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(void)
77 struct page
*page
= NULL
;
79 for (nid
= 0; nid
< MAX_NUMNODES
; ++nid
) {
80 if (!list_empty(&hugepage_freelists
[nid
])) {
81 page
= list_entry(hugepage_freelists
[nid
].next
,
85 free_huge_pages_node
[nid
]--;
92 static struct page
*dequeue_huge_page_vma(struct vm_area_struct
*vma
,
93 unsigned long address
)
96 struct page
*page
= NULL
;
97 struct mempolicy
*mpol
;
99 struct zonelist
*zonelist
= huge_zonelist(vma
, address
,
100 htlb_alloc_mask
, &mpol
, &nodemask
);
104 for_each_zone_zonelist_nodemask(zone
, z
, zonelist
,
105 MAX_NR_ZONES
- 1, nodemask
) {
106 nid
= zone_to_nid(zone
);
107 if (cpuset_zone_allowed_softwall(zone
, htlb_alloc_mask
) &&
108 !list_empty(&hugepage_freelists
[nid
])) {
109 page
= list_entry(hugepage_freelists
[nid
].next
,
111 list_del(&page
->lru
);
113 free_huge_pages_node
[nid
]--;
114 if (vma
&& vma
->vm_flags
& VM_MAYSHARE
)
119 mpol_free(mpol
); /* unref if mpol !NULL */
123 static void update_and_free_page(struct page
*page
)
127 nr_huge_pages_node
[page_to_nid(page
)]--;
128 for (i
= 0; i
< (HPAGE_SIZE
/ PAGE_SIZE
); i
++) {
129 page
[i
].flags
&= ~(1 << PG_locked
| 1 << PG_error
| 1 << PG_referenced
|
130 1 << PG_dirty
| 1 << PG_active
| 1 << PG_reserved
|
131 1 << PG_private
| 1<< PG_writeback
);
133 set_compound_page_dtor(page
, NULL
);
134 set_page_refcounted(page
);
135 __free_pages(page
, HUGETLB_PAGE_ORDER
);
138 static void free_huge_page(struct page
*page
)
140 int nid
= page_to_nid(page
);
141 struct address_space
*mapping
;
143 mapping
= (struct address_space
*) page_private(page
);
144 set_page_private(page
, 0);
145 BUG_ON(page_count(page
));
146 INIT_LIST_HEAD(&page
->lru
);
148 spin_lock(&hugetlb_lock
);
149 if (surplus_huge_pages_node
[nid
]) {
150 update_and_free_page(page
);
151 surplus_huge_pages
--;
152 surplus_huge_pages_node
[nid
]--;
154 enqueue_huge_page(page
);
156 spin_unlock(&hugetlb_lock
);
158 hugetlb_put_quota(mapping
, 1);
162 * Increment or decrement surplus_huge_pages. Keep node-specific counters
163 * balanced by operating on them in a round-robin fashion.
164 * Returns 1 if an adjustment was made.
166 static int adjust_pool_surplus(int delta
)
172 VM_BUG_ON(delta
!= -1 && delta
!= 1);
174 nid
= next_node(nid
, node_online_map
);
175 if (nid
== MAX_NUMNODES
)
176 nid
= first_node(node_online_map
);
178 /* To shrink on this node, there must be a surplus page */
179 if (delta
< 0 && !surplus_huge_pages_node
[nid
])
181 /* Surplus cannot exceed the total number of pages */
182 if (delta
> 0 && surplus_huge_pages_node
[nid
] >=
183 nr_huge_pages_node
[nid
])
186 surplus_huge_pages
+= delta
;
187 surplus_huge_pages_node
[nid
] += delta
;
190 } while (nid
!= prev_nid
);
196 static struct page
*alloc_fresh_huge_page_node(int nid
)
200 page
= alloc_pages_node(nid
,
201 htlb_alloc_mask
|__GFP_COMP
|__GFP_THISNODE
|__GFP_NOWARN
,
204 set_compound_page_dtor(page
, free_huge_page
);
205 spin_lock(&hugetlb_lock
);
207 nr_huge_pages_node
[nid
]++;
208 spin_unlock(&hugetlb_lock
);
209 put_page(page
); /* free it into the hugepage allocator */
215 static int alloc_fresh_huge_page(void)
222 start_nid
= hugetlb_next_nid
;
225 page
= alloc_fresh_huge_page_node(hugetlb_next_nid
);
229 * Use a helper variable to find the next node and then
230 * copy it back to hugetlb_next_nid afterwards:
231 * otherwise there's a window in which a racer might
232 * pass invalid nid MAX_NUMNODES to alloc_pages_node.
