Eric Lee / smarc-ti-linux-kernel

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Commit 83467efbdb7948146581a56cbd683a22a0684bbb

Authored by Naoya Horiguchi
Committed by Linus Torvalds
1 parent c8721bbbdd
Exists in master and in 20 other branches dlt-processor-sdk-linux-03.00.00.04, newt-ti-linux-3.12.y, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.12.10, smarc-ti-linux-3.12.y, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.12.y, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

mm: migrate: check movability of hugepage in unmap_and_move_huge_page() 

Currently hugepage migration works well only for pmd-based hugepages
(mainly due to lack of testing,) so we had better not enable migration of
other levels of hugepages until we are ready for it.

Some users of hugepage migration (mbind, move_pages, and migrate_pages) do
page table walk and check pud/pmd_huge() there, so they are safe.  But the
other users (softoffline and memory hotremove) don't do this, so without
this patch they can try to migrate unexpected types of hugepages.

To prevent this, we introduce hugepage_migration_support() as an
architecture dependent check of whether hugepage are implemented on a pmd
basis or not.  And on some architecture multiple sizes of hugepages are
available, so hugepage_migration_support() also checks hugepage size.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 13 changed files with 85 additions and 0 deletions Side-by-side Diff

arch/arm/mm/hugetlbpage.c
Diff comments   View file @ 83467ef
... ... @@ -56,4 +56,9 @@
56 56 {
57 57 return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
58 58 }
  59 +
  60 +int pmd_huge_support(void)
  61 +{
  62 + return 1;
  63 +}
arch/arm64/mm/hugetlbpage.c
Diff comments   View file @ 83467ef
... ... @@ -54,6 +54,11 @@
54 54 return !(pud_val(pud) & PUD_TABLE_BIT);
55 55 }
56 56  
  57 +int pmd_huge_support(void)
  58 +{
  59 + return 1;
  60 +}
  61 +
57 62 static __init int setup_hugepagesz(char *opt)
58 63 {
59 64 unsigned long ps = memparse(opt, &opt);
arch/ia64/mm/hugetlbpage.c
Diff comments   View file @ 83467ef
... ... @@ -114,6 +114,11 @@
114 114 return 0;
115 115 }
116 116  
  117 +int pmd_huge_support(void)
  118 +{
  119 + return 0;
  120 +}
  121 +
117 122 struct page *
118 123 follow_huge_pmd(struct mm_struct *mm, unsigned long address, pmd_t *pmd, int write)
119 124 {
arch/metag/mm/hugetlbpage.c
Diff comments   View file @ 83467ef
... ... @@ -110,6 +110,11 @@
110 110 return 0;
111 111 }
112 112  
  113 +int pmd_huge_support(void)
  114 +{
  115 + return 1;
  116 +}
  117 +
113 118 struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
114 119 pmd_t *pmd, int write)
115 120 {
arch/mips/mm/hugetlbpage.c
Diff comments   View file @ 83467ef
... ... @@ -85,6 +85,11 @@
85 85 return (pud_val(pud) & _PAGE_HUGE) != 0;
86 86 }
87 87  
  88 +int pmd_huge_support(void)
  89 +{
  90 + return 1;
  91 +}
  92 +
88 93 struct page *
89 94 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
90 95 pmd_t *pmd, int write)
arch/powerpc/mm/hugetlbpage.c
Diff comments   View file @ 83467ef
... ... @@ -86,6 +86,11 @@
86 86 */
87 87 return ((pgd_val(pgd) & 0x3) != 0x0);
88 88 }
  89 +
  90 +int pmd_huge_support(void)
  91 +{
  92 + return 1;
  93 +}
89 94 #else
90 95 int pmd_huge(pmd_t pmd)
91 96 {
... ... @@ -98,6 +103,11 @@
98 103 }
99 104  
100 105 int pgd_huge(pgd_t pgd)
  106 +{
  107 + return 0;
  108 +}
