2 * Generic hugetlb support.
3 * (C) William Irwin, April 2004
6 #include <linux/list.h>
7 #include <linux/init.h>
8 #include <linux/module.h>
10 #include <linux/sysctl.h>
11 #include <linux/highmem.h>
12 #include <linux/nodemask.h>
13 #include <linux/pagemap.h>
14 #include <linux/mempolicy.h>
15 #include <linux/cpuset.h>
16 #include <linux/mutex.h>
19 #include <asm/pgtable.h>
21 #include <linux/hugetlb.h>
24 const unsigned long hugetlb_zero
= 0, hugetlb_infinity
= ~0UL;
25 static unsigned long nr_huge_pages
, free_huge_pages
, resv_huge_pages
;
26 static unsigned long surplus_huge_pages
;
27 static unsigned long nr_overcommit_huge_pages
;
28 unsigned long max_huge_pages
;
29 unsigned long sysctl_overcommit_huge_pages
;
30 static struct list_head hugepage_freelists
[MAX_NUMNODES
];
31 static unsigned int nr_huge_pages_node
[MAX_NUMNODES
];
32 static unsigned int free_huge_pages_node
[MAX_NUMNODES
];
33 static unsigned int surplus_huge_pages_node
[MAX_NUMNODES
];
34 static gfp_t htlb_alloc_mask
= GFP_HIGHUSER
;
35 unsigned long hugepages_treat_as_movable
;
36 static int hugetlb_next_nid
;
39 * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
41 static DEFINE_SPINLOCK(hugetlb_lock
);
43 static void clear_huge_page(struct page
*page
, unsigned long addr
)
48 for (i
= 0; i
< (HPAGE_SIZE
/PAGE_SIZE
); i
++) {
50 clear_user_highpage(page
+ i
, addr
+ i
* PAGE_SIZE
);
54 static void copy_huge_page(struct page
*dst
, struct page
*src
,
55 unsigned long addr
, struct vm_area_struct
*vma
)
60 for (i
= 0; i
< HPAGE_SIZE
/PAGE_SIZE
; i
++) {
62 copy_user_highpage(dst
+ i
, src
+ i
, addr
+ i
*PAGE_SIZE
, vma
);
66 static void enqueue_huge_page(struct page
*page
)
68 int nid
= page_to_nid(page
);
69 list_add(&page
->lru
, &hugepage_freelists
[nid
]);
71 free_huge_pages_node
[nid
]++;
74 static struct page
*dequeue_huge_page(struct vm_area_struct
*vma
,
75 unsigned long address
)
78 struct page
*page
= NULL
;
79 struct mempolicy
*mpol
;
80 struct zonelist
*zonelist
= huge_zonelist(vma
, address
,
81 htlb_alloc_mask
, &mpol
);
84 for (z
= zonelist
->zones
; *z
; z
++) {
85 nid
= zone_to_nid(*z
);
86 if (cpuset_zone_allowed_softwall(*z
, htlb_alloc_mask
) &&
87 !list_empty(&hugepage_freelists
[nid
])) {
88 page
= list_entry(hugepage_freelists
[nid
].next
,
92 free_huge_pages_node
[nid
]--;
93 if (vma
&& vma
->vm_flags
& VM_MAYSHARE
)
98 mpol_free(mpol
); /* unref if mpol !NULL */
102 static void update_and_free_page(struct page
*page
)
106 nr_huge_pages_node
[page_to_nid(page
)]--;
107 for (i
= 0; i
< (HPAGE_SIZE
/ PAGE_SIZE
); i
++) {
108 page
[i
].flags
&= ~(1 << PG_locked
| 1 << PG_error
| 1 << PG_referenced
|
109 1 << PG_dirty
| 1 << PG_active
| 1 << PG_reserved
|
110 1 << PG_private
| 1<< PG_writeback
);
112 set_compound_page_dtor(page
, NULL
);
113 set_page_refcounted(page
);
114 __free_pages(page
, HUGETLB_PAGE_ORDER
);
117 static void free_huge_page(struct page
*page
)
119 int nid
= page_to_nid(page
);
120 struct address_space
*mapping
;
122 mapping
= (struct address_space
*) page_private(page
);
123 set_page_private(page
, 0);
124 BUG_ON(page_count(page
));
125 INIT_LIST_HEAD(&page
->lru
);
127 spin_lock(&hugetlb_lock
);
128 if (surplus_huge_pages_node
[nid
]) {
129 update_and_free_page(page
);
130 surplus_huge_pages
--;
131 surplus_huge_pages_node
[nid
]--;
133 enqueue_huge_page(page
);
135 spin_unlock(&hugetlb_lock
);
137 hugetlb_put_quota(mapping
, 1);
141 * Increment or decrement surplus_huge_pages. Keep node-specific counters
142 * balanced by operating on them in a round-robin fashion.
