1 // SPDX-License-Identifier: GPL-2.0-only
5 * Replacement code for mm functions to support CPU's that don't
6 * have any form of memory management unit (thus no virtual memory).
8 * See Documentation/admin-guide/mm/nommu-mmap.rst
10 * Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
11 * Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
12 * Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
13 * Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com>
14 * Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19 #include <linux/export.h>
21 #include <linux/sched/mm.h>
22 #include <linux/vmacache.h>
23 #include <linux/mman.h>
24 #include <linux/swap.h>
25 #include <linux/file.h>
26 #include <linux/highmem.h>
27 #include <linux/pagemap.h>
28 #include <linux/slab.h>
29 #include <linux/vmalloc.h>
30 #include <linux/blkdev.h>
31 #include <linux/backing-dev.h>
32 #include <linux/compiler.h>
33 #include <linux/mount.h>
34 #include <linux/personality.h>
35 #include <linux/security.h>
36 #include <linux/syscalls.h>
37 #include <linux/audit.h>
38 #include <linux/printk.h>
40 #include <linux/uaccess.h>
42 #include <asm/tlbflush.h>
43 #include <asm/mmu_context.h>
47 EXPORT_SYMBOL(high_memory
);
49 unsigned long max_mapnr
;
50 EXPORT_SYMBOL(max_mapnr
);
51 unsigned long highest_memmap_pfn
;
52 int sysctl_nr_trim_pages
= CONFIG_NOMMU_INITIAL_TRIM_EXCESS
;
53 int heap_stack_gap
= 0;
55 atomic_long_t mmap_pages_allocated
;
57 EXPORT_SYMBOL(mem_map
);
59 /* list of mapped, potentially shareable regions */
60 static struct kmem_cache
*vm_region_jar
;
61 struct rb_root nommu_region_tree
= RB_ROOT
;
62 DECLARE_RWSEM(nommu_region_sem
);
64 const struct vm_operations_struct generic_file_vm_ops
= {
68 * Return the total memory allocated for this pointer, not
69 * just what the caller asked for.
71 * Doesn't have to be accurate, i.e. may have races.
73 unsigned int kobjsize(const void *objp
)
78 * If the object we have should not have ksize performed on it,
81 if (!objp
|| !virt_addr_valid(objp
))
84 page
= virt_to_head_page(objp
);
87 * If the allocator sets PageSlab, we know the pointer came from
94 * If it's not a compound page, see if we have a matching VMA
95 * region. This test is intentionally done in reverse order,
96 * so if there's no VMA, we still fall through and hand back
97 * PAGE_SIZE for 0-order pages.
99 if (!PageCompound(page
)) {
100 struct vm_area_struct
*vma
;
102 vma
= find_vma(current
->mm
, (unsigned long)objp
);
104 return vma
->vm_end
- vma
->vm_start
;
108 * The ksize() function is only guaranteed to work for pointers
109 * returned by kmalloc(). So handle arbitrary pointers here.
111 return page_size(page
);
115 * follow_pfn - look up PFN at a user virtual address
116 * @vma: memory mapping
117 * @address: user virtual address
118 * @pfn: location to store found PFN
120 * Only IO mappings and raw PFN mappings are allowed.
122 * Returns zero and the pfn at @pfn on success, -ve otherwise.
124 int follow_pfn(struct vm_area_struct
*vma
, unsigned long address
,
127 if (!(vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)))
130 *pfn
= address
>> PAGE_SHIFT
;
133 EXPORT_SYMBOL(follow_pfn
);
135 LIST_HEAD(vmap_area_list
);
137 void vfree(const void *addr
)
141 EXPORT_SYMBOL(vfree
);
143 void *__vmalloc(unsigned long size
, gfp_t gfp_mask
)
146 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
147 * returns only a logical address.
149 return kmalloc(size
, (gfp_mask
| __GFP_COMP
) & ~__GFP_HIGHMEM
);
151 EXPORT_SYMBOL(__vmalloc
);
153 void *__vmalloc_node_range(unsigned long size
, unsigned long align
,
154 unsigned long start
, unsigned long end
, gfp_t gfp_mask
,
155 pgprot_t prot
, unsigned long vm_flags
, int node
,
158 return __vmalloc(size
, gfp_mask
);
161 void *__vmalloc_node(unsigned long size
, unsigned long align
, gfp_t gfp_mask
,
162 int node
, const void *caller
)
164 return __vmalloc(size
, gfp_mask
);
167 static void *__vmalloc_user_flags(unsigned long size
, gfp_t flags
)
171 ret
= __vmalloc(size
, flags
);
173 struct vm_area_struct
*vma
;
175 mmap_write_lock(current
->mm
);
176 vma
= find_vma(current
->mm
, (unsigned long)ret
);
178 vma
->vm_flags
|= VM_USERMAP
;
179 mmap_write_unlock(current
->mm
);
185 void *vmalloc_user(unsigned long size
)
187 return __vmalloc_user_flags(size
, GFP_KERNEL
| __GFP_ZERO
);
189 EXPORT_SYMBOL(vmalloc_user
);
191 struct page
*vmalloc_to_page(const void *addr
)
193 return virt_to_page(addr
);
195 EXPORT_SYMBOL(vmalloc_to_page
);
197 unsigned long vmalloc_to_pfn(const void *addr
)
199 return page_to_pfn(virt_to_page(addr
));
201 EXPORT_SYMBOL(vmalloc_to_pfn
);
203 long vread(char *buf
, char *addr
, unsigned long count
)
205 /* Don't allow overflow */
206 if ((unsigned long) buf
+ count
< count
)
207 count
= -(unsigned long) buf
;
209 memcpy(buf
, addr
, count
);
214 * vmalloc - allocate virtually contiguous memory
216 * @size: allocation size
218 * Allocate enough pages to cover @size from the page level
219 * allocator and map them into contiguous kernel virtual space.
221 * For tight control over page level allocator and protection flags
222 * use __vmalloc() instead.