233 * But we don't need to use a spin_lock here: it really
234 * doesn't matter if occasionally a racer chooses the
235 * same nid as we do. Move nid forward in the mask even
236 * if we just successfully allocated a hugepage so that
237 * the next caller gets hugepages on the next node.
239 next_nid
= next_node(hugetlb_next_nid
, node_online_map
);
240 if (next_nid
== MAX_NUMNODES
)
241 next_nid
= first_node(node_online_map
);
242 hugetlb_next_nid
= next_nid
;
243 } while (!page
&& hugetlb_next_nid
!= start_nid
);
248 static struct page
*alloc_buddy_huge_page(struct vm_area_struct
*vma
,
249 unsigned long address
)
255 * Assume we will successfully allocate the surplus page to
256 * prevent racing processes from causing the surplus to exceed
259 * This however introduces a different race, where a process B
260 * tries to grow the static hugepage pool while alloc_pages() is
261 * called by process A. B will only examine the per-node
262 * counters in determining if surplus huge pages can be
263 * converted to normal huge pages in adjust_pool_surplus(). A
264 * won't be able to increment the per-node counter, until the
265 * lock is dropped by B, but B doesn't drop hugetlb_lock until
266 * no more huge pages can be converted from surplus to normal
267 * state (and doesn't try to convert again). Thus, we have a
268 * case where a surplus huge page exists, the pool is grown, and
269 * the surplus huge page still exists after, even though it
270 * should just have been converted to a normal huge page. This
271 * does not leak memory, though, as the hugepage will be freed
272 * once it is out of use. It also does not allow the counters to
273 * go out of whack in adjust_pool_surplus() as we don't modify
274 * the node values until we've gotten the hugepage and only the
275 * per-node value is checked there.
277 spin_lock(&hugetlb_lock
);
278 if (surplus_huge_pages
>= nr_overcommit_huge_pages
) {
279 spin_unlock(&hugetlb_lock
);
283 surplus_huge_pages
++;
285 spin_unlock(&hugetlb_lock
);
287 page
= alloc_pages(htlb_alloc_mask
|__GFP_COMP
|__GFP_NOWARN
,
290 spin_lock(&hugetlb_lock
);
293 * This page is now managed by the hugetlb allocator and has
294 * no users -- drop the buddy allocator's reference.
296 put_page_testzero(page
);
297 VM_BUG_ON(page_count(page
));
298 nid
= page_to_nid(page
);
299 set_compound_page_dtor(page
, free_huge_page
);
301 * We incremented the global counters already
303 nr_huge_pages_node
[nid
]++;
304 surplus_huge_pages_node
[nid
]++;
307 surplus_huge_pages
--;
309 spin_unlock(&hugetlb_lock
);
315 * Increase the hugetlb pool such that it can accomodate a reservation
318 static int gather_surplus_pages(int delta
)
320 struct list_head surplus_list
;
321 struct page
*page
, *tmp
;
323 int needed
, allocated
;
325 needed
= (resv_huge_pages
+ delta
) - free_huge_pages
;
327 resv_huge_pages
+= delta
;
332 INIT_LIST_HEAD(&surplus_list
);
336 spin_unlock(&hugetlb_lock
);
337 for (i
= 0; i
< needed
; i
++) {
338 page
= alloc_buddy_huge_page(NULL
, 0);
341 * We were not able to allocate enough pages to
342 * satisfy the entire reservation so we free what
343 * we've allocated so far.
345 spin_lock(&hugetlb_lock
);
350 list_add(&page
->lru
, &surplus_list
);
355 * After retaking hugetlb_lock, we need to recalculate 'needed'
356 * because either resv_huge_pages or free_huge_pages may have changed.
358 spin_lock(&hugetlb_lock
);
359 needed
= (resv_huge_pages
+ delta
) - (free_huge_pages
+ allocated
);
364 * The surplus_list now contains _at_least_ the number of extra pages
365 * needed to accomodate the reservation. Add the appropriate number
366 * of pages to the hugetlb pool and free the extras back to the buddy
367 * allocator. Commit the entire reservation here to prevent another
368 * process from stealing the pages as they are added to the pool but
369 * before they are reserved.