143 * Returns 1 if an adjustment was made.
145 static int adjust_pool_surplus(int delta
)
151 VM_BUG_ON(delta
!= -1 && delta
!= 1);
153 nid
= next_node(nid
, node_online_map
);
154 if (nid
== MAX_NUMNODES
)
155 nid
= first_node(node_online_map
);
157 /* To shrink on this node, there must be a surplus page */
158 if (delta
< 0 && !surplus_huge_pages_node
[nid
])
160 /* Surplus cannot exceed the total number of pages */
161 if (delta
> 0 && surplus_huge_pages_node
[nid
] >=
162 nr_huge_pages_node
[nid
])
165 surplus_huge_pages
+= delta
;
166 surplus_huge_pages_node
[nid
] += delta
;
169 } while (nid
!= prev_nid
);
175 static struct page
*alloc_fresh_huge_page_node(int nid
)
179 page
= alloc_pages_node(nid
,
180 htlb_alloc_mask
|__GFP_COMP
|__GFP_THISNODE
|__GFP_NOWARN
,
183 set_compound_page_dtor(page
, free_huge_page
);
184 spin_lock(&hugetlb_lock
);
186 nr_huge_pages_node
[nid
]++;
187 spin_unlock(&hugetlb_lock
);
188 put_page(page
); /* free it into the hugepage allocator */
194 static int alloc_fresh_huge_page(void)
201 start_nid
= hugetlb_next_nid
;
204 page
= alloc_fresh_huge_page_node(hugetlb_next_nid
);
208 * Use a helper variable to find the next node and then
209 * copy it back to hugetlb_next_nid afterwards:
210 * otherwise there's a window in which a racer might
211 * pass invalid nid MAX_NUMNODES to alloc_pages_node.
212 * But we don't need to use a spin_lock here: it really
213 * doesn't matter if occasionally a racer chooses the
214 * same nid as we do. Move nid forward in the mask even
215 * if we just successfully allocated a hugepage so that
216 * the next caller gets hugepages on the next node.
218 next_nid
= next_node(hugetlb_next_nid
, node_online_map
);
219 if (next_nid
== MAX_NUMNODES
)
220 next_nid
= first_node(node_online_map
);
221 hugetlb_next_nid
= next_nid
;
222 } while (!page
&& hugetlb_next_nid
!= start_nid
);
227 static struct page
*alloc_buddy_huge_page(struct vm_area_struct
*vma
,
228 unsigned long address
)
234 * Assume we will successfully allocate the surplus page to
235 * prevent racing processes from causing the surplus to exceed
238 * This however introduces a different race, where a process B
239 * tries to grow the static hugepage pool while alloc_pages() is
240 * called by process A. B will only examine the per-node
241 * counters in determining if surplus huge pages can be
242 * converted to normal huge pages in adjust_pool_surplus(). A
243 * won't be able to increment the per-node counter, until the
244 * lock is dropped by B, but B doesn't drop hugetlb_lock until
245 * no more huge pages can be converted from surplus to normal
246 * state (and doesn't try to convert again). Thus, we have a
247 * case where a surplus huge page exists, the pool is grown, and
248 * the surplus huge page still exists after, even though it
249 * should just have been converted to a normal huge page. This
250 * does not leak memory, though, as the hugepage will be freed
251 * once it is out of use. It also does not allow the counters to
252 * go out of whack in adjust_pool_surplus() as we don't modify
253 * the node values until we've gotten the hugepage and only the
254 * per-node value is checked there.
