There is no way to set up the defrag options in boot time. And it's
useful to set it up by default instead of making it work by a
systemd/upstart service or put the command to set up defrag inside
/etc/rc.local.

Signed-off-by: Gavin Guo <gavin....@canonical.com>
---
 .../admin-guide/kernel-parameters.txt         | 18 ++++++++
 mm/huge_memory.c                              | 43 +++++++++++++++++++
 mm/khugepaged.c                               | 21 +++++++++
 3 files changed, 82 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt 
b/Documentation/admin-guide/kernel-parameters.txt
index 6253849afac2..a9fd020d78db 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2149,6 +2149,16 @@
        kgdbwait        [KGDB] Stop kernel execution and enter the
                        kernel debugger at the earliest opportunity.
 
+       khugepaged_defrag=
+                       [KNL]
+                       Format: { "0" | "1" }
+                       0 - disable the defrag
+                       1 - enable the defrag
+                       Control the defrag efforts when generating the
+                       transparent hugepages through khugepaged.
+                       See Documentation/admin-guide/mm/transhuge.rst
+                       for more details.
+
        kmac=           [MIPS] korina ethernet MAC address.
                        Configure the RouterBoard 532 series on-chip
                        Ethernet adapter MAC address.
@@ -5146,6 +5156,14 @@
                        See Documentation/admin-guide/mm/transhuge.rst
                        for more details.
 
+       transparent_hugepage_defrag=
+                       [KNL]
+                       Format: [always|defer|defer+madvise|madvise|never]
+                       Control the defrag efforts when generating the
+                       transparent hugepages.
+                       See Documentation/admin-guide/mm/transhuge.rst
+                       for more details.
+
        tsc=            Disable clocksource stability checks for TSC.
                        Format: <string>
                        [x86] reliable: mark tsc clocksource as reliable, this
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 8091b780cd7a..86b20a3a1aac 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -481,6 +481,49 @@ static int __init setup_transparent_hugepage(char *str)
 }
 __setup("transparent_hugepage=", setup_transparent_hugepage);
 
+static int __init setup_transparent_hugepage_defrag(char *str)
+{
+       int ret = 0;
+       if (!str)
+               goto out;
+       if (!strcmp(str, "always")) {
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 
&transparent_hugepage_flags);
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 
&transparent_hugepage_flags);
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 
&transparent_hugepage_flags);
+               set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 
&transparent_hugepage_flags);
+               ret = 1;
+       } else if (!strcmp(str, "defer+madvise")) {
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 
&transparent_hugepage_flags);
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 
&transparent_hugepage_flags);
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 
&transparent_hugepage_flags);
+               set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 
&transparent_hugepage_flags);
+               ret = 1;
+       } else if (!strcmp(str, "defer")) {
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 
&transparent_hugepage_flags);
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 
&transparent_hugepage_flags);
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 
&transparent_hugepage_flags);
+               set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 
&transparent_hugepage_flags);
+               ret = 1;
+       } else if (!strcmp(str, "madvise")) {
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 
&transparent_hugepage_flags);
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 
&transparent_hugepage_flags);
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 
&transparent_hugepage_flags);
+               set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 
&transparent_hugepage_flags);
+               ret = 1;
+       } else if (!strcmp(str, "never")) {
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 
&transparent_hugepage_flags);
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 
&transparent_hugepage_flags);
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 
&transparent_hugepage_flags);
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 
&transparent_hugepage_flags);
+               ret = 1;
+       }
+out:
+       if (!ret)
+               pr_warn("transparent_hugepage_defrag= cannot parse, ignored\n");
+       return ret;
+}
+__setup("transparent_hugepage_defrag=", setup_transparent_hugepage_defrag);
+
 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
 {
        if (likely(vma->vm_flags & VM_WRITE))
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index b043c40a21d4..39bbf2107a23 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -394,6 +394,27 @@ int __init khugepaged_init(void)
        return 0;
 }
 
+static int __init setup_khugepaged_defrag(char *str)
+{
+       int ret = 0;
+       if (!str)
+               goto out;
+       if (!strcmp(str, "0")) {
+               clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG,
+                         &transparent_hugepage_flags);
+               ret = 1;
+       } else if (!strcmp(str, "1")) {
+               set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG,
+                       &transparent_hugepage_flags);
+               ret = 1;
+       }
+out:
+       if (!ret)
+               pr_warn("khugepaged_defrag= cannot parse, ignored\n");
+       return ret;
+}
+__setup("khugepaged_defrag=", setup_khugepaged_defrag);
+
 void __init khugepaged_destroy(void)
 {
        kmem_cache_destroy(mm_slot_cache);
-- 
2.17.1

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