372 resv_huge_pages
+= delta
;
375 /* Free the needed pages to the hugetlb pool */
376 list_for_each_entry_safe(page
, tmp
, &surplus_list
, lru
) {
379 list_del(&page
->lru
);
380 enqueue_huge_page(page
);
383 /* Free unnecessary surplus pages to the buddy allocator */
384 if (!list_empty(&surplus_list
)) {
385 spin_unlock(&hugetlb_lock
);
386 list_for_each_entry_safe(page
, tmp
, &surplus_list
, lru
) {
387 list_del(&page
->lru
);
389 * The page has a reference count of zero already, so
390 * call free_huge_page directly instead of using
391 * put_page. This must be done with hugetlb_lock
392 * unlocked which is safe because free_huge_page takes
393 * hugetlb_lock before deciding how to free the page.
395 free_huge_page(page
);
397 spin_lock(&hugetlb_lock
);
404 * When releasing a hugetlb pool reservation, any surplus pages that were
405 * allocated to satisfy the reservation must be explicitly freed if they were
408 static void return_unused_surplus_pages(unsigned long unused_resv_pages
)
412 unsigned long nr_pages
;
415 * We want to release as many surplus pages as possible, spread
416 * evenly across all nodes. Iterate across all nodes until we
417 * can no longer free unreserved surplus pages. This occurs when
418 * the nodes with surplus pages have no free pages.
420 unsigned long remaining_iterations
= num_online_nodes();
422 /* Uncommit the reservation */
423 resv_huge_pages
-= unused_resv_pages
;
425 nr_pages
= min(unused_resv_pages
, surplus_huge_pages
);
427 while (remaining_iterations
-- && nr_pages
) {
428 nid
= next_node(nid
, node_online_map
);
429 if (nid
== MAX_NUMNODES
)
430 nid
= first_node(node_online_map
);
432 if (!surplus_huge_pages_node
[nid
])
435 if (!list_empty(&hugepage_freelists
[nid
])) {
436 page
= list_entry(hugepage_freelists
[nid
].next
,
438 list_del(&page
->lru
);
439 update_and_free_page(page
);
441 free_huge_pages_node
[nid
]--;
442 surplus_huge_pages
--;
443 surplus_huge_pages_node
[nid
]--;
445 remaining_iterations
= num_online_nodes();
451 static struct page
*alloc_huge_page_shared(struct vm_area_struct
*vma
,
456 spin_lock(&hugetlb_lock
);
457 page
= dequeue_huge_page_vma(vma
, addr
);
458 spin_unlock(&hugetlb_lock
);
459 return page
? page
: ERR_PTR(-VM_FAULT_OOM
);
462 static struct page
*alloc_huge_page_private(struct vm_area_struct
*vma
,
465 struct page
*page
= NULL
;
467 if (hugetlb_get_quota(vma
->vm_file
->f_mapping
, 1))
468 return ERR_PTR(-VM_FAULT_SIGBUS
);
470 spin_lock(&hugetlb_lock
);
471 if (free_huge_pages
> resv_huge_pages
)
472 page
= dequeue_huge_page_vma(vma
, addr
);
473 spin_unlock(&hugetlb_lock
);
475 page
= alloc_buddy_huge_page(vma
, addr
);
477 hugetlb_put_quota(vma
->vm_file
->f_mapping
, 1);
478 return ERR_PTR(-VM_FAULT_OOM
);
484 static struct page
*alloc_huge_page(struct vm_area_struct
*vma
,
488 struct address_space
*mapping
= vma
->vm_file
->f_mapping
;
490 if (vma
->vm_flags
& VM_MAYSHARE
)
491 page
= alloc_huge_page_shared(vma
, addr
);
493 page
= alloc_huge_page_private(vma
, addr
);
496 set_page_refcounted(page
);
497 set_page_private(page
, (unsigned long) mapping
);
502 static int __init
hugetlb_init(void)
506 if (HPAGE_SHIFT
== 0)
509 for (i
= 0; i
< MAX_NUMNODES
; ++i
)
510 INIT_LIST_HEAD(&hugepage_freelists
[i
]);
512 hugetlb_next_nid
= first_node(node_online_map
);
514 for (i
= 0; i
< max_huge_pages
; ++i
) {
515 if (!alloc_fresh_huge_page())
518 max_huge_pages
= free_huge_pages
= nr_huge_pages
= i
;
519 printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages
);
522 module_init(hugetlb_init
);
524 static int __init
hugetlb_setup(char *s
)
526 if (sscanf(s
, "%lu", &max_huge_pages
) <= 0)
530 __setup("hugepages=", hugetlb_setup
);
532 static unsigned int cpuset_mems_nr(unsigned int *array
)
537 for_each_node_mask(node
, cpuset_current_mems_allowed
)
544 #ifdef CONFIG_HIGHMEM
545 static void try_to_free_low(unsigned long count
)
549 for (i
= 0; i
< MAX_NUMNODES
; ++i
) {
550 struct page
*page
, *next
;
551 list_for_each_entry_safe(page
, next
, &hugepage_freelists
[i
], lru
) {
552 if (count
>= nr_huge_pages
)
554 if (PageHighMem(page
))
556 list_del(&page
->lru
);
557 update_and_free_page(page
);
559 free_huge_pages_node
[page_to_nid(page
)]--;
564 static inline void try_to_free_low(unsigned long count
)
569 #define persistent_huge_pages (nr_huge_pages - surplus_huge_pages)
570 static unsigned long set_max_huge_pages(unsigned long count
)
572 unsigned long min_count
, ret
;
575 * Increase the pool size
576 * First take pages out of surplus state. Then make up the
577 * remaining difference by allocating fresh huge pages.