256 spin_lock(&hugetlb_lock
);
257 if (surplus_huge_pages
>= nr_overcommit_huge_pages
) {
258 spin_unlock(&hugetlb_lock
);
262 surplus_huge_pages
++;
264 spin_unlock(&hugetlb_lock
);
266 page
= alloc_pages(htlb_alloc_mask
|__GFP_COMP
|__GFP_NOWARN
,
269 spin_lock(&hugetlb_lock
);
271 nid
= page_to_nid(page
);
272 set_compound_page_dtor(page
, free_huge_page
);
274 * We incremented the global counters already
276 nr_huge_pages_node
[nid
]++;
277 surplus_huge_pages_node
[nid
]++;
280 surplus_huge_pages
--;
282 spin_unlock(&hugetlb_lock
);
288 * Increase the hugetlb pool such that it can accomodate a reservation
291 static int gather_surplus_pages(int delta
)
293 struct list_head surplus_list
;
294 struct page
*page
, *tmp
;
296 int needed
, allocated
;
298 needed
= (resv_huge_pages
+ delta
) - free_huge_pages
;
300 resv_huge_pages
+= delta
;
305 INIT_LIST_HEAD(&surplus_list
);
309 spin_unlock(&hugetlb_lock
);
310 for (i
= 0; i
< needed
; i
++) {
311 page
= alloc_buddy_huge_page(NULL
, 0);
314 * We were not able to allocate enough pages to
315 * satisfy the entire reservation so we free what
316 * we've allocated so far.
318 spin_lock(&hugetlb_lock
);
323 list_add(&page
->lru
, &surplus_list
);
328 * After retaking hugetlb_lock, we need to recalculate 'needed'
329 * because either resv_huge_pages or free_huge_pages may have changed.
331 spin_lock(&hugetlb_lock
);
332 needed
= (resv_huge_pages
+ delta
) - (free_huge_pages
+ allocated
);
337 * The surplus_list now contains _at_least_ the number of extra pages
338 * needed to accomodate the reservation. Add the appropriate number
339 * of pages to the hugetlb pool and free the extras back to the buddy
340 * allocator. Commit the entire reservation here to prevent another
341 * process from stealing the pages as they are added to the pool but
342 * before they are reserved.
345 resv_huge_pages
+= delta
;
348 list_for_each_entry_safe(page
, tmp
, &surplus_list
, lru
) {
349 list_del(&page
->lru
);
351 enqueue_huge_page(page
);
354 * Decrement the refcount and free the page using its
355 * destructor. This must be done with hugetlb_lock
356 * unlocked which is safe because free_huge_page takes
357 * hugetlb_lock before deciding how to free the page.
359 spin_unlock(&hugetlb_lock
);
361 spin_lock(&hugetlb_lock
);
369 * When releasing a hugetlb pool reservation, any surplus pages that were
370 * allocated to satisfy the reservation must be explicitly freed if they were
373 static void return_unused_surplus_pages(unsigned long unused_resv_pages
)
377 unsigned long nr_pages
;
379 /* Uncommit the reservation */
380 resv_huge_pages
-= unused_resv_pages
;
382 nr_pages
= min(unused_resv_pages
, surplus_huge_pages
);
385 nid
= next_node(nid
, node_online_map
);
386 if (nid
== MAX_NUMNODES
)
387 nid
= first_node(node_online_map
);
389 if (!surplus_huge_pages_node
[nid
])
392 if (!list_empty(&hugepage_freelists
[nid
])) {
393 page
= list_entry(hugepage_freelists
[nid
].next
,
395 list_del(&page
->lru
);
396 update_and_free_page(page
);
398 free_huge_pages_node
[nid
]--;
399 surplus_huge_pages
--;
400 surplus_huge_pages_node
[nid
]--;
407 static struct page
*alloc_huge_page_shared(struct vm_area_struct
*vma
,
412 spin_lock(&hugetlb_lock
);
413 page
= dequeue_huge_page(vma
, addr
);
414 spin_unlock(&hugetlb_lock
);
415 return page
? page
: ERR_PTR(-VM_FAULT_OOM
);
418 static struct page
*alloc_huge_page_private(struct vm_area_struct
*vma
,
421 struct page
*page
= NULL
;
423 if (hugetlb_get_quota(vma
->vm_file
->f_mapping
, 1))
424 return ERR_PTR(-VM_FAULT_SIGBUS
);
426 spin_lock(&hugetlb_lock
);
