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
)
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
);
246 count_vm_event(HTLB_BUDDY_PGALLOC
);
248 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL
);
253 static struct page
*alloc_buddy_huge_page(struct vm_area_struct
*vma
,
254 unsigned long address
)
260 * Assume we will successfully allocate the surplus page to
261 * prevent racing processes from causing the surplus to exceed
264 * This however introduces a different race, where a process B
265 * tries to grow the static hugepage pool while alloc_pages() is
266 * called by process A. B will only examine the per-node
267 * counters in determining if surplus huge pages can be
268 * converted to normal huge pages in adjust_pool_surplus(). A
269 * won't be able to increment the per-node counter, until the
270 * lock is dropped by B, but B doesn't drop hugetlb_lock until
271 * no more huge pages can be converted from surplus to normal
272 * state (and doesn't try to convert again). Thus, we have a
273 * case where a surplus huge page exists, the pool is grown, and
274 * the surplus huge page still exists after, even though it
275 * should just have been converted to a normal huge page. This
276 * does not leak memory, though, as the hugepage will be freed
277 * once it is out of use. It also does not allow the counters to
278 * go out of whack in adjust_pool_surplus() as we don't modify
279 * the node values until we've gotten the hugepage and only the
280 * per-node value is checked there.
282 spin_lock(&hugetlb_lock
);
283 if (surplus_huge_pages
>= nr_overcommit_huge_pages
) {
284 spin_unlock(&hugetlb_lock
);
288 surplus_huge_pages
++;
290 spin_unlock(&hugetlb_lock
);
292 page
= alloc_pages(htlb_alloc_mask
|__GFP_COMP
|__GFP_NOWARN
,
295 spin_lock(&hugetlb_lock
);
298 * This page is now managed by the hugetlb allocator and has
299 * no users -- drop the buddy allocator's reference.
301 put_page_testzero(page
);
302 VM_BUG_ON(page_count(page
));
303 nid
= page_to_nid(page
);
304 set_compound_page_dtor(page
, free_huge_page
);
306 * We incremented the global counters already
308 nr_huge_pages_node
[nid
]++;
309 surplus_huge_pages_node
[nid
]++;
310 __count_vm_event(HTLB_BUDDY_PGALLOC
);
313 surplus_huge_pages
--;
314 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL
);
316 spin_unlock(&hugetlb_lock
);
322 * Increase the hugetlb pool such that it can accomodate a reservation
325 static int gather_surplus_pages(int delta
)
327 struct list_head surplus_list
;
328 struct page
*page
, *tmp
;
330 int needed
, allocated
;
332 needed
= (resv_huge_pages
+ delta
) - free_huge_pages
;
334 resv_huge_pages
+= delta
;
339 INIT_LIST_HEAD(&surplus_list
);
343 spin_unlock(&hugetlb_lock
);
344 for (i
= 0; i
< needed
; i
++) {
345 page
= alloc_buddy_huge_page(NULL
, 0);
348 * We were not able to allocate enough pages to
349 * satisfy the entire reservation so we free what
350 * we've allocated so far.
352 spin_lock(&hugetlb_lock
);
357 list_add(&page
->lru
, &surplus_list
);
362 * After retaking hugetlb_lock, we need to recalculate 'needed'
363 * because either resv_huge_pages or free_huge_pages may have changed.
365 spin_lock(&hugetlb_lock
);
366 needed
= (resv_huge_pages
+ delta
) - (free_huge_pages
+ allocated
);
371 * The surplus_list now contains _at_least_ the number of extra pages
372 * needed to accomodate the reservation. Add the appropriate number
373 * of pages to the hugetlb pool and free the extras back to the buddy
374 * allocator. Commit the entire reservation here to prevent another
375 * process from stealing the pages as they are added to the pool but
376 * before they are reserved.
379 resv_huge_pages
+= delta
;
382 /* Free the needed pages to the hugetlb pool */
383 list_for_each_entry_safe(page
, tmp
, &surplus_list
, lru
) {
386 list_del(&page
->lru
);
387 enqueue_huge_page(page
);
390 /* Free unnecessary surplus pages to the buddy allocator */
391 if (!list_empty(&surplus_list
)) {
392 spin_unlock(&hugetlb_lock
);
393 list_for_each_entry_safe(page
, tmp
, &surplus_list
, lru
) {
394 list_del(&page
->lru
);
396 * The page has a reference count of zero already, so
397 * call free_huge_page directly instead of using
398 * put_page. This must be done with hugetlb_lock
399 * unlocked which is safe because free_huge_page takes
400 * hugetlb_lock before deciding how to free the page.