224 void *vmalloc(unsigned long size
)
226 return __vmalloc(size
, GFP_KERNEL
);
228 EXPORT_SYMBOL(vmalloc
);
231 * vzalloc - allocate virtually contiguous memory with zero fill
233 * @size: allocation size
235 * Allocate enough pages to cover @size from the page level
236 * allocator and map them into contiguous kernel virtual space.
237 * The memory allocated is set to zero.
239 * For tight control over page level allocator and protection flags
240 * use __vmalloc() instead.
242 void *vzalloc(unsigned long size
)
244 return __vmalloc(size
, GFP_KERNEL
| __GFP_ZERO
);
246 EXPORT_SYMBOL(vzalloc
);
249 * vmalloc_node - allocate memory on a specific node
250 * @size: allocation size
253 * Allocate enough pages to cover @size from the page level
254 * allocator and map them into contiguous kernel virtual space.
256 * For tight control over page level allocator and protection flags
257 * use __vmalloc() instead.
259 void *vmalloc_node(unsigned long size
, int node
)
261 return vmalloc(size
);
263 EXPORT_SYMBOL(vmalloc_node
);
266 * vzalloc_node - allocate memory on a specific node with zero fill
267 * @size: allocation size
270 * Allocate enough pages to cover @size from the page level
271 * allocator and map them into contiguous kernel virtual space.
272 * The memory allocated is set to zero.
274 * For tight control over page level allocator and protection flags
275 * use __vmalloc() instead.
277 void *vzalloc_node(unsigned long size
, int node
)
279 return vzalloc(size
);
281 EXPORT_SYMBOL(vzalloc_node
);
284 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
285 * @size: allocation size
287 * Allocate enough 32bit PA addressable pages to cover @size from the
288 * page level allocator and map them into contiguous kernel virtual space.
290 void *vmalloc_32(unsigned long size
)
292 return __vmalloc(size
, GFP_KERNEL
);
294 EXPORT_SYMBOL(vmalloc_32
);
297 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
298 * @size: allocation size
300 * The resulting memory area is 32bit addressable and zeroed so it can be
301 * mapped to userspace without leaking data.
303 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
304 * remap_vmalloc_range() are permissible.
306 void *vmalloc_32_user(unsigned long size
)
309 * We'll have to sort out the ZONE_DMA bits for 64-bit,
310 * but for now this can simply use vmalloc_user() directly.
312 return vmalloc_user(size
);
314 EXPORT_SYMBOL(vmalloc_32_user
);
316 void *vmap(struct page
**pages
, unsigned int count
, unsigned long flags
, pgprot_t prot
)
323 void vunmap(const void *addr
)
327 EXPORT_SYMBOL(vunmap
);
329 void *vm_map_ram(struct page
**pages
, unsigned int count
, int node
)
334 EXPORT_SYMBOL(vm_map_ram
);
336 void vm_unmap_ram(const void *mem
, unsigned int count
)
340 EXPORT_SYMBOL(vm_unmap_ram
);
342 void vm_unmap_aliases(void)
345 EXPORT_SYMBOL_GPL(vm_unmap_aliases
);
347 void free_vm_area(struct vm_struct
*area
)
351 EXPORT_SYMBOL_GPL(free_vm_area
);
353 int vm_insert_page(struct vm_area_struct
*vma
, unsigned long addr
,
358 EXPORT_SYMBOL(vm_insert_page
);
360 int vm_map_pages(struct vm_area_struct
*vma
, struct page
**pages
,
365 EXPORT_SYMBOL(vm_map_pages
);
367 int vm_map_pages_zero(struct vm_area_struct
*vma
, struct page
**pages
,
372 EXPORT_SYMBOL(vm_map_pages_zero
);
375 * sys_brk() for the most part doesn't need the global kernel
376 * lock, except when an application is doing something nasty
377 * like trying to un-brk an area that has already been mapped
378 * to a regular file. in this case, the unmapping will need
379 * to invoke file system routines that need the global lock.
381 SYSCALL_DEFINE1(brk
, unsigned long, brk
)
383 struct mm_struct
*mm
= current
->mm
;
385 if (brk
< mm
->start_brk
|| brk
> mm
->context
.end_brk
)
392 * Always allow shrinking brk
394 if (brk
<= mm
->brk
) {
400 * Ok, looks good - let it rip.