427 if (free_huge_pages
> resv_huge_pages
)
428 page
= dequeue_huge_page(vma
, addr
);
429 spin_unlock(&hugetlb_lock
);
431 page
= alloc_buddy_huge_page(vma
, addr
);
433 hugetlb_put_quota(vma
->vm_file
->f_mapping
, 1);
434 return ERR_PTR(-VM_FAULT_OOM
);
440 static struct page
*alloc_huge_page(struct vm_area_struct
*vma
,
444 struct address_space
*mapping
= vma
->vm_file
->f_mapping
;
446 if (vma
->vm_flags
& VM_MAYSHARE
)
447 page
= alloc_huge_page_shared(vma
, addr
);
449 page
= alloc_huge_page_private(vma
, addr
);
452 set_page_refcounted(page
);
453 set_page_private(page
, (unsigned long) mapping
);
458 static int __init
hugetlb_init(void)
462 if (HPAGE_SHIFT
== 0)
465 for (i
= 0; i
< MAX_NUMNODES
; ++i
)
466 INIT_LIST_HEAD(&hugepage_freelists
[i
]);
468 hugetlb_next_nid
= first_node(node_online_map
);
470 for (i
= 0; i
< max_huge_pages
; ++i
) {
471 if (!alloc_fresh_huge_page())
474 max_huge_pages
= free_huge_pages
= nr_huge_pages
= i
;
475 printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages
);
478 module_init(hugetlb_init
);
480 static int __init
hugetlb_setup(char *s
)
482 if (sscanf(s
, "%lu", &max_huge_pages
) <= 0)
486 __setup("hugepages=", hugetlb_setup
);
488 static unsigned int cpuset_mems_nr(unsigned int *array
)
493 for_each_node_mask(node
, cpuset_current_mems_allowed
)
500 #ifdef CONFIG_HIGHMEM
501 static void try_to_free_low(unsigned long count
)
505 for (i
= 0; i
< MAX_NUMNODES
; ++i
) {
506 struct page
*page
, *next
;
507 list_for_each_entry_safe(page
, next
, &hugepage_freelists
[i
], lru
) {
508 if (count
>= nr_huge_pages
)
510 if (PageHighMem(page
))
512 list_del(&page
->lru
);
513 update_and_free_page(page
);
515 free_huge_pages_node
[page_to_nid(page
)]--;
520 static inline void try_to_free_low(unsigned long count
)
525 #define persistent_huge_pages (nr_huge_pages - surplus_huge_pages)
526 static unsigned long set_max_huge_pages(unsigned long count
)
528 unsigned long min_count
, ret
;
531 * Increase the pool size
532 * First take pages out of surplus state. Then make up the
533 * remaining difference by allocating fresh huge pages.
535 * We might race with alloc_buddy_huge_page() here and be unable
536 * to convert a surplus huge page to a normal huge page. That is
537 * not critical, though, it just means the overall size of the
538 * pool might be one hugepage larger than it needs to be, but
539 * within all the constraints specified by the sysctls.
541 spin_lock(&hugetlb_lock
);
542 while (surplus_huge_pages
&& count
> persistent_huge_pages
) {
543 if (!adjust_pool_surplus(-1))
547 while (count
> persistent_huge_pages
) {
550 * If this allocation races such that we no longer need the
551 * page, free_huge_page will handle it by freeing the page
552 * and reducing the surplus.
554 spin_unlock(&hugetlb_lock
);
555 ret
= alloc_fresh_huge_page();
556 spin_lock(&hugetlb_lock
);
563 * Decrease the pool size
564 * First return free pages to the buddy allocator (being careful
565 * to keep enough around to satisfy reservations). Then place
566 * pages into surplus state as needed so the pool will shrink
567 * to the desired size as pages become free.
569 * By placing pages into the surplus state independent of the
570 * overcommit value, we are allowing the surplus pool size to
571 * exceed overcommit. There are few sane options here. Since
572 * alloc_buddy_huge_page() is checking the global counter,
573 * though, we'll note that we're not allowed to exceed surplus
574 * and won't grow the pool anywhere else. Not until one of the
575 * sysctls are changed, or the surplus pages go out of use.