402 free_huge_page(page
);
404 spin_lock(&hugetlb_lock
);
411 * When releasing a hugetlb pool reservation, any surplus pages that were
412 * allocated to satisfy the reservation must be explicitly freed if they were
415 static void return_unused_surplus_pages(unsigned long unused_resv_pages
)
419 unsigned long nr_pages
;
422 * We want to release as many surplus pages as possible, spread
423 * evenly across all nodes. Iterate across all nodes until we
424 * can no longer free unreserved surplus pages. This occurs when
425 * the nodes with surplus pages have no free pages.
427 unsigned long remaining_iterations
= num_online_nodes();
429 /* Uncommit the reservation */
430 resv_huge_pages
-= unused_resv_pages
;
432 nr_pages
= min(unused_resv_pages
, surplus_huge_pages
);
434 while (remaining_iterations
-- && nr_pages
) {
435 nid
= next_node(nid
, node_online_map
);
436 if (nid
== MAX_NUMNODES
)
437 nid
= first_node(node_online_map
);
439 if (!surplus_huge_pages_node
[nid
])
442 if (!list_empty(&hugepage_freelists
[nid
])) {
443 page
= list_entry(hugepage_freelists
[nid
].next
,
445 list_del(&page
->lru
);
446 update_and_free_page(page
);
448 free_huge_pages_node
[nid
]--;
449 surplus_huge_pages
--;
450 surplus_huge_pages_node
[nid
]--;
452 remaining_iterations
= num_online_nodes();
458 static struct page
*alloc_huge_page_shared(struct vm_area_struct
*vma
,
463 spin_lock(&hugetlb_lock
);
464 page
= dequeue_huge_page_vma(vma
, addr
);
465 spin_unlock(&hugetlb_lock
);
466 return page
? page
: ERR_PTR(-VM_FAULT_OOM
);
469 static struct page
*alloc_huge_page_private(struct vm_area_struct
*vma
,
472 struct page
*page
= NULL
;
474 if (hugetlb_get_quota(vma
->vm_file
->f_mapping
, 1))
475 return ERR_PTR(-VM_FAULT_SIGBUS
);
477 spin_lock(&hugetlb_lock
);
478 if (free_huge_pages
> resv_huge_pages
)
479 page
= dequeue_huge_page_vma(vma
, addr
);
480 spin_unlock(&hugetlb_lock
);
482 page
= alloc_buddy_huge_page(vma
, addr
);
484 hugetlb_put_quota(vma
->vm_file
->f_mapping
, 1);
485 return ERR_PTR(-VM_FAULT_OOM
);
491 static struct page
*alloc_huge_page(struct vm_area_struct
*vma
,
495 struct address_space
*mapping
= vma
->vm_file
->f_mapping
;
497 if (vma
->vm_flags
& VM_MAYSHARE
)
498 page
= alloc_huge_page_shared(vma
, addr
);
500 page
= alloc_huge_page_private(vma
, addr
);
503 set_page_refcounted(page
);
504 set_page_private(page
, (unsigned long) mapping
);
509 static int __init
hugetlb_init(void)
513 if (HPAGE_SHIFT
== 0)
516 for (i
= 0; i
< MAX_NUMNODES
; ++i
)
517 INIT_LIST_HEAD(&hugepage_freelists
[i
]);
519 hugetlb_next_nid
= first_node(node_online_map
);
521 for (i
= 0; i
< max_huge_pages
; ++i
) {
522 if (!alloc_fresh_huge_page())
525 max_huge_pages
= free_huge_pages
= nr_huge_pages
= i
;
526 printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages
);
529 module_init(hugetlb_init
);
531 static int __init
hugetlb_setup(char *s
)
533 if (sscanf(s
, "%lu", &max_huge_pages
) <= 0)
537 __setup("hugepages=", hugetlb_setup
);
539 static unsigned int cpuset_mems_nr(unsigned int *array
)
544 for_each_node_mask(node
, cpuset_current_mems_allowed
)
551 #ifdef CONFIG_HIGHMEM
552 static void try_to_free_low(unsigned long count
)
556 for (i
= 0; i
< MAX_NUMNODES
; ++i
) {
557 struct page
*page
, *next
;
558 list_for_each_entry_safe(page
, next
, &hugepage_freelists
[i
], lru
) {
559 if (count
>= nr_huge_pages
)
561 if (PageHighMem(page
))
563 list_del(&page
->lru
);
564 update_and_free_page(page
);
566 free_huge_pages_node
[page_to_nid(page
)]--;
571 static inline void try_to_free_low(unsigned long count
)
576 #define persistent_huge_pages (nr_huge_pages - surplus_huge_pages)
577 static unsigned long set_max_huge_pages(unsigned long count
)
579 unsigned long min_count
, ret
;
582 * Increase the pool size
583 * First take pages out of surplus state. Then make up the
584 * remaining difference by allocating fresh huge pages.