579 * We might race with alloc_buddy_huge_page() here and be unable
580 * to convert a surplus huge page to a normal huge page. That is
581 * not critical, though, it just means the overall size of the
582 * pool might be one hugepage larger than it needs to be, but
583 * within all the constraints specified by the sysctls.
585 spin_lock(&hugetlb_lock
);
586 while (surplus_huge_pages
&& count
> persistent_huge_pages
) {
587 if (!adjust_pool_surplus(-1))
591 while (count
> persistent_huge_pages
) {
594 * If this allocation races such that we no longer need the
595 * page, free_huge_page will handle it by freeing the page
596 * and reducing the surplus.
598 spin_unlock(&hugetlb_lock
);
599 ret
= alloc_fresh_huge_page();
600 spin_lock(&hugetlb_lock
);
607 * Decrease the pool size
608 * First return free pages to the buddy allocator (being careful
609 * to keep enough around to satisfy reservations). Then place
610 * pages into surplus state as needed so the pool will shrink
611 * to the desired size as pages become free.
613 * By placing pages into the surplus state independent of the
614 * overcommit value, we are allowing the surplus pool size to
615 * exceed overcommit. There are few sane options here. Since
616 * alloc_buddy_huge_page() is checking the global counter,
617 * though, we'll note that we're not allowed to exceed surplus
618 * and won't grow the pool anywhere else. Not until one of the
619 * sysctls are changed, or the surplus pages go out of use.
621 min_count
= resv_huge_pages
+ nr_huge_pages
- free_huge_pages
;
622 min_count
= max(count
, min_count
);
623 try_to_free_low(min_count
);
624 while (min_count
< persistent_huge_pages
) {
625 struct page
*page
= dequeue_huge_page();
628 update_and_free_page(page
);
630 while (count
< persistent_huge_pages
) {
631 if (!adjust_pool_surplus(1))
635 ret
= persistent_huge_pages
;
636 spin_unlock(&hugetlb_lock
);
640 int hugetlb_sysctl_handler(struct ctl_table
*table
, int write
,
641 struct file
*file
, void __user
*buffer
,
642 size_t *length
, loff_t
*ppos
)
644 proc_doulongvec_minmax(table
, write
, file
, buffer
, length
, ppos
);
645 max_huge_pages
= set_max_huge_pages(max_huge_pages
);
649 int hugetlb_treat_movable_handler(struct ctl_table
*table
, int write
,
650 struct file
*file
, void __user
*buffer
,
651 size_t *length
, loff_t
*ppos
)
653 proc_dointvec(table
, write
, file
, buffer
, length
, ppos
);
654 if (hugepages_treat_as_movable
)
655 htlb_alloc_mask
= GFP_HIGHUSER_MOVABLE
;
657 htlb_alloc_mask
= GFP_HIGHUSER
;
661 int hugetlb_overcommit_handler(struct ctl_table
*table
, int write
,
662 struct file
*file
, void __user
*buffer
,
663 size_t *length
, loff_t
*ppos
)
665 proc_doulongvec_minmax(table
, write
, file
, buffer
, length
, ppos
);
666 spin_lock(&hugetlb_lock
);
667 nr_overcommit_huge_pages