577 min_count
= resv_huge_pages
+ nr_huge_pages
- free_huge_pages
;
578 min_count
= max(count
, min_count
);
579 try_to_free_low(min_count
);
580 while (min_count
< persistent_huge_pages
) {
581 struct page
*page
= dequeue_huge_page(NULL
, 0);
584 update_and_free_page(page
);
586 while (count
< persistent_huge_pages
) {
587 if (!adjust_pool_surplus(1))
591 ret
= persistent_huge_pages
;
592 spin_unlock(&hugetlb_lock
);
596 int hugetlb_sysctl_handler(struct ctl_table
*table
, int write
,
597 struct file
*file
, void __user
*buffer
,
598 size_t *length
, loff_t
*ppos
)
600 proc_doulongvec_minmax(table
, write
, file
, buffer
, length
, ppos
);
601 max_huge_pages
= set_max_huge_pages(max_huge_pages
);
605 int hugetlb_treat_movable_handler(struct ctl_table
*table
, int write
,
606 struct file
*file
, void __user
*buffer
,
607 size_t *length
, loff_t
*ppos
)
609 proc_dointvec(table
, write
, file
, buffer
, length
, ppos
);
610 if (hugepages_treat_as_movable
)
611 htlb_alloc_mask
= GFP_HIGHUSER_MOVABLE
;
613 htlb_alloc_mask
= GFP_HIGHUSER
;
617 int hugetlb_overcommit_handler(struct ctl_table
*table
, int write
,
618 struct file
*file
, void __user
*buffer
,
619 size_t *length
, loff_t
*ppos
)
621 proc_doulongvec_minmax(table
, write
, file
, buffer
, length
, ppos
);
622 spin_lock(&hugetlb_lock
);
623 nr_overcommit_huge_pages
= sysctl_overcommit_huge_pages
;
624 spin_unlock(&hugetlb_lock
);
628 #endif /* CONFIG_SYSCTL */
630 int hugetlb_report_meminfo(char *buf
)
633 "HugePages_Total: %5lu\n"
634 "HugePages_Free: %5lu\n"
635 "HugePages_Rsvd: %5lu\n"
636 "HugePages_Surp: %5lu\n"
637 "Hugepagesize: %5lu kB\n",
645 int hugetlb_report_node_meminfo(int nid
, char *buf
)
648 "Node %d HugePages_Total: %5u\n"
649 "Node %d HugePages_Free: %5u\n",
650 nid
, nr_huge_pages_node
[nid
],
651 nid
, free_huge_pages_node
[nid
]);
654 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
655 unsigned long hugetlb_total_pages(void)
657 return nr_huge_pages
* (HPAGE_SIZE
/ PAGE_SIZE
);
661 * We cannot handle pagefaults against hugetlb pages at all. They cause
662 * handle_mm_fault() to try to instantiate regular-sized pages in the
663 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
666 static int hugetlb_vm_op_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
672 struct vm_operations_struct hugetlb_vm_ops
= {
673 .fault
= hugetlb_vm_op_fault
,
676 static pte_t
make_huge_pte(struct vm_area_struct
*vma
, struct page
*page
,
683 pte_mkwrite(pte_mkdirty(mk_pte(page
, vma
->vm_page_prot
)));
685 entry
= pte_wrprotect(mk_pte(page
, vma
->vm_page_prot
));
687 entry
= pte_mkyoung(entry
);
688 entry
= pte_mkhuge(entry
);
693 static void set_huge_ptep_writable(struct vm_area_struct
*vma
,
694 unsigned long address
, pte_t
*ptep
)
698 entry
= pte_mkwrite(pte_mkdirty(*ptep
));
699 if (ptep_set_access_flags(vma
, address
, ptep
, entry
, 1)) {
700 update_mmu_cache(vma
, address
, entry
);
705 int copy_hugetlb_page_range(struct mm_struct
*dst
, struct mm_struct
*src
,
706 struct vm_area_struct
*vma
)
708 pte_t
*src_pte
, *dst_pte
, entry
;
709 struct page
*ptepage
;
713 cow
= (vma
->vm_flags
& (VM_SHARED
| VM_MAYWRITE
)) == VM_MAYWRITE
;
715 for (addr
= vma
->vm_start
; addr
< vma
->vm_end
; addr
+= HPAGE_SIZE
) {
716 src_pte
= huge_pte_offset(src
, addr
);
719 dst_pte
= huge_pte_alloc(dst
, addr
);
723 /* If the pagetables are shared don't copy or take references */
724 if (dst_pte
== src_pte
)
727 spin_lock(&dst
->page_table_lock
);
728 spin_lock(&src
->page_table_lock
);
729 if (!pte_none(*src_pte
)) {
731 ptep_set_wrprotect(src
, addr
, src_pte
);
733 ptepage
= pte_page(entry
);
735 set_huge_pte_at(dst
, addr
, dst_pte
, entry
);
737 spin_unlock(&src
->page_table_lock
);
738 spin_unlock(&dst
->page_table_lock
);
746 void __unmap_hugepage_range(struct vm_area_struct
*vma
, unsigned long start
,
749 struct mm_struct
*mm
= vma
->vm_mm
;
750 unsigned long address
;
756 * A page gathering list, protected by per file i_mmap_lock. The
757 * lock is used to avoid list corruption from multiple unmapping
758 * of the same page since we are using page->lru.