586 * We might race with alloc_buddy_huge_page() here and be unable
587 * to convert a surplus huge page to a normal huge page. That is
588 * not critical, though, it just means the overall size of the
589 * pool might be one hugepage larger than it needs to be, but
590 * within all the constraints specified by the sysctls.
592 spin_lock(&hugetlb_lock
);
593 while (surplus_huge_pages
&& count
> persistent_huge_pages
) {
594 if (!adjust_pool_surplus(-1))
598 while (count
> persistent_huge_pages
) {
601 * If this allocation races such that we no longer need the
602 * page, free_huge_page will handle it by freeing the page
603 * and reducing the surplus.
605 spin_unlock(&hugetlb_lock
);
606 ret
= alloc_fresh_huge_page();
607 spin_lock(&hugetlb_lock
);
614 * Decrease the pool size
615 * First return free pages to the buddy allocator (being careful
616 * to keep enough around to satisfy reservations). Then place
617 * pages into surplus state as needed so the pool will shrink
618 * to the desired size as pages become free.
620 * By placing pages into the surplus state independent of the
621 * overcommit value, we are allowing the surplus pool size to
622 * exceed overcommit. There are few sane options here. Since
623 * alloc_buddy_huge_page() is checking the global counter,
624 * though, we'll note that we're not allowed to exceed surplus
625 * and won't grow the pool anywhere else. Not until one of the
626 * sysctls are changed, or the surplus pages go out of use.
628 min_count
= resv_huge_pages
+ nr_huge_pages
- free_huge_pages
;
629 min_count
= max(count
, min_count
);
630 try_to_free_low(min_count
);
631 while (min_count
< persistent_huge_pages
) {
632 struct page
*page
= dequeue_huge_page();
635 update_and_free_page(page
);
637 while (count
< persistent_huge_pages
) {
638 if (!adjust_pool_surplus(1))
642 ret
= persistent_huge_pages
;
643 spin_unlock(&hugetlb_lock
);
647 int hugetlb_sysctl_handler(struct ctl_table
*table
, int write
,
648 struct file
*file
, void __user
*buffer
,
649 size_t *length
, loff_t
*ppos
)
651 proc_doulongvec_minmax(table
, write
, file
, buffer
, length
, ppos
);
652 max_huge_pages
= set_max_huge_pages(max_huge_pages
);
656 int hugetlb_treat_movable_handler(struct ctl_table
*table
, int write
,
657 struct file
*file
, void __user
*buffer
,
658 size_t *length
, loff_t
*ppos
)
660 proc_dointvec(table
, write
, file
, buffer
, length
, ppos
);
661 if (hugepages_treat_as_movable
)
662 htlb_alloc_mask
= GFP_HIGHUSER_MOVABLE
;
664 htlb_alloc_mask
= GFP_HIGHUSER
;
668 int hugetlb_overcommit_handler(struct ctl_table
*table
, int write
,
669 struct file
*file
, void __user
*buffer
,
670 size_t *length
, loff_t
*ppos
)
672 proc_doulongvec_minmax(table
, write
, file
, buffer
, length
, ppos
);
673 spin_lock(&hugetlb_lock
);
674 nr_overcommit_huge_pages
= sysctl_overcommit_huge_pages
;
675 spin_unlock(&hugetlb_lock
);
679 #endif /* CONFIG_SYSCTL */
681 int hugetlb_report_meminfo(char *buf
)
684 "HugePages_Total: %5lu\n"
685 "HugePages_Free: %5lu\n"
686 "HugePages_Rsvd: %5lu\n"
687 "HugePages_Surp: %5lu\n"
688 "Hugepagesize: %5lu kB\n",
696 int hugetlb_report_node_meminfo(int nid
, char *buf
)
699 "Node %d HugePages_Total: %5u\n"
700 "Node %d HugePages_Free: %5u\n"
701 "Node %d HugePages_Surp: %5u\n",
702 nid
, nr_huge_pages_node
[nid
],
703 nid
, free_huge_pages_node
[nid
],
704 nid
, surplus_huge_pages_node
[nid