402 flush_icache_user_range(mm
->brk
, brk
);
403 return mm
->brk
= brk
;
407 * initialise the percpu counter for VM and region record slabs
409 void __init
mmap_init(void)
413 ret
= percpu_counter_init(&vm_committed_as
, 0, GFP_KERNEL
);
415 vm_region_jar
= KMEM_CACHE(vm_region
, SLAB_PANIC
|SLAB_ACCOUNT
);
419 * validate the region tree
420 * - the caller must hold the region lock
422 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
423 static noinline
void validate_nommu_regions(void)
425 struct vm_region
*region
, *last
;
426 struct rb_node
*p
, *lastp
;
428 lastp
= rb_first(&nommu_region_tree
);
432 last
= rb_entry(lastp
, struct vm_region
, vm_rb
);
433 BUG_ON(last
->vm_end
<= last
->vm_start
);
434 BUG_ON(last
->vm_top
< last
->vm_end
);
436 while ((p
= rb_next(lastp
))) {
437 region
= rb_entry(p
, struct vm_region
, vm_rb
);
438 last
= rb_entry(lastp
, struct vm_region
, vm_rb
);
440 BUG_ON(region
->vm_end
<= region
->vm_start
);
441 BUG_ON(region
->vm_top
< region
->vm_end
);
442 BUG_ON(region
->vm_start
< last
->vm_top
);
448 static void validate_nommu_regions(void)
454 * add a region into the global tree
456 static void add_nommu_region(struct vm_region
*region
)
458 struct vm_region
*pregion
;
459 struct rb_node
**p
, *parent
;
461 validate_nommu_regions();
464 p
= &nommu_region_tree
.rb_node
;
467 pregion
= rb_entry(parent
, struct vm_region
, vm_rb
);
468 if (region
->vm_start
< pregion
->vm_start
)
470 else if (region
->vm_start
> pregion
->vm_start
)
472 else if (pregion
== region
)
478 rb_link_node(®ion
->vm_rb
, parent
, p
);
479 rb_insert_color(®ion
->vm_rb
, &nommu_region_tree
);
481 validate_nommu_regions();
485 * delete a region from the global tree
487 static void delete_nommu_region(struct vm_region
*region
)
489 BUG_ON(!nommu_region_tree
.rb_node
);
491 validate_nommu_regions();
492 rb_erase(®ion
->vm_rb
, &nommu_region_tree
);
493 validate_nommu_regions();
497 * free a contiguous series of pages
499 static void free_page_series(unsigned long from
, unsigned long to
)
501 for (; from
< to
; from
+= PAGE_SIZE
) {
502 struct page
*page
= virt_to_page(from
);
504 atomic_long_dec(&mmap_pages_allocated
);
510 * release a reference to a region
511 * - the caller must hold the region semaphore for writing, which this releases
512 * - the region may not have been added to the tree yet, in which case vm_top
513 * will equal vm_start
515 static void __put_nommu_region(struct vm_region
*region
)
516 __releases(nommu_region_sem
)
518 BUG_ON(!nommu_region_tree
.rb_node
);
520 if (--region
->vm_usage
== 0) {
521 if (region
->vm_top
> region
->vm_start
)
522 delete_nommu_region(region
);
523 up_write(&nommu_region_sem
);
526 fput(region
->vm_file
);
528 /* IO memory and memory shared directly out of the pagecache
529 * from ramfs/tmpfs mustn't be released here */
530 if (region
->vm_flags
& VM_MAPPED_COPY
)
531 free_page_series(region
->vm_start
, region
->vm_top
);
532 kmem_cache_free(vm_region_jar
, region
);
534 up_write(&nommu_region_sem
);
539 * release a reference to a region
541 static void put_nommu_region(struct vm_region
*region
)
543 down_write(&nommu_region_sem
);
544 __put_nommu_region(region
);
548 * add a VMA into a process's mm_struct in the appropriate place in the list
549 * and tree and add to the address space's page tree also if not an anonymous
551 * - should be called with mm->mmap_lock held writelocked
553 static void add_vma_to_mm(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
555 struct vm_area_struct
*pvma
, *prev
;
556 struct address_space
*mapping
;
557 struct rb_node
**p
, *parent
, *rb_prev
;
559 BUG_ON(!vma
->vm_region
);
564 /* add the VMA to the mapping */
566 mapping
= vma
->vm_file
->f_mapping
;
568 i_mmap_lock_write(mapping
);
569 flush_dcache_mmap_lock(mapping
);
570 vma_interval_tree_insert(vma
, &mapping
->i_mmap
);
571 flush_dcache_mmap_unlock(mapping
);
572 i_mmap_unlock_write(mapping
);
575 /* add the VMA to the tree */
576 parent
= rb_prev
= NULL
;
577 p
= &mm
->mm_rb
.rb_node
;
580 pvma
= rb_entry(parent
, struct vm_area_struct
, vm_rb
);
582 /* sort by: start addr, end addr, VMA struct addr in that order
583 * (the latter is necessary as we may get identical VMAs) */
584 if (vma
->vm_start
< pvma
->vm_start
)
586 else if (vma
->vm_start
> pvma
->vm_start
) {
589 } else if (vma
->vm_end
< pvma
->vm_end
)
591 else if (vma
->vm_end
> pvma
->vm_end
) {
594 } else if (vma
< pvma
)
596 else if (vma
> pvma
) {
603 rb_link_node(&vma
->vm_rb
, parent
, p
);
604 rb_insert_color(&vma
->vm_rb
, &mm
->mm_rb
);
606 /* add VMA to the VMA list also */
609 prev
= rb_entry(rb_prev
, struct vm_area_struct
, vm_rb
);
611 __vma_link_list(mm
, vma
, prev
);
615 * delete a VMA from its owning mm_struct and address space
617 static void delete_vma_from_mm(struct vm_area_struct
*vma
)
620 struct address_space
*mapping
;
621 struct mm_struct
*mm
= vma
->vm_mm
;
622 struct task_struct
*curr
= current
;
625 for (i
= 0; i
< VMACACHE_SIZE
; i
++) {
626 /* if the vma is cached, invalidate the entire cache */
627 if (curr
->vmacache
.vmas
[i
] == vma
) {
628 vmacache_invalidate(mm
);
633 /* remove the VMA from the mapping */
635 mapping
= vma
->vm_file
->f_mapping
;
637 i_mmap_lock_write(mapping
);
638 flush_dcache_mmap_lock(mapping
);