760 LIST_HEAD(page_list
);
762 WARN_ON(!is_vm_hugetlb_page(vma
));
763 BUG_ON(start
& ~HPAGE_MASK
);
764 BUG_ON(end
& ~HPAGE_MASK
);
766 spin_lock(&mm
->page_table_lock
);
767 for (address
= start
; address
< end
; address
+= HPAGE_SIZE
) {
768 ptep
= huge_pte_offset(mm
, address
);
772 if (huge_pmd_unshare(mm
, &address
, ptep
))
775 pte
= huge_ptep_get_and_clear(mm
, address
, ptep
);
779 page
= pte_page(pte
);
781 set_page_dirty(page
);
782 list_add(&page
->lru
, &page_list
);
784 spin_unlock(&mm
->page_table_lock
);
785 flush_tlb_range(vma
, start
, end
);
786 list_for_each_entry_safe(page
, tmp
, &page_list
, lru
) {
787 list_del(&page
->lru
);
792 void unmap_hugepage_range(struct vm_area_struct
*vma
, unsigned long start
,
796 * It is undesirable to test vma->vm_file as it should be non-null
797 * for valid hugetlb area. However, vm_file will be NULL in the error
798 * cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails,
799 * do_mmap_pgoff() nullifies vma->vm_file before calling this function
800 * to clean up. Since no pte has actually been setup, it is safe to
801 * do nothing in this case.
804 spin_lock(&vma
->vm_file
->f_mapping
->i_mmap_lock
);
805 __unmap_hugepage_range(vma
, start
, end
);
806 spin_unlock(&vma
->vm_file
->f_mapping
->i_mmap_lock
);
810 static int hugetlb_cow(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
811 unsigned long address
, pte_t
*ptep
, pte_t pte
)
813 struct page
*old_page
, *new_page
;
816 old_page
= pte_page(pte
);
818 /* If no-one else is actually using this page, avoid the copy
819 * and just make the page writable */
820 avoidcopy
= (page_count(old_page
) == 1);
822 set_huge_ptep_writable(vma
, address
, ptep
);
826 page_cache_get(old_page
);
827 new_page
= alloc_huge_page(vma
, address
);
829 if (IS_ERR(new_page
)) {
830 page_cache_release(old_page
);
831 return -PTR_ERR(new_page
);
834 spin_unlock(&mm
->page_table_lock
);
835 copy_huge_page(new_page
, old_page
, address
, vma
);
836 __SetPageUptodate(new_page
);
837 spin_lock(&mm
->page_table_lock
);
839 ptep
= huge_pte_offset(mm
, address
& HPAGE_MASK
);
840 if (likely(pte_same(*ptep
, pte
))) {
842 set_huge_pte_at(mm
, address
, ptep
,
843 make_huge_pte(vma
, new_page
, 1));
844 /* Make the old page be freed below */
847 page_cache_release(new_page
);
848 page_cache_release(old_page
);
852 static int hugetlb_no_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
853 unsigned long address
, pte_t
*ptep
, int write_access
)
855 int ret
= VM_FAULT_SIGBUS
;
859 struct address_space
*mapping
;
862 mapping
= vma
->vm_file
->f_mapping
;
863 idx
= ((address
- vma
->vm_start
) >> HPAGE_SHIFT
)
864 + (vma
->vm_pgoff
>> (HPAGE_SHIFT
- PAGE_SHIFT
));
867 * Use page lock to guard against racing truncation
868 * before we get page_table_lock.
871 page
= find_lock_page(mapping
, idx
);
873 size
= i_size_read(mapping
->host
) >> HPAGE_SHIFT
;
876 page
= alloc_huge_page(vma
, address
);
878 ret
= -PTR_ERR(page
);
881 clear_huge_page(page
, address
);
882 __SetPageUptodate(page
);
884 if (vma
->vm_flags
& VM_SHARED
) {
886 struct inode
*inode
= mapping
->host
;
888 err
= add_to_page_cache(page
, mapping
, idx
, GFP_KERNEL
);
896 spin_lock(&inode
->i_lock
);
897 inode
->i_blocks
+= BLOCKS_PER_HUGEPAGE
;
898 spin_unlock(&inode
->i_lock
);
903 spin_lock(&mm
->page_table_lock
);
904 size
= i_size_read(mapping
->host
) >> HPAGE_SHIFT
;
909 if (!pte_none(*ptep
))
912 new_pte
= make_huge_pte(vma
, page
, ((vma
->vm_flags
& VM_WRITE
)
913 && (vma
->vm_flags
& VM_SHARED
)));
914 set_huge_pte_at(mm
, address
, ptep
, new_pte
);
916 if (write_access
&& !(vma
->vm_flags
& VM_SHARED
)) {
917 /* Optimization, do the COW without a second fault */
918 ret
= hugetlb_cow(mm
, vma
, address
, ptep
, new_pte
);
921 spin_unlock(&mm
->page_table_lock
);
927 spin_unlock(&mm
->page_table_lock
);
933 int hugetlb_fault(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
934 unsigned long address
, int write_access
)
939 static DEFINE_MUTEX(hugetlb_instantiation_mutex
);
941 ptep
= huge_pte_alloc(mm
, address
);
946 * Serialize hugepage allocation and instantiation, so that we don't
947 * get spurious allocation failures if two CPUs race to instantiate
948 * the same page in the page cache.