]);
707 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
708 unsigned long hugetlb_total_pages(void)
710 return nr_huge_pages
* (HPAGE_SIZE
/ PAGE_SIZE
);
714 * We cannot handle pagefaults against hugetlb pages at all. They cause
715 * handle_mm_fault() to try to instantiate regular-sized pages in the
716 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
719 static int hugetlb_vm_op_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
725 struct vm_operations_struct hugetlb_vm_ops
= {
726 .fault
= hugetlb_vm_op_fault
,
729 static pte_t
make_huge_pte(struct vm_area_struct
*vma
, struct page
*page
,
736 pte_mkwrite(pte_mkdirty(mk_pte(page
, vma
->vm_page_prot
)));
738 entry
= pte_wrprotect(mk_pte(page
, vma
->vm_page_prot
));
740 entry
= pte_mkyoung(entry
);
741 entry
= pte_mkhuge(entry
);
746 static void set_huge_ptep_writable(struct vm_area_struct
*vma
,
747 unsigned long address
, pte_t
*ptep
)
751 entry
= pte_mkwrite(pte_mkdirty(*ptep
));
752 if (ptep_set_access_flags(vma
, address
, ptep
, entry
, 1)) {
753 update_mmu_cache(vma
, address
, entry
);
758 int copy_hugetlb_page_range(struct mm_struct
*dst
, struct mm_struct
*src
,
759 struct vm_area_struct
*vma
)
761 pte_t
*src_pte
, *dst_pte
, entry
;
762 struct page
*ptepage
;
766 cow
= (vma
->vm_flags
& (VM_SHARED
| VM_MAYWRITE
)) == VM_MAYWRITE
;
768 for (addr
= vma
->vm_start
; addr
< vma
->vm_end
; addr
+= HPAGE_SIZE
) {
769 src_pte
= huge_pte_offset(src
, addr
);
772 dst_pte
= huge_pte_alloc(dst
, addr
);
776 /* If the pagetables are shared don't copy or take references */
777 if (dst_pte
== src_pte
)
780 spin_lock(&dst
->page_table_lock
);
781 spin_lock(&src
->page_table_lock
);
782 if (!pte_none(*src_pte
)) {
784 ptep_set_wrprotect(src
, addr
, src_pte
);
786 ptepage
= pte_page(entry
);
788 set_huge_pte_at(dst
, addr
, dst_pte
, entry
);
790 spin_unlock(&src
->page_table_lock
);
791 spin_unlock(&dst
->page_table_lock
);
799 void __unmap_hugepage_range(struct vm_area_struct
*vma
, unsigned long start
,
802 struct mm_struct
*mm
= vma
->vm_mm
;
803 unsigned long address
;
809 * A page gathering list, protected by per file i_mmap_lock. The
810 * lock is used to avoid list corruption from multiple unmapping
811 * of the same page since we are using page->lru.
813 LIST_HEAD(page_list
);
815 WARN_ON(!is_vm_hugetlb_page(vma
));
816 BUG_ON(start
& ~HPAGE_MASK
);
817 BUG_ON(end
& ~HPAGE_MASK
);
819 spin_lock(&mm
->page_table_lock
);
820 for (address
= start
; address
< end
; address
+= HPAGE_SIZE
) {
821 ptep
= huge_pte_offset(mm
, address
);
825 if (huge_pmd_unshare(mm
, &address
, ptep
))
828 pte
= huge_ptep_get_and_clear(mm
, address
, ptep
);
832 page
= pte_page(pte
);
834 set_page_dirty(page
);
835 list_add(&page
->lru
, &page_list
);
837 spin_unlock(&mm
->page_table_lock
);
838 flush_tlb_range(vma
, start
, end
);
839 list_for_each_entry_safe(page
, tmp
, &page_list
, lru
) {
840 list_del(&page
->lru
);
845 void unmap_hugepage_range(struct vm_area_struct
*vma
, unsigned long start
,
849 * It is undesirable to test vma->vm_file as it should be non-null
850 * for valid hugetlb area. However, vm_file will be NULL in the error
851 * cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails,
852 * do_mmap_pgoff() nullifies vma->vm_file before calling this function
853 * to clean up. Since no pte has actually been setup, it is safe to
854 * do nothing in this case.