639 vma_interval_tree_remove(vma
, &mapping
->i_mmap
);
640 flush_dcache_mmap_unlock(mapping
);
641 i_mmap_unlock_write(mapping
);
644 /* remove from the MM's tree and list */
645 rb_erase(&vma
->vm_rb
, &mm
->mm_rb
);
647 __vma_unlink_list(mm
, vma
);
651 * destroy a VMA record
653 static void delete_vma(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
655 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
656 vma
->vm_ops
->close(vma
);
659 put_nommu_region(vma
->vm_region
);
664 * look up the first VMA in which addr resides, NULL if none
665 * - should be called with mm->mmap_lock at least held readlocked
667 struct vm_area_struct
*find_vma(struct mm_struct
*mm
, unsigned long addr
)
669 struct vm_area_struct
*vma
;
671 /* check the cache first */
672 vma
= vmacache_find(mm
, addr
);
676 /* trawl the list (there may be multiple mappings in which addr
678 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
679 if (vma
->vm_start
> addr
)
681 if (vma
->vm_end
> addr
) {
682 vmacache_update(addr
, vma
);
689 EXPORT_SYMBOL(find_vma
);
693 * - we don't extend stack VMAs under NOMMU conditions
695 struct vm_area_struct
*find_extend_vma(struct mm_struct
*mm
, unsigned long addr
)
697 return find_vma(mm
, addr
);
701 * expand a stack to a given address
702 * - not supported under NOMMU conditions
704 int expand_stack(struct vm_area_struct
*vma
, unsigned long address
)
710 * look up the first VMA exactly that exactly matches addr
711 * - should be called with mm->mmap_lock at least held readlocked
713 static struct vm_area_struct
*find_vma_exact(struct mm_struct
*mm
,
717 struct vm_area_struct
*vma
;
718 unsigned long end
= addr
+ len
;
720 /* check the cache first */
721 vma
= vmacache_find_exact(mm
, addr
, end
);
725 /* trawl the list (there may be multiple mappings in which addr
727 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
728 if (vma
->vm_start
< addr
)
730 if (vma
->vm_start
> addr
)
732 if (vma
->vm_end
== end
) {
733 vmacache_update(addr
, vma
);
742 * determine whether a mapping should be permitted and, if so, what sort of
743 * mapping we're capable of supporting
745 static int validate_mmap_request(struct file
*file
,
751 unsigned long *_capabilities
)
753 unsigned long capabilities
, rlen
;
756 /* do the simple checks first */
757 if (flags
& MAP_FIXED
)
760 if ((flags
& MAP_TYPE
) != MAP_PRIVATE
&&
761 (flags
& MAP_TYPE
) != MAP_SHARED
)
767 /* Careful about overflows.. */
768 rlen
= PAGE_ALIGN(len
);
769 if (!rlen
|| rlen
> TASK_SIZE
)
772 /* offset overflow? */
773 if ((pgoff
+ (rlen
>> PAGE_SHIFT
)) < pgoff
)
777 /* files must support mmap */
778 if (!file
->f_op
->mmap
)
781 /* work out if what we've got could possibly be shared
782 * - we support chardevs that provide their own "memory"
783 * - we support files/blockdevs that are memory backed
785 if (file
->f_op
->mmap_capabilities
) {
786 capabilities
= file
->f_op
->mmap_capabilities(file
);
788 /* no explicit capabilities set, so assume some
790 switch (file_inode(file
)->i_mode
& S_IFMT
) {
793 capabilities
= NOMMU_MAP_COPY
;
808 /* eliminate any capabilities that we can't support on this
810 if (!file
->f_op
->get_unmapped_area
)
811 capabilities
&= ~NOMMU_MAP_DIRECT
;
812 if (!(file
->f_mode
& FMODE_CAN_READ
))
813 capabilities
&= ~NOMMU_MAP_COPY
;
815 /* The file shall have been opened with read permission. */
816 if (!(file
->f_mode
& FMODE_READ
))
819 if (flags
& MAP_SHARED
) {
820 /* do checks for writing, appending and locking */
821 if ((prot
& PROT_WRITE
) &&
822 !(file
->f_mode
& FMODE_WRITE
))
825 if (IS_APPEND(file_inode(file
)) &&
826 (file
->f_mode
& FMODE_WRITE
))
829 if (!(capabilities
& NOMMU_MAP_DIRECT
))
832 /* we mustn't privatise shared mappings */
833 capabilities
&= ~NOMMU_MAP_COPY
;
835 /* we're going to read the file into private memory we
837 if (!(capabilities
& NOMMU_MAP_COPY
))
840 /* we don't permit a private writable mapping to be
841 * shared with the backing device */
842 if (prot
& PROT_WRITE
)
843 capabilities
&= ~NOMMU_MAP_DIRECT
;
846 if (capabilities
& NOMMU_MAP_DIRECT
) {
847 if (((prot
& PROT_READ
) && !(capabilities
& NOMMU_MAP_READ
)) ||
848 ((prot
& PROT_WRITE
) && !(capabilities
& NOMMU_MAP_WRITE
)) ||
849 ((prot
& PROT_EXEC
) && !(capabilities
& NOMMU_MAP_EXEC
))
851 capabilities
&= ~NOMMU_MAP_DIRECT
;
852 if (flags
& MAP_SHARED
) {
853 pr_warn("MAP_SHARED not completely supported on !MMU\n");
859 /* handle executable mappings and implied executable
861 if (path_noexec(&file
->f_path
)) {
862 if (prot
& PROT_EXEC
)
864 } else if ((prot
& PROT_READ
) && !(prot
& PROT_EXEC
)) {
865 /* handle implication of PROT_EXEC by PROT_READ */
866 if (current
->personality
& READ_IMPLIES_EXEC
) {
867 if (capabilities
& NOMMU_MAP_EXEC
)
870 } else if ((prot
& PROT_READ
) &&
871 (prot
& PROT_EXEC
) &&
872 !(capabilities
& NOMMU_MAP_EXEC
)
874 /* backing file is not executable, try to copy */
875 capabilities
&= ~NOMMU_MAP_DIRECT
;
878 /* anonymous mappings are always memory backed and can be
881 capabilities
= NOMMU_MAP_COPY
;
883 /* handle PROT_EXEC implication by PROT_READ */
884 if ((prot
& PROT_READ
) &&
885 (current
->personality
& READ_IMPLIES_EXEC
))
889 /* allow the security API to have its say */
890 ret
= security_mmap_addr(addr
);
895 *_capabilities