= sysctl_overcommit_huge_pages
;
668 spin_unlock(&hugetlb_lock
);
672 #endif /* CONFIG_SYSCTL */
674 int hugetlb_report_meminfo(char *buf
)
677 "HugePages_Total: %5lu\n"
678 "HugePages_Free: %5lu\n"
679 "HugePages_Rsvd: %5lu\n"
680 "HugePages_Surp: %5lu\n"
681 "Hugepagesize: %5lu kB\n",
689 int hugetlb_report_node_meminfo(int nid
, char *buf
)
692 "Node %d HugePages_Total: %5u\n"
693 "Node %d HugePages_Free: %5u\n"
694 "Node %d HugePages_Surp: %5u\n",
695 nid
, nr_huge_pages_node
[nid
],
696 nid
, free_huge_pages_node
[nid
],
697 nid
, surplus_huge_pages_node
[nid
]);
700 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
701 unsigned long hugetlb_total_pages(void)
703 return nr_huge_pages
* (HPAGE_SIZE
/ PAGE_SIZE
);
707 * We cannot handle pagefaults against hugetlb pages at all. They cause
708 * handle_mm_fault() to try to instantiate regular-sized pages in the
709 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
712 static int hugetlb_vm_op_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
718 struct vm_operations_struct hugetlb_vm_ops
= {
719 .fault
= hugetlb_vm_op_fault
,
722 static pte_t
make_huge_pte(struct vm_area_struct
*vma
, struct page
*page
,
729 pte_mkwrite(pte_mkdirty(mk_pte(page
, vma
->vm_page_prot
)));
731 entry
= pte_wrprotect(mk_pte(page
, vma
->vm_page_prot
));
733 entry
= pte_mkyoung(entry
);
734 entry
= pte_mkhuge(entry
);
739 static void set_huge_ptep_writable(struct vm_area_struct
*vma
,
740 unsigned long address
, pte_t
*ptep
)
744 entry
= pte_mkwrite(pte_mkdirty(*ptep
));
745 if (ptep_set_access_flags(vma
, address
, ptep
, entry
, 1)) {
746 update_mmu_cache(vma
, address
, entry
);
751 int copy_hugetlb_page_range(struct mm_struct
*dst
, struct mm_struct
*src
,
752 struct vm_area_struct
*vma
)
754 pte_t
*src_pte
, *dst_pte
, entry
;
755 struct page
*ptepage
;
759 cow
= (vma
->vm_flags
& (VM_SHARED
| VM_MAYWRITE
)) == VM_MAYWRITE
;
761 for (addr
= vma
->vm_start
; addr
< vma
->vm_end
; addr
+= HPAGE_SIZE
) {
762 src_pte
= huge_pte_offset(src
, addr
);
765 dst_pte
= huge_pte_alloc(dst
, addr
);
769 /* If the pagetables are shared don't copy or take references */
770 if (dst_pte
== src_pte
)
773 spin_lock(&dst
->page_table_lock
);
774 spin_lock(&src
->page_table_lock
);
775 if (!pte_none(*src_pte
)) {
777 ptep_set_wrprotect(src
, addr
, src_pte
);
779 ptepage
= pte_page(entry
);
781 set_huge_pte_at(dst
, addr
, dst_pte
, entry
);
783 spin_unlock(&src
->page_table_lock
);
784 spin_unlock(&dst
->page_table_lock
);
792 void __unmap_hugepage_range(struct vm_area_struct
*vma
, unsigned long start
,
795 struct mm_struct
*mm
= vma
->vm_mm
;
796 unsigned long address
;
802 * A page gathering list, protected by per file i_mmap_lock. The
803 * lock is used to avoid list corruption from multiple unmapping
804 * of the same page since we are using page->lru.