857 spin_lock(&vma
->vm_file
->f_mapping
->i_mmap_lock
);
858 __unmap_hugepage_range(vma
, start
, end
);
859 spin_unlock(&vma
->vm_file
->f_mapping
->i_mmap_lock
);
863 static int hugetlb_cow(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
864 unsigned long address
, pte_t
*ptep
, pte_t pte
)
866 struct page
*old_page
, *new_page
;
869 old_page
= pte_page(pte
);
871 /* If no-one else is actually using this page, avoid the copy
872 * and just make the page writable */
873 avoidcopy
= (page_count(old_page
) == 1);
875 set_huge_ptep_writable(vma
, address
, ptep
);
879 page_cache_get(old_page
);
880 new_page
= alloc_huge_page(vma
, address
);
882 if (IS_ERR(new_page
)) {
883 page_cache_release(old_page
);
884 return -PTR_ERR(new_page
);
887 spin_unlock(&mm
->page_table_lock
);
888 copy_huge_page(new_page
, old_page
, address
, vma
);
889 __SetPageUptodate(new_page
);
890 spin_lock(&mm
->page_table_lock
);
892 ptep
= huge_pte_offset(mm
, address
& HPAGE_MASK
);
893 if (likely(pte_same(*ptep
, pte
))) {
895 set_huge_pte_at(mm
, address
, ptep
,
896 make_huge_pte(vma
, new_page
, 1));
897 /* Make the old page be freed below */
900 page_cache_release(new_page
);
901 page_cache_release(old_page
);
905 static int hugetlb_no_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
906 unsigned long address
, pte_t
*ptep
, int write_access
)
908 int ret
= VM_FAULT_SIGBUS
;
912 struct address_space
*mapping
;
915 mapping
= vma
->vm_file
->f_mapping
;
916 idx
= ((address
- vma
->vm_start
) >> HPAGE_SHIFT
)
917 + (vma
->vm_pgoff
>> (HPAGE_SHIFT
- PAGE_SHIFT
));
920 * Use page lock to guard against racing truncation
921 * before we get page_table_lock.
924 page
= find_lock_page(mapping
, idx
);
926 size
= i_size_read(mapping
->host
) >> HPAGE_SHIFT
;
929 page
= alloc_huge_page(vma
, address
);
931 ret
= -PTR_ERR(page
);
934 clear_huge_page(page
, address
);
935 __SetPageUptodate(page
);
937 if (vma
->vm_flags
& VM_SHARED
) {
939 struct inode
*inode
= mapping
->host
;
941 err
= add_to_page_cache(page
, mapping
, idx
, GFP_KERNEL
);
949 spin_lock(&inode
->i_lock
);
950 inode
->i_blocks
+= BLOCKS_PER_HUGEPAGE
;
951 spin_unlock(&inode
->i_lock
);
956 spin_lock(&mm
->page_table_lock
);
957 size
= i_size_read(mapping
->host
) >> HPAGE_SHIFT
;
962 if (!pte_none(*ptep
))
965 new_pte
= make_huge_pte(vma
, page
, ((vma
->vm_flags
& VM_WRITE
)
966 && (vma
->vm_flags
& VM_SHARED
)));
967 set_huge_pte_at(mm
, address
, ptep
, new_pte
);
969 if (write_access
&& !(vma
->vm_flags
& VM_SHARED
)) {
970 /* Optimization, do the COW without a second fault */
971 ret
= hugetlb_cow(mm
, vma
, address
, ptep
, new_pte
);
974 spin_unlock(&mm
->page_table_lock
);
980 spin_unlock(&mm
->page_table_lock
);
986 int hugetlb_fault(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
987 unsigned long address
, int write_access
)
992 static DEFINE_MUTEX(hugetlb_instantiation_mutex
);
994 ptep
= huge_pte_alloc(mm
, address
);
999 * Serialize hugepage allocation and instantiation, so that we don't
1000 * get spurious allocation failures if two CPUs race to instantiate
1001 * the same page in the page cache.
