup_thp_anon(char *str)
+{
+       char *token, *range, *policy, *subtoken;
+       unsigned long always, inherit, madvise;
+       char *start_size, *end_size;
+       int start, end;
+       char *p;
+
+       if (!str || strlen(str) + 1 > PAGE_SIZE)
+               goto err;
+       strcpy(str_dup, str);
+
+       always = huge_anon_orders_always;
+       madvise = huge_anon_orders_madvise;
+       inherit = huge_anon_orders_inherit;
+       p = str_dup;
+       while ((token = strsep(&p, ";")) != NULL) {
+               range = strsep(&token, ":");
+               policy = token;
+
+               if (!policy)
+                       goto err;
+
+               while ((subtoken = strsep(&range, ",")) != NULL) {
+                       if (strchr(subtoken, '-')) {
+                               start_size = strsep(&subtoken, "-");
+                               end_size = subtoken;
+
+                               start = get_order_from_str(start_size);
+                               end = get_order_from_str(end_size);
+                       } else {
+                               start = end = get_order_from_str(subtoken);
+                       }
+
+                       if (start < 0 || end < 0 || start > end)
+                               goto err;
+
+                       if (!strcmp(policy, "always")) {
+                               bitmap_set(&always, start, end - start + 1);
+                               bitmap_clear(&inherit, start, end - start + 1);
+                               bitmap_clear(&madvise, start, end - start + 1);
+                       } else if (!strcmp(policy, "madvise")) {
+                               bitmap_set(&madvise, start, end - start + 1);
+                               bitmap_clear(&inherit, start, end - start + 1);
+                               bitmap_clear(&always, start, end - start + 1);
+                       } else if (!strcmp(policy, "inherit")) {
+                               bitmap_set(&inherit, start, end - start + 1);
+                               bitmap_clear(&madvise, start, end - start + 1);
+                               bitmap_clear(&always, start, end - start + 1);
+                       } else if (!strcmp(policy, "never")) {
+                               bitmap_clear(&inherit, start, end - start + 1);
+                               bitmap_clear(&madvise, start, end - start + 1);
+                               bitmap_clear(&always, start, end - start + 1);
+                       } else {
+                               pr_err("invalid policy %s in thp_anon boot parameter\n", policy);
+                               goto err;
+                       }
+               }
+       }
+
+       huge_anon_orders_always = always;
+       huge_anon_orders_madvise = madvise;
+       huge_anon_orders_inherit = inherit;
+       anon_orders_configured = true;
+       return 1;
+
+err:
+       pr_warn("thp_anon=%s: cannot parse, ignored\n", str);
+       return 0;
+}
+__setup("thp_anon=", setup_thp_anon);
+
 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
 {
        if (likely(vma->vm_flags & VM_WRITE))