= capabilities
;
900 * we've determined that we can make the mapping, now translate what we
901 * now know into VMA flags
903 static unsigned long determine_vm_flags(struct file
*file
,
906 unsigned long capabilities
)
908 unsigned long vm_flags
;
910 vm_flags
= calc_vm_prot_bits(prot
, 0) | calc_vm_flag_bits(flags
);
911 /* vm_flags |= mm->def_flags; */
913 if (!(capabilities
& NOMMU_MAP_DIRECT
)) {
914 /* attempt to share read-only copies of mapped file chunks */
915 vm_flags
|= VM_MAYREAD
| VM_MAYWRITE
| VM_MAYEXEC
;
916 if (file
&& !(prot
& PROT_WRITE
))
917 vm_flags
|= VM_MAYSHARE
;
919 /* overlay a shareable mapping on the backing device or inode
920 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
922 vm_flags
|= VM_MAYSHARE
| (capabilities
& NOMMU_VMFLAGS
);
923 if (flags
& MAP_SHARED
)
924 vm_flags
|= VM_SHARED
;
927 /* refuse to let anyone share private mappings with this process if
928 * it's being traced - otherwise breakpoints set in it may interfere
929 * with another untraced process
931 if ((flags
& MAP_PRIVATE
) && current
->ptrace
)
932 vm_flags
&= ~VM_MAYSHARE
;
938 * set up a shared mapping on a file (the driver or filesystem provides and
941 static int do_mmap_shared_file(struct vm_area_struct
*vma
)
945 ret
= call_mmap(vma
->vm_file
, vma
);
947 vma
->vm_region
->vm_top
= vma
->vm_region
->vm_end
;
953 /* getting -ENOSYS indicates that direct mmap isn't possible (as
954 * opposed to tried but failed) so we can only give a suitable error as
955 * it's not possible to make a private copy if MAP_SHARED was given */
960 * set up a private mapping or an anonymous shared mapping
962 static int do_mmap_private(struct vm_area_struct
*vma
,
963 struct vm_region
*region
,
965 unsigned long capabilities
)
967 unsigned long total
, point
;
971 /* invoke the file's mapping function so that it can keep track of
972 * shared mappings on devices or memory
973 * - VM_MAYSHARE will be set if it may attempt to share
975 if (capabilities
& NOMMU_MAP_DIRECT
) {
976 ret
= call_mmap(vma
->vm_file
, vma
);
978 /* shouldn't return success if we're not sharing */
979 BUG_ON(!(vma
->vm_flags
& VM_MAYSHARE
));
980 vma
->vm_region
->vm_top
= vma
->vm_region
->vm_end
;
986 /* getting an ENOSYS error indicates that direct mmap isn't
987 * possible (as opposed to tried but failed) so we'll try to
988 * make a private copy of the data and map that instead */
992 /* allocate some memory to hold the mapping
993 * - note that this may not return a page-aligned address if the object
994 * we're allocating is smaller than a page
996 order
= get_order(len
);
998 point
= len
>> PAGE_SHIFT
;
1000 /* we don't want to allocate a power-of-2 sized page set */
1001 if (sysctl_nr_trim_pages
&& total
- point
>= sysctl_nr_trim_pages
)
1004 base
= alloc_pages_exact(total
<< PAGE_SHIFT
, GFP_KERNEL
);
1008 atomic_long_add(total
, &mmap_pages_allocated
);
1010 region
->vm_flags
= vma
->vm_flags
|= VM_MAPPED_COPY
;
1011 region
->vm_start
= (unsigned long) base
;
1012 region
->vm_end
= region
->vm_start
+ len
;
1013 region
->vm_top
= region
->vm_start
+ (total
<< PAGE_SHIFT
);
1015 vma
->vm_start
= region
->vm_start
;
1016 vma
->vm_end
= region
->vm_start
+ len
;
1019 /* read the contents of a file into the copy */
1022 fpos
= vma
->vm_pgoff
;
1023 fpos
<<= PAGE_SHIFT
;
1025 ret
= kernel_read(vma
->vm_file
, base
, len
, &fpos
);
1029 /* clear the last little bit */
1031 memset(base
+ ret
, 0, len
- ret
);
1034 vma_set_anonymous(vma
);
1040 free_page_series(region
->vm_start
, region
->vm_top
);
1041 region
->vm_start
= vma
->vm_start
= 0;
1042 region
->vm_end
= vma
->vm_end
= 0;
1047 pr_err("Allocation of length %lu from process %d (%s) failed\n",
1048 len
, current
->pid
, current
->comm
);
1049 show_free_areas(0, NULL
);
1054 * handle mapping creation for uClinux
1056 unsigned long do_mmap(struct file
*file
,
1060 unsigned long flags
,
1061 unsigned long pgoff
,
1062 unsigned long *populate
,
1063 struct list_head
*uf
)
1065 struct vm_area_struct
*vma
;
1066 struct vm_region
*region
;
1068 vm_flags_t vm_flags
;
1069 unsigned long capabilities
, result
;
1074 /* decide whether we should attempt the mapping, and if so what sort of
1076 ret
= validate_mmap_request(file
, addr
, len
, prot
, flags
, pgoff
,
1081 /* we ignore the address hint */
1083 len
= PAGE_ALIGN(len
);
1085 /* we've determined that we can make the mapping, now translate what we
1086 * now know into VMA flags */
1087 vm_flags
= determine_vm_flags(file
, prot
, flags
, capabilities
);
1089 /* we're going to need to record the mapping */
1090 region
= kmem_cache_zalloc(vm_region_jar
, GFP_KERNEL
);
1092 goto error_getting_region
;
1094 vma
= vm_area_alloc(current
->mm
);
1096 goto error_getting_vma
;
1098 region
->vm_usage
= 1;
1099 region
->vm_flags
= vm_flags
;
1100 region
->vm_pgoff
= pgoff
;
1102 vma
->vm_flags
= vm_flags
;
1103 vma
->vm_pgoff
= pgoff
;
1106 region
->vm_file
= get_file(file
);
1107 vma
->vm_file
= get_file(file
);
1110 down_write(&nommu_region_sem
);
1112 /* if we want to share, we need to check for regions created by other
1113 * mmap() calls that overlap with our proposed mapping
1114 * - we can only share with a superset match on most regular files
1115 * - shared mappings on character devices and memory backed files are