806 LIST_HEAD(page_list
);
808 WARN_ON(!is_vm_hugetlb_page(vma
));
809 BUG_ON(start
& ~HPAGE_MASK
);
810 BUG_ON(end
& ~HPAGE_MASK
);
812 spin_lock(&mm
->page_table_lock
);
813 for (address
= start
; address
< end
; address
+= HPAGE_SIZE
) {
814 ptep
= huge_pte_offset(mm
, address
);
818 if (huge_pmd_unshare(mm
, &address
, ptep
))
821 pte
= huge_ptep_get_and_clear(mm
, address
, ptep
);
825 page
= pte_page(pte
);
827 set_page_dirty(page
);
828 list_add(&page
->lru
, &page_list
);
830 spin_unlock(&mm
->page_table_lock
);
831 flush_tlb_range(vma
, start
, end
);
832 list_for_each_entry_safe(page
, tmp
, &page_list
, lru
) {
833 list_del(&page
->lru
);
838 void unmap_hugepage_range(struct vm_area_struct
*vma
, unsigned long start
,
842 * It is undesirable to test vma->vm_file as it should be non-null
843 * for valid hugetlb area. However, vm_file will be NULL in the error
844 * cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails,
845 * do_mmap_pgoff() nullifies vma->vm_file before calling this function
846 * to clean up. Since no pte has actually been setup, it is safe to
847 * do nothing in this case.
850 spin_lock(&vma
->vm_file
->f_mapping
->i_mmap_lock
);
851 __unmap_hugepage_range(vma
, start
, end
);
852 spin_unlock(&vma
->vm_file
->f_mapping
->i_mmap_lock
);
856 static int hugetlb_cow(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
857 unsigned long address
, pte_t
*ptep
, pte_t pte
)
859 struct page
*old_page
, *new_page
;
862 old_page
= pte_page(pte
);
864 /* If no-one else is actually using this page, avoid the copy
865 * and just make the page writable */
866 avoidcopy
= (page_count(old_page
) == 1);
868 set_huge_ptep_writable(vma
, address
, ptep
);
872 page_cache_get(old_page
);
873 new_page
= alloc_huge_page(vma
, address
);
875 if (IS_ERR(new_page
)) {
876 page_cache_release(old_page
);
877 return -PTR_ERR(new_page
);
880 spin_unlock(&mm
->page_table_lock
);
881 copy_huge_page(new_page
, old_page
, address
, vma
);
882 __SetPageUptodate(new_page
);
883 spin_lock(&mm
->page_table_lock
);
885 ptep
= huge_pte_offset(mm
, address
& HPAGE_MASK
);
886 if (likely(pte_same(*ptep
, pte
))) {
888 set_huge_pte_at(mm
, address
, ptep
,
889 make_huge_pte(vma
, new_page
, 1));
890 /* Make the old page be freed below */
893 page_cache_release(new_page
);
894 page_cache_release(old_page
);
898 static int hugetlb_no_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
899 unsigned long address
, pte_t
*ptep
, int write_access
)
901 int ret
= VM_FAULT_SIGBUS
;
905 struct address_space
*mapping
;
908 mapping
= vma
->vm_file
->f_mapping
;
909 idx
= ((address
- vma
->vm_start
) >> HPAGE_SHIFT
)
910 + (vma
->vm_pgoff
>> (HPAGE_SHIFT
- PAGE_SHIFT
));
913 * Use page lock to guard against racing truncation
914 * before we get page_table_lock.
917 page
= find_lock_page(mapping
, idx
);
919 size
= i_size_read(mapping
->host
) >> HPAGE_SHIFT
;
922 page
= alloc_huge_page(vma
, address
);
924 ret
= -PTR_ERR(page
);
927 clear_huge_page(page
, address
);
928 __SetPageUptodate(page
);
930 if (vma
->vm_flags
& VM_SHARED
) {
932 struct inode
*inode
= mapping
->host
;
934 err
= add_to_page_cache(page
, mapping
, idx
, GFP_KERNEL
);
942 spin_lock(&inode
->i_lock
);
943 inode
->i_blocks
+= BLOCKS_PER_HUGEPAGE
;
944 spin_unlock(&inode
->i_lock
);
949 spin_lock(&mm
->page_table_lock
);
950 size
= i_size_read(mapping
->host
) >> HPAGE_SHIFT
;
955 if (!pte_none(*ptep
))
958 new_pte
= make_huge_pte(vma
, page
, ((vma
->vm_flags
& VM_WRITE
)
959 && (vma
->vm_flags
& VM_SHARED
)));
960 set_huge_pte_at(mm
, address
, ptep
, new_pte
);
962 if (write_access
&& !(vma
->vm_flags
& VM_SHARED
)) {
963 /* Optimization, do the COW without a second fault */
964 ret
= hugetlb_cow(mm
, vma
, address
, ptep
, new_pte
);
967 spin_unlock(&mm
->page_table_lock
);
973 spin_unlock(&mm
->page_table_lock
);
979 int hugetlb_fault(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
980 unsigned long address
, int write_access
)
985 static DEFINE_MUTEX(hugetlb_instantiation_mutex
);
987 ptep
= huge_pte_alloc(mm
, address
);
992 * Serialize hugepage allocation and instantiation, so that we don't
993 * get spurious allocation failures if two CPUs race to instantiate
994 * the same page in the page cache.