1003 mutex_lock(&hugetlb_instantiation_mutex
);
1005 if (pte_none(entry
)) {
1006 ret
= hugetlb_no_page(mm
, vma
, address
, ptep
, write_access
);
1007 mutex_unlock(&hugetlb_instantiation_mutex
);
1013 spin_lock(&mm
->page_table_lock
);
1014 /* Check for a racing update before calling hugetlb_cow */
1015 if (likely(pte_same(entry
, *ptep
)))
1016 if (write_access
&& !pte_write(entry
))
1017 ret
= hugetlb_cow(mm
, vma
, address
, ptep
, entry
);
1018 spin_unlock(&mm
->page_table_lock
);
1019 mutex_unlock(&hugetlb_instantiation_mutex
);
1024 int follow_hugetlb_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1025 struct page
**pages
, struct vm_area_struct
**vmas
,
1026 unsigned long *position
, int *length
, int i
,
1029 unsigned long pfn_offset
;
1030 unsigned long vaddr
= *position
;
1031 int remainder
= *length
;
1033 spin_lock(&mm
->page_table_lock
);
1034 while (vaddr
< vma
->vm_end
&& remainder
) {
1039 * Some archs (sparc64, sh*) have multiple pte_ts to
1040 * each hugepage. We have to make * sure we get the
1041 * first, for the page indexing below to work.
1043 pte
= huge_pte_offset(mm
, vaddr
& HPAGE_MASK
);
1045 if (!pte
|| pte_none(*pte
) || (write
&& !pte_write(*pte
))) {
1048 spin_unlock(&mm
->page_table_lock
);
1049 ret
= hugetlb_fault(mm
, vma
, vaddr
, write
);
1050 spin_lock(&mm
->page_table_lock
);
1051 if (!(ret
& VM_FAULT_ERROR
))
1060 pfn_offset
= (vaddr
& ~HPAGE_MASK
) >> PAGE_SHIFT
;
1061 page
= pte_page(*pte
);
1065 pages
[i
] = page
+ pfn_offset
;
1075 if (vaddr
< vma
->vm_end
&& remainder
&&
1076 pfn_offset
< HPAGE_SIZE
/PAGE_SIZE
) {
1078 * We use pfn_offset to avoid touching the pageframes
1079 * of this compound page.
1084 spin_unlock(&mm
->page_table_lock
);
1085 *length
= remainder
;
1091 void hugetlb_change_protection(struct vm_area_struct
*vma
,
1092 unsigned long address
, unsigned long end
, pgprot_t newprot
)
1094 struct mm_struct
*mm
= vma
->vm_mm
;
1095 unsigned long start
= address
;
1099 BUG_ON(address
>= end
);
1100 flush_cache_range(vma
, address
, end
);
1102 spin_lock(&vma
->vm_file
->f_mapping
->i_mmap_lock
);
1103 spin_lock(&mm
->page_table_lock
);
1104 for (; address
< end
; address
+= HPAGE_SIZE
) {
1105 ptep
= huge_pte_offset(mm
, address
);
1108 if (huge_pmd_unshare(mm
, &address
, ptep
))
1110 if (!pte_none(*ptep
)) {
1111 pte
= huge_ptep_get_and_clear(mm
, address
, ptep
);
1112 pte
= pte_mkhuge(pte_modify(pte
, newprot
));
1113 set_huge_pte_at(mm
, address
, ptep
, pte
);
1116 spin_unlock(&mm
->page_table_lock
);
1117 spin_unlock(&vma
->vm_file
->f_mapping
->i_mmap_lock
);
1119 flush_tlb_range(vma
, start
, end
);
1122 struct file_region
{
1123 struct list_head link
;
1128 static long region_add(struct list_head
*head
, long f
, long t
)
1130 struct file_region
*rg
, *nrg
, *trg
;
1132 /* Locate the region we are either in or before. */
1133 list_for_each_entry(rg
, head
, link
)
1137 /* Round our left edge to the current segment if it encloses us. */
1141 /* Check for and consume any regions we now overlap with. */
1143 list_for_each_entry_safe(rg
, trg
, rg
->link
.prev
, link
) {
1144 if (&rg
->link
== head
)
1149 /* If this area reaches higher then extend our area to
1150 * include it completely. If this is not the first area
1151 * which we intend to reuse, free it. */
1155 list_del(&rg
->link
);
1164 static long region_chg(struct list_head
*head
, long f
, long t
)
1166 struct file_region
*rg
, *nrg
;
1169 /* Locate the region we are before or in. */
1170 list_for_each_entry(rg
, head
, link
)
1174 /* If we are below the current region then a new region is required.