1116 * permitted to overlap inexactly as far as we are concerned for in
1117 * these cases, sharing is handled in the driver or filesystem rather
1120 if (vm_flags
& VM_MAYSHARE
) {
1121 struct vm_region
*pregion
;
1122 unsigned long pglen
, rpglen
, pgend
, rpgend
, start
;
1124 pglen
= (len
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1125 pgend
= pgoff
+ pglen
;
1127 for (rb
= rb_first(&nommu_region_tree
); rb
; rb
= rb_next(rb
)) {
1128 pregion
= rb_entry(rb
, struct vm_region
, vm_rb
);
1130 if (!(pregion
->vm_flags
& VM_MAYSHARE
))
1133 /* search for overlapping mappings on the same file */
1134 if (file_inode(pregion
->vm_file
) !=
1138 if (pregion
->vm_pgoff
>= pgend
)
1141 rpglen
= pregion
->vm_end
- pregion
->vm_start
;
1142 rpglen
= (rpglen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1143 rpgend
= pregion
->vm_pgoff
+ rpglen
;
1144 if (pgoff
>= rpgend
)
1147 /* handle inexactly overlapping matches between
1149 if ((pregion
->vm_pgoff
!= pgoff
|| rpglen
!= pglen
) &&
1150 !(pgoff
>= pregion
->vm_pgoff
&& pgend
<= rpgend
)) {
1151 /* new mapping is not a subset of the region */
1152 if (!(capabilities
& NOMMU_MAP_DIRECT
))
1153 goto sharing_violation
;
1157 /* we've found a region we can share */
1158 pregion
->vm_usage
++;
1159 vma
->vm_region
= pregion
;
1160 start
= pregion
->vm_start
;
1161 start
+= (pgoff
- pregion
->vm_pgoff
) << PAGE_SHIFT
;
1162 vma
->vm_start
= start
;
1163 vma
->vm_end
= start
+ len
;
1165 if (pregion
->vm_flags
& VM_MAPPED_COPY
)
1166 vma
->vm_flags
|= VM_MAPPED_COPY
;
1168 ret
= do_mmap_shared_file(vma
);
1170 vma
->vm_region
= NULL
;
1173 pregion
->vm_usage
--;
1175 goto error_just_free
;
1178 fput(region
->vm_file
);
1179 kmem_cache_free(vm_region_jar
, region
);
1185 /* obtain the address at which to make a shared mapping
1186 * - this is the hook for quasi-memory character devices to
1187 * tell us the location of a shared mapping
1189 if (capabilities
& NOMMU_MAP_DIRECT
) {
1190 addr
= file
->f_op
->get_unmapped_area(file
, addr
, len
,
1192 if (IS_ERR_VALUE(addr
)) {
1195 goto error_just_free
;
1197 /* the driver refused to tell us where to site
1198 * the mapping so we'll have to attempt to copy
1201 if (!(capabilities
& NOMMU_MAP_COPY
))
1202 goto error_just_free
;
1204 capabilities
&= ~NOMMU_MAP_DIRECT
;
1206 vma
->vm_start
= region
->vm_start
= addr
;
1207 vma
->vm_end
= region
->vm_end
= addr
+ len
;
1212 vma
->vm_region
= region
;
1214 /* set up the mapping
1215 * - the region is filled in if NOMMU_MAP_DIRECT is still set
1217 if (file
&& vma
->vm_flags
& VM_SHARED
)
1218 ret
= do_mmap_shared_file(vma
);
1220 ret
= do_mmap_private(vma
, region
, len
, capabilities
);
1222 goto error_just_free
;
1223 add_nommu_region(region
);
1225 /* clear anonymous mappings that don't ask for uninitialized data */
1226 if (!vma
->vm_file
&&
1227 (!IS_ENABLED(CONFIG_MMAP_ALLOW_UNINITIALIZED
) ||
1228 !(flags
& MAP_UNINITIALIZED
)))
1229 memset((void *)region
->vm_start
, 0,
1230 region
->vm_end
- region
->vm_start
);
1232 /* okay... we have a mapping; now we have to register it */
1233 result
= vma
->vm_start
;
1235 current
->mm
->total_vm
+= len
>> PAGE_SHIFT
;
1238 add_vma_to_mm(current
->mm
, vma
);
1240 /* we flush the region from the icache only when the first executable
1241 * mapping of it is made */
1242 if (vma
->vm_flags
& VM_EXEC
&& !region
->vm_icache_flushed
) {
1243 flush_icache_user_range(region
->vm_start
, region
->vm_end
);
1244 region
->vm_icache_flushed
= true;
1247 up_write(&nommu_region_sem
);
1252 up_write(&nommu_region_sem
);
1254 if (region
->vm_file
)
1255 fput(region
->vm_file
);
1256 kmem_cache_free(vm_region_jar
, region
);
1263 up_write(&nommu_region_sem
);
1264 pr_warn("Attempt to share mismatched mappings\n");
1269 kmem_cache_free(vm_region_jar
, region
);
1270 pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n",
1272 show_free_areas(0, NULL
);
1275 error_getting_region
:
1276 pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n",
1278 show_free_areas(0, NULL
);
1282 unsigned long ksys_mmap_pgoff(unsigned long addr
, unsigned long len
,
1283 unsigned long prot
, unsigned long flags
,
1284 unsigned long fd
, unsigned long pgoff
)
1286 struct file
*file
= NULL
;
1287 unsigned long retval
= -EBADF
;
1289 audit_mmap_fd(fd
, flags
);
1290 if (!(flags
& MAP_ANONYMOUS
)) {
1296 retval
= vm_mmap_pgoff(file
, addr
, len
, prot
, flags
, pgoff
);
1304 SYSCALL_DEFINE6(mmap_pgoff
, unsigned long, addr
, unsigned long, len
,
1305 unsigned long, prot
, unsigned long, flags
,
1306 unsigned long, fd
, unsigned long, pgoff
)
1308 return ksys_mmap_pgoff(addr
, len
, prot
, flags
, fd
, pgoff
);
1311 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1312 struct mmap_arg_struct
{
1316 unsigned long flags
;
1318 unsigned long offset
;
1321 SYSCALL_DEFINE1(old_mmap
, struct mmap_arg_struct __user
*, arg
)
1323 struct mmap_arg_struct a
;
1325 if (copy_from_user(&a
, arg
, sizeof(a
)))
1327 if (offset_in_page(a
.offset
))
1330 return ksys_mmap_pgoff(a
.addr
, a
.len
, a
.prot
, a
.flags
, a
.fd
,
1331 a
.offset
>> PAGE_SHIFT
);
1333 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1336 * split a vma into two pieces at address 'addr', a new vma is allocated either
1337 * for the first part or the tail.