950 mutex_lock(&hugetlb_instantiation_mutex
);
952 if (pte_none(entry
)) {
953 ret
= hugetlb_no_page(mm
, vma
, address
, ptep
, write_access
);
954 mutex_unlock(&hugetlb_instantiation_mutex
);
960 spin_lock(&mm
->page_table_lock
);
961 /* Check for a racing update before calling hugetlb_cow */
962 if (likely(pte_same(entry
, *ptep
)))
963 if (write_access
&& !pte_write(entry
))
964 ret
= hugetlb_cow(mm
, vma
, address
, ptep
, entry
);
965 spin_unlock(&mm
->page_table_lock
);
966 mutex_unlock(&hugetlb_instantiation_mutex
);
971 int follow_hugetlb_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
972 struct page
**pages
, struct vm_area_struct
**vmas
,
973 unsigned long *position
, int *length
, int i
,
976 unsigned long pfn_offset
;
977 unsigned long vaddr
= *position
;
978 int remainder
= *length
;
980 spin_lock(&mm
->page_table_lock
);
981 while (vaddr
< vma
->vm_end
&& remainder
) {
986 * Some archs (sparc64, sh*) have multiple pte_ts to
987 * each hugepage. We have to make * sure we get the
988 * first, for the page indexing below to work.
990 pte
= huge_pte_offset(mm
, vaddr
& HPAGE_MASK
);
992 if (!pte
|| pte_none(*pte
) || (write
&& !pte_write(*pte
))) {
995 spin_unlock(&mm
->page_table_lock
);
996 ret
= hugetlb_fault(mm
, vma
, vaddr
, write
);
997 spin_lock(&mm
->page_table_lock
);
998 if (!(ret
& VM_FAULT_ERROR
))
1007 pfn_offset
= (vaddr
& ~HPAGE_MASK
) >> PAGE_SHIFT
;
1008 page
= pte_page(*pte
);
1012 pages
[i
] = page
+ pfn_offset
;
1022 if (vaddr
< vma
->vm_end
&& remainder
&&
1023 pfn_offset
< HPAGE_SIZE
/PAGE_SIZE
) {
1025 * We use pfn_offset to avoid touching the pageframes
1026 * of this compound page.
1031 spin_unlock(&mm
->page_table_lock
);
1032 *length
= remainder
;
1038 void hugetlb_change_protection(struct vm_area_struct
*vma
,
1039 unsigned long address
, unsigned long end
, pgprot_t newprot
)
1041 struct mm_struct
*mm
= vma
->vm_mm
;
1042 unsigned long start
= address
;
1046 BUG_ON(address
>= end
);
1047 flush_cache_range(vma
, address
, end
);
1049 spin_lock(&vma
->vm_file
->f_mapping
->i_mmap_lock
);
1050 spin_lock(&mm
->page_table_lock
);
1051 for (; address
< end
; address
+= HPAGE_SIZE
) {
1052 ptep
= huge_pte_offset(mm
, address
);
1055 if (huge_pmd_unshare(mm
, &address
, ptep
))
1057 if (!pte_none(*ptep
)) {
1058 pte
= huge_ptep_get_and_clear(mm
, address
, ptep
);
1059 pte
= pte_mkhuge(pte_modify(pte
, newprot
));
1060 set_huge_pte_at(mm
, address
, ptep
, pte
);
1063 spin_unlock(&mm
->page_table_lock
);
1064 spin_unlock(&vma
->vm_file
->f_mapping
->i_mmap_lock
);
1066 flush_tlb_range(vma
, start
, end
);
1069 struct file_region
{
1070 struct list_head link
;
1075 static long region_add(struct list_head
*head
, long f
, long t
)
1077 struct file_region
*rg
, *nrg
, *trg
;
1079 /* Locate the region we are either in or before. */
1080 list_for_each_entry(rg
, head
, link
)
1084 /* Round our left edge to the current segment if it encloses us. */
1088 /* Check for and consume any regions we now overlap with. */
1090 list_for_each_entry_safe(rg
, trg
, rg
->link
.prev
, link
) {
1091 if (&rg
->link
== head
)
1096 /* If this area reaches higher then extend our area to
1097 * include it completely. If this is not the first area
1098 * which we intend to reuse, free it. */
1102 list_del(&rg
->link
);
1111 static long region_chg(struct list_head
*head
, long f
, long t
)
1113 struct file_region
*rg
, *nrg
;
1116 /* Locate the region we are before or in. */
1117 list_for_each_entry(rg
, head
, link
)
1121 /* If we are below the current region then a new region is required.