1175 * Subtle, allocate a new region at the position but make it zero
1176 * size such that we can guarantee to record the reservation. */
1177 if (&rg
->link
== head
|| t
< rg
->from
) {
1178 nrg
= kmalloc(sizeof(*nrg
), GFP_KERNEL
);
1183 INIT_LIST_HEAD(&nrg
->link
);
1184 list_add(&nrg
->link
, rg
->link
.prev
);
1189 /* Round our left edge to the current segment if it encloses us. */
1194 /* Check for and consume any regions we now overlap with. */
1195 list_for_each_entry(rg
, rg
->link
.prev
, link
) {
1196 if (&rg
->link
== head
)
1201 /* We overlap with this area, if it extends futher than
1202 * us then we must extend ourselves. Account for its
1203 * existing reservation. */
1208 chg
-= rg
->to
- rg
->from
;
1213 static long region_truncate(struct list_head
*head
, long end
)
1215 struct file_region
*rg
, *trg
;
1218 /* Locate the region we are either in or before. */
1219 list_for_each_entry(rg
, head
, link
)
1222 if (&rg
->link
== head
)
1225 /* If we are in the middle of a region then adjust it. */
1226 if (end
> rg
->from
) {
1229 rg
= list_entry(rg
->link
.next
, typeof(*rg
), link
);
1232 /* Drop any remaining regions. */
1233 list_for_each_entry_safe(rg
, trg
, rg
->link
.prev
, link
) {
1234 if (&rg
->link
== head
)
1236 chg
+= rg
->to
- rg
->from
;
1237 list_del(&rg
->link
);
1243 static int hugetlb_acct_memory(long delta
)
1247 spin_lock(&hugetlb_lock
);
1249 * When cpuset is configured, it breaks the strict hugetlb page
1250 * reservation as the accounting is done on a global variable. Such
1251 * reservation is completely rubbish in the presence of cpuset because
1252 * the reservation is not checked against page availability for the
1253 * current cpuset. Application can still potentially OOM'ed by kernel
1254 * with lack of free htlb page in cpuset that the task is in.
1255 * Attempt to enforce strict accounting with cpuset is almost
1256 * impossible (or too ugly) because cpuset is too fluid that
1257 * task or memory node can be dynamically moved between cpusets.
1259 * The change of semantics for shared hugetlb mapping with cpuset is
1260 * undesirable. However, in order to preserve some of the semantics,
1261 * we fall back to check against current free page availability as
1262 * a best attempt and hopefully to minimize the impact of changing
1263 * semantics that cpuset has.
1266 if (gather_surplus_pages(delta
) < 0)
1269 if (delta
> cpuset_mems_nr(free_huge_pages_node
)) {
1270 return_unused_surplus_pages(delta
);
1277 return_unused_surplus_pages((unsigned long) -delta
);
1280 spin_unlock(&hugetlb_lock
);
1284 int hugetlb_reserve_pages(struct inode
*inode
, long from
, long to
)
1288 chg
= region_chg(&inode
->i_mapping
->private_list
, from
, to
);
1292 if (hugetlb_get_quota(inode
->i_mapping
, chg
))
1294 ret
= hugetlb_acct_memory(chg
);
1296 hugetlb_put_quota(inode
->i_mapping
, chg
);
1299 region_add(&inode
->i_mapping
->private_list
, from
, to
);
1303 void hugetlb_unreserve_pages(struct inode
*inode
, long offset
, long freed
)
1305 long chg
= region_truncate(&inode
->i_mapping
->private_list
, offset
);
1307 spin_lock(&inode
->i_lock
);
1308 inode
->i_blocks
-= BLOCKS_PER_HUGEPAGE
* freed
;
1309 spin_unlock(&inode
->i_lock
);
1311 hugetlb_put_quota(inode
->i_mapping
, (chg
- freed
));
1312 hugetlb_acct_memory(-(chg
- freed
));