  109 +
  110 +int pmd_huge_support(void)
101 111 {
102 112 return 0;
103 113 }
arch/s390/mm/hugetlbpage.c
Diff comments   View file @ 83467ef
... ... @@ -223,6 +223,11 @@
223 223 return 0;
224 224 }
225 225  
  226 +int pmd_huge_support(void)
  227 +{
  228 + return 1;
  229 +}
  230 +
226 231 struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
227 232 pmd_t *pmdp, int write)
228 233 {
arch/sh/mm/hugetlbpage.c
Diff comments   View file @ 83467ef
... ... @@ -83,6 +83,11 @@
83 83 return 0;
84 84 }
85 85  
  86 +int pmd_huge_support(void)
  87 +{
  88 + return 0;
  89 +}
  90 +
86 91 struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
87 92 pmd_t *pmd, int write)
88 93 {
arch/sparc/mm/hugetlbpage.c
Diff comments   View file @ 83467ef
... ... @@ -234,6 +234,11 @@
234 234 return 0;
235 235 }
236 236  
  237 +int pmd_huge_support(void)
  238 +{
  239 + return 0;
  240 +}
  241 +
237 242 struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
238 243 pmd_t *pmd, int write)
239 244 {
arch/tile/mm/hugetlbpage.c
Diff comments   View file @ 83467ef
... ... @@ -166,6 +166,11 @@
166 166 return !!(pud_val(pud) & _PAGE_HUGE_PAGE);
167 167 }
168 168  
  169 +int pmd_huge_support(void)
  170 +{
  171 + return 1;
  172 +}
  173 +
169 174 struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
170 175 pmd_t *pmd, int write)
171 176 {
arch/x86/mm/hugetlbpage.c
Diff comments   View file @ 83467ef
... ... @@ -59,6 +59,10 @@
59 59 return NULL;
60 60 }
61 61  
  62 +int pmd_huge_support(void)
  63 +{
  64 + return 0;
  65 +}
62 66 #else
63 67  
64 68 struct page *
... ... @@ -77,6 +81,10 @@
77 81 return !!(pud_val(pud) & _PAGE_PSE);
78 82 }
79 83  
  84 +int pmd_huge_support(void)
  85 +{
  86 + return 1;
  87 +}
80 88 #endif
81 89  
82 90 /* x86_64 also uses this file */
include/linux/hugetlb.h
Diff comments   View file @ 83467ef
... ... @@ -381,6 +381,16 @@
381 381  
382 382 extern void dissolve_free_huge_pages(unsigned long start_pfn,
383 383 unsigned long end_pfn);
  384 +int pmd_huge_support(void);
  385 +/*
  386 + * Currently hugepage migration is enabled only for pmd-based hugepage.
  387 + * This function will be updated when hugepage migration is more widely
  388 + * supported.
  389 + */
  390 +static inline int hugepage_migration_support(struct hstate *h)
  391 +{
  392 + return pmd_huge_support() && (huge_page_shift(h) == PMD_SHIFT);
  393 +}
384 394  
385 395 #else /* CONFIG_HUGETLB_PAGE */
386 396 struct hstate {};
... ... @@ -409,6 +419,8 @@
409 419 return page->index;
410 420 }
411 421 #define dissolve_free_huge_pages(s, e) do {} while (0)
  422 +#define pmd_huge_support() 0
  423 +#define hugepage_migration_support(h) 0
412 424 #endif /* CONFIG_HUGETLB_PAGE */
413 425  
414 426 #endif /* _LINUX_HUGETLB_H */
... ... @@ -949,6 +949,16 @@
949 949 struct page *new_hpage = get_new_page(hpage, private, &result);
950 950 struct anon_vma *anon_vma = NULL;
951 951  
  952 + /*
  953 + * Movability of hugepages depends on architectures and hugepage size.
  954 + * This check is necessary because some callers of hugepage migration
  955 + * like soft offline and memory hotremove don't walk through page
  956 + * tables or check whether the hugepage is pmd-based or not before
  957 + * kicking migration.
  958 + */
  959 + if (!hugepage_migration_support(page_hstate(hpage)))
  960 + return -ENOSYS;
  961 +
952 962 if (!new_hpage)
953 963 return -ENOMEM;
954 964