1339 int split_vma(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1340 unsigned long addr
, int new_below
)
1342 struct vm_area_struct
*new;
1343 struct vm_region
*region
;
1344 unsigned long npages
;
1346 /* we're only permitted to split anonymous regions (these should have
1347 * only a single usage on the region) */
1351 if (mm
->map_count
>= sysctl_max_map_count
)
1354 region
= kmem_cache_alloc(vm_region_jar
, GFP_KERNEL
);
1358 new = vm_area_dup(vma
);
1360 kmem_cache_free(vm_region_jar
, region
);
1364 /* most fields are the same, copy all, and then fixup */
1365 *region
= *vma
->vm_region
;
1366 new->vm_region
= region
;
1368 npages
= (addr
- vma
->vm_start
) >> PAGE_SHIFT
;
1371 region
->vm_top
= region
->vm_end
= new->vm_end
= addr
;
1373 region
->vm_start
= new->vm_start
= addr
;
1374 region
->vm_pgoff
= new->vm_pgoff
+= npages
;
1377 if (new->vm_ops
&& new->vm_ops
->open
)
1378 new->vm_ops
->open(new);
1380 delete_vma_from_mm(vma
);
1381 down_write(&nommu_region_sem
);
1382 delete_nommu_region(vma
->vm_region
);
1384 vma
->vm_region
->vm_start
= vma
->vm_start
= addr
;
1385 vma
->vm_region
->vm_pgoff
= vma
->vm_pgoff
+= npages
;
1387 vma
->vm_region
->vm_end
= vma
->vm_end
= addr
;
1388 vma
->vm_region
->vm_top
= addr
;
1390 add_nommu_region(vma
->vm_region
);
1391 add_nommu_region(new->vm_region
);
1392 up_write(&nommu_region_sem
);
1393 add_vma_to_mm(mm
, vma
);
1394 add_vma_to_mm(mm
, new);
1399 * shrink a VMA by removing the specified chunk from either the beginning or
1402 static int shrink_vma(struct mm_struct
*mm
,
1403 struct vm_area_struct
*vma
,
1404 unsigned long from
, unsigned long to
)
1406 struct vm_region
*region
;
1408 /* adjust the VMA's pointers, which may reposition it in the MM's tree
1410 delete_vma_from_mm(vma
);
1411 if (from
> vma
->vm_start
)
1415 add_vma_to_mm(mm
, vma
);
1417 /* cut the backing region down to size */
1418 region
= vma
->vm_region
;
1419 BUG_ON(region
->vm_usage
!= 1);
1421 down_write(&nommu_region_sem
);
1422 delete_nommu_region(region
);
1423 if (from
> region
->vm_start
) {
1424 to
= region
->vm_top
;
1425 region
->vm_top
= region
->vm_end
= from
;
1427 region
->vm_start
= to
;
1429 add_nommu_region(region
);
1430 up_write(&nommu_region_sem
);
1432 free_page_series(from
, to
);
1438 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1439 * VMA, though it need not cover the whole VMA
1441 int do_munmap(struct mm_struct
*mm
, unsigned long start
, size_t len
, struct list_head
*uf
)
1443 struct vm_area_struct
*vma
;
1447 len
= PAGE_ALIGN(len
);
1453 /* find the first potentially overlapping VMA */
1454 vma
= find_vma(mm
, start
);
1458 pr_warn("munmap of memory not mmapped by process %d (%s): 0x%lx-0x%lx\n",
1459 current
->pid
, current
->comm
,
1460 start
, start
+ len
- 1);
1466 /* we're allowed to split an anonymous VMA but not a file-backed one */
1469 if (start
> vma
->vm_start
)
1471 if (end
== vma
->vm_end
)
1472 goto erase_whole_vma
;
1477 /* the chunk must be a subset of the VMA found */
1478 if (start
== vma
->vm_start
&& end
== vma
->vm_end
)
1479 goto erase_whole_vma
;
1480 if (start
< vma
->vm_start
|| end
> vma
->vm_end
)
1482 if (offset_in_page(start
))
1484 if (end
!= vma
->vm_end
&& offset_in_page(end
))
1486 if (start
!= vma
->vm_start
&& end
!= vma
->vm_end
) {
1487 ret
= split_vma(mm
, vma
, start
, 1);
1491 return shrink_vma(mm
, vma
, start
, end
);
1495 delete_vma_from_mm(vma
);
1496 delete_vma(mm
, vma
);
1500 int vm_munmap(unsigned long addr
, size_t len
)
1502 struct mm_struct
*mm
= current
->mm
;
1505 mmap_write_lock(mm
);
1506 ret
= do_munmap(mm
, addr
, len
, NULL
);
1507 mmap_write_unlock(mm
);
1510 EXPORT_SYMBOL(vm_munmap
);
1512 SYSCALL_DEFINE2(munmap
, unsigned long, addr
, size_t, len
)
1514 return vm_munmap(addr
, len
);
1518 * release all the mappings made in a process's VM space
1520 void exit_mmap(struct mm_struct
*mm
)
1522 struct vm_area_struct
*vma
;
1529 while ((vma
= mm
->mmap
)) {
1530 mm
->mmap
= vma
->vm_next
;
1531 delete_vma_from_mm(vma
);
1532 delete_vma(mm
, vma
);
1537 int vm_brk(unsigned long addr
, unsigned long len
)
1543 * expand (or shrink) an existing mapping, potentially moving it at the same