996 mutex_lock(&hugetlb_instantiation_mutex
);
998 if (pte_none(entry
)) {
999 ret
= hugetlb_no_page(mm
, vma
, address
, ptep
, write_access
);
1000 mutex_unlock(&hugetlb_instantiation_mutex
);
1006 spin_lock(&mm
->page_table_lock
);
1007 /* Check for a racing update before calling hugetlb_cow */
1008 if (likely(pte_same(entry
, *ptep
)))
1009 if (write_access
&& !pte_write(entry
))
1010 ret
= hugetlb_cow(mm
, vma
, address
, ptep
, entry
);
1011 spin_unlock(&mm
->page_table_lock
);
1012 mutex_unlock(&hugetlb_instantiation_mutex
);
1017 int follow_hugetlb_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1018 struct page
**pages
, struct vm_area_struct
**vmas
,
1019 unsigned long *position
, int *length
, int i
,
1022 unsigned long pfn_offset
;
1023 unsigned long vaddr
= *position
;
1024 int remainder
= *length
;
1026 spin_lock(&mm
->page_table_lock
);
1027 while (vaddr
< vma
->vm_end
&& remainder
) {
1032 * Some archs (sparc64, sh*) have multiple pte_ts to
1033 * each hugepage. We have to make * sure we get the
1034 * first, for the page indexing below to work.
1036 pte
= huge_pte_offset(mm
, vaddr
& HPAGE_MASK
);
1038 if (!pte
|| pte_none(*pte
) || (write
&& !pte_write(*pte
))) {
1041 spin_unlock(&mm
->page_table_lock
);
1042 ret
= hugetlb_fault(mm
, vma
, vaddr
, write
);
1043 spin_lock(&mm
->page_table_lock
);
1044 if (!(ret
& VM_FAULT_ERROR
))
1053 pfn_offset
= (vaddr
& ~HPAGE_MASK
) >> PAGE_SHIFT
;
1054 page
= pte_page(*pte
);
1058 pages
[i
] = page
+ pfn_offset
;
1068 if (vaddr
< vma
->vm_end
&& remainder
&&
1069 pfn_offset
< HPAGE_SIZE
/PAGE_SIZE
) {
1071 * We use pfn_offset to avoid touching the pageframes
1072 * of this compound page.
1077 spin_unlock(&mm
->page_table_lock
);
1078 *length
= remainder
;
1084 void hugetlb_change_protection(struct vm_area_struct
*vma
,
1085 unsigned long address
, unsigned long end
, pgprot_t newprot
)
1087 struct mm_struct
*mm
= vma
->vm_mm
;
1088 unsigned long start
= address
;
1092 BUG_ON(address
>= end
);
1093 flush_cache_range(vma
, address
, end
);
1095 spin_lock(&vma
->vm_file
->f_mapping
->i_mmap_lock
);
1096 spin_lock(&mm
->page_table_lock
);
1097 for (; address
< end
; address
+= HPAGE_SIZE
) {
1098 ptep
= huge_pte_offset(mm
, address
);
1101 if (huge_pmd_unshare(mm
, &address
, ptep
))
1103 if (!pte_none(*ptep
)) {
1104 pte
= huge_ptep_get_and_clear(mm
, address
, ptep
);
1105 pte
= pte_mkhuge(pte_modify(pte
, newprot
));
1106 set_huge_pte_at(mm
, address
, ptep
, pte
);
1109 spin_unlock(&mm
->page_table_lock
);
1110 spin_unlock(&vma
->vm_file
->f_mapping
->i_mmap_lock
);
1112 flush_tlb_range(vma
, start
, end
);
1115 struct file_region
{
1116 struct list_head link
;
1121 static long region_add(struct list_head
*head
, long f
, long t
)
1123 struct file_region
*rg
, *nrg
, *trg
;
1125 /* Locate the region we are either in or before. */
1126 list_for_each_entry(rg
, head
, link
)
1130 /* Round our left edge to the current segment if it encloses us. */
1134 /* Check for and consume any regions we now overlap with. */
1136 list_for_each_entry_safe(rg
, trg
, rg
->link
.prev
, link
) {
1137 if (&rg
->link
== head
)
1142 /* If this area reaches higher then extend our area to
1143 * include it completely. If this is not the first area
1144 * which we intend to reuse, free it. */
1148 list_del(&rg
->link
);
1157 static long region_chg(struct list_head
*head
, long f
, long t
)
1159 struct file_region
*rg
, *nrg
;
1162 /* Locate the region we are before or in. */
1163 list_for_each_entry(rg
, head
, link
)
1167 /* If we are below the current region then a new region is required.