1122 * Subtle, allocate a new region at the position but make it zero
1123 * size such that we can guarantee to record the reservation. */
1124 if (&rg
->link
== head
|| t
< rg
->from
) {
1125 nrg
= kmalloc(sizeof(*nrg
), GFP_KERNEL
);
1130 INIT_LIST_HEAD(&nrg
->link
);
1131 list_add(&nrg
->link
, rg
->link
.prev
);
1136 /* Round our left edge to the current segment if it encloses us. */
1141 /* Check for and consume any regions we now overlap with. */
1142 list_for_each_entry(rg
, rg
->link
.prev
, link
) {
1143 if (&rg
->link
== head
)
1148 /* We overlap with this area, if it extends futher than
1149 * us then we must extend ourselves. Account for its
1150 * existing reservation. */
1155 chg
-= rg
->to
- rg
->from
;
1160 static long region_truncate(struct list_head
*head
, long end
)
1162 struct file_region
*rg
, *trg
;
1165 /* Locate the region we are either in or before. */
1166 list_for_each_entry(rg
, head
, link
)
1169 if (&rg
->link
== head
)
1172 /* If we are in the middle of a region then adjust it. */
1173 if (end
> rg
->from
) {
1176 rg
= list_entry(rg
->link
.next
, typeof(*rg
), link
);
1179 /* Drop any remaining regions. */
1180 list_for_each_entry_safe(rg
, trg
, rg
->link
.prev
, link
) {
1181 if (&rg
->link
== head
)
1183 chg
+= rg
->to
- rg
->from
;
1184 list_del(&rg
->link
);
1190 static int hugetlb_acct_memory(long delta
)
1194 spin_lock(&hugetlb_lock
);
1196 * When cpuset is configured, it breaks the strict hugetlb page
1197 * reservation as the accounting is done on a global variable. Such
1198 * reservation is completely rubbish in the presence of cpuset because
1199 * the reservation is not checked against page availability for the
1200 * current cpuset. Application can still potentially OOM'ed by kernel
1201 * with lack of free htlb page in cpuset that the task is in.
1202 * Attempt to enforce strict accounting with cpuset is almost
1203 * impossible (or too ugly) because cpuset is too fluid that
1204 * task or memory node can be dynamically moved between cpusets.
1206 * The change of semantics for shared hugetlb mapping with cpuset is
1207 * undesirable. However, in order to preserve some of the semantics,
1208 * we fall back to check against current free page availability as
1209 * a best attempt and hopefully to minimize the impact of changing
1210 * semantics that cpuset has.
1213 if (gather_surplus_pages(delta
) < 0)
1216 if (delta
> cpuset_mems_nr(free_huge_pages_node
)) {
1217 return_unused_surplus_pages(delta
);
1224 return_unused_surplus_pages((unsigned long) -delta
);
1227 spin_unlock(&hugetlb_lock
);
1231 int hugetlb_reserve_pages(struct inode
*inode
, long from
, long to
)
1235 chg
= region_chg(&inode
->i_mapping
->private_list
, from
, to
);
1239 if (hugetlb_get_quota(inode
->i_mapping
, chg
))
1241 ret
= hugetlb_acct_memory(chg
);
1243 hugetlb_put_quota(inode
->i_mapping
, chg
);
1246 region_add(&inode
->i_mapping
->private_list
, from
, to
);
1250 void hugetlb_unreserve_pages(struct inode
*inode
, long offset
, long freed
)
1252 long chg
= region_truncate(&inode
->i_mapping
->private_list
, offset
);
1254 spin_lock(&inode
->i_lock
);
1255 inode
->i_blocks
-= BLOCKS_PER_HUGEPAGE
* freed
;
1256 spin_unlock(&inode
->i_lock
);
1258 hugetlb_put_quota(inode
->i_mapping
, (chg
- freed
));
1259 hugetlb_acct_memory(-(chg
- freed
));