1168 * Subtle, allocate a new region at the position but make it zero
1169 * size such that we can guarantee to record the reservation. */
1170 if (&rg
->link
== head
|| t
< rg
->from
) {
1171 nrg
= kmalloc(sizeof(*nrg
), GFP_KERNEL
);
1176 INIT_LIST_HEAD(&nrg
->link
);
1177 list_add(&nrg
->link
, rg
->link
.prev
);
1182 /* Round our left edge to the current segment if it encloses us. */
1187 /* Check for and consume any regions we now overlap with. */
1188 list_for_each_entry(rg
, rg
->link
.prev
, link
) {
1189 if (&rg
->link
== head
)
1194 /* We overlap with this area, if it extends futher than
1195 * us then we must extend ourselves. Account for its
1196 * existing reservation. */
1201 chg
-= rg
->to
- rg
->from
;
1206 static long region_truncate(struct list_head
*head
, long end
)
1208 struct file_region
*rg
, *trg
;
1211 /* Locate the region we are either in or before. */
1212 list_for_each_entry(rg
, head
, link
)
1215 if (&rg
->link
== head
)
1218 /* If we are in the middle of a region then adjust it. */
1219 if (end
> rg
->from
) {
1222 rg
= list_entry(rg
->link
.next
, typeof(*rg
), link
);
1225 /* Drop any remaining regions. */
1226 list_for_each_entry_safe(rg
, trg
, rg
->link
.prev
, link
) {
1227 if (&rg
->link
== head
)
1229 chg
+= rg
->to
- rg
->from
;
1230 list_del(&rg
->link
);
1236 static int hugetlb_acct_memory(long delta
)
1240 spin_lock(&hugetlb_lock
);
1242 * When cpuset is configured, it breaks the strict hugetlb page
1243 * reservation as the accounting is done on a global variable. Such
1244 * reservation is completely rubbish in the presence of cpuset because
1245 * the reservation is not checked against page availability for the
1246 * current cpuset. Application can still potentially OOM'ed by kernel
1247 * with lack of free htlb page in cpuset that the task is in.
1248 * Attempt to enforce strict accounting with cpuset is almost
1249 * impossible (or too ugly) because cpuset is too fluid that
1250 * task or memory node can be dynamically moved between cpusets.
1252 * The change of semantics for shared hugetlb mapping with cpuset is
1253 * undesirable. However, in order to preserve some of the semantics,
1254 * we fall back to check against current free page availability as
1255 * a best attempt and hopefully to minimize the impact of changing
1256 * semantics that cpuset has.
1259 if (gather_surplus_pages(delta
) < 0)
1262 if (delta
> cpuset_mems_nr(free_huge_pages_node
)) {
1263 return_unused_surplus_pages(delta
);
1270 return_unused_surplus_pages((unsigned long) -delta
);
1273 spin_unlock(&hugetlb_lock
);
1277 int hugetlb_reserve_pages(struct inode
*inode
, long from
, long to
)
1281 chg
= region_chg(&inode
->i_mapping
->private_list
, from
, to
);
1285 if (hugetlb_get_quota(inode
->i_mapping
, chg
))
1287 ret
= hugetlb_acct_memory(chg
);
1289 hugetlb_put_quota(inode
->i_mapping
, chg
);
1292 region_add(&inode
->i_mapping
->private_list
, from
, to
);
1296 void hugetlb_unreserve_pages(struct inode
*inode
, long offset
, long freed
)
1298 long chg
= region_truncate(&inode
->i_mapping
->private_list
, offset
);
1300 spin_lock(&inode
->i_lock
);
1301 inode
->i_blocks
-= BLOCKS_PER_HUGEPAGE
* freed
;
1302 spin_unlock(&inode
->i_lock
);
1304 hugetlb_put_quota(inode
->i_mapping
, (chg
- freed
));
1305 hugetlb_acct_memory(-(chg
- freed
));