1544 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1546 * under NOMMU conditions, we only permit changing a mapping's size, and only
1547 * as long as it stays within the region allocated by do_mmap_private() and the
1548 * block is not shareable
1550 * MREMAP_FIXED is not supported under NOMMU conditions
1552 static unsigned long do_mremap(unsigned long addr
,
1553 unsigned long old_len
, unsigned long new_len
,
1554 unsigned long flags
, unsigned long new_addr
)
1556 struct vm_area_struct
*vma
;
1558 /* insanity checks first */
1559 old_len
= PAGE_ALIGN(old_len
);
1560 new_len
= PAGE_ALIGN(new_len
);
1561 if (old_len
== 0 || new_len
== 0)
1562 return (unsigned long) -EINVAL
;
1564 if (offset_in_page(addr
))
1567 if (flags
& MREMAP_FIXED
&& new_addr
!= addr
)
1568 return (unsigned long) -EINVAL
;
1570 vma
= find_vma_exact(current
->mm
, addr
, old_len
);
1572 return (unsigned long) -EINVAL
;
1574 if (vma
->vm_end
!= vma
->vm_start
+ old_len
)
1575 return (unsigned long) -EFAULT
;
1577 if (vma
->vm_flags
& VM_MAYSHARE
)
1578 return (unsigned long) -EPERM
;
1580 if (new_len
> vma
->vm_region
->vm_end
- vma
->vm_region
->vm_start
)
1581 return (unsigned long) -ENOMEM
;
1583 /* all checks complete - do it */
1584 vma
->vm_end
= vma
->vm_start
+ new_len
;
1585 return vma
->vm_start
;
1588 SYSCALL_DEFINE5(mremap
, unsigned long, addr
, unsigned long, old_len
,
1589 unsigned long, new_len
, unsigned long, flags
,
1590 unsigned long, new_addr
)
1594 mmap_write_lock(current
->mm
);
1595 ret
= do_mremap(addr
, old_len
, new_len
, flags
, new_addr
);
1596 mmap_write_unlock(current
->mm
);
1600 struct page
*follow_page(struct vm_area_struct
*vma
, unsigned long address
,
1601 unsigned int foll_flags
)
1606 int remap_pfn_range(struct vm_area_struct
*vma
, unsigned long addr
,
1607 unsigned long pfn
, unsigned long size
, pgprot_t prot
)
1609 if (addr
!= (pfn
<< PAGE_SHIFT
))
1612 vma
->vm_flags
|= VM_IO
| VM_PFNMAP
| VM_DONTEXPAND
| VM_DONTDUMP
;
1615 EXPORT_SYMBOL(remap_pfn_range
);
1617 int vm_iomap_memory(struct vm_area_struct
*vma
, phys_addr_t start
, unsigned long len
)
1619 unsigned long pfn
= start
>> PAGE_SHIFT
;
1620 unsigned long vm_len
= vma
->vm_end
- vma
->vm_start
;
1622 pfn
+= vma
->vm_pgoff
;
1623 return io_remap_pfn_range(vma
, vma
->vm_start
, pfn
, vm_len
, vma
->vm_page_prot
);
1625 EXPORT_SYMBOL(vm_iomap_memory
);
1627 int remap_vmalloc_range(struct vm_area_struct
*vma
, void *addr
,
1628 unsigned long pgoff
)
1630 unsigned int size
= vma
->vm_end
- vma
->vm_start
;
1632 if (!(vma
->vm_flags
& VM_USERMAP
))
1635 vma
->vm_start
= (unsigned long)(addr
+ (pgoff
<< PAGE_SHIFT
));
1636 vma
->vm_end
= vma
->vm_start
+ size
;
1640 EXPORT_SYMBOL(remap_vmalloc_range
);
1642 unsigned long arch_get_unmapped_area(struct file
*file
, unsigned long addr
,
1643 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
1648 vm_fault_t
filemap_fault(struct vm_fault
*vmf
)
1653 EXPORT_SYMBOL(filemap_fault
);
1655 vm_fault_t
filemap_map_pages(struct vm_fault
*vmf
,
1656 pgoff_t start_pgoff
, pgoff_t end_pgoff
)
1661 EXPORT_SYMBOL(filemap_map_pages
);
1663 int __access_remote_vm(struct mm_struct
*mm
, unsigned long addr
, void *buf
,
1664 int len
, unsigned int gup_flags
)
1666 struct vm_area_struct
*vma
;
1667 int write
= gup_flags
& FOLL_WRITE
;
1669 if (mmap_read_lock_killable(mm
))
1672 /* the access must start within one of the target process's mappings */
1673 vma
= find_vma(mm
, addr
);
1675 /* don't overrun this mapping */
1676 if (addr
+ len
>= vma
->vm_end
)
1677 len
= vma
->vm_end
- addr
;
1679 /* only read or write mappings where it is permitted */
1680 if (write
&& vma
->vm_flags
& VM_MAYWRITE
)
1681 copy_to_user_page(vma
, NULL
, addr
,
1682 (void *) addr
, buf
, len
);
1683 else if (!write
&& vma
->vm_flags
& VM_MAYREAD
)
1684 copy_from_user_page(vma
, NULL
, addr
,
1685 buf
, (void *) addr
, len
);
1692 mmap_read_unlock(mm
);
1698 * access_remote_vm - access another process' address space
1699 * @mm: the mm_struct of the target address space
1700 * @addr: start address to access
1701 * @buf: source or destination buffer
1702 * @len: number of bytes to transfer
1703 * @gup_flags: flags modifying lookup behaviour
1705 * The caller must hold a reference on @mm.
1707 int access_remote_vm(struct mm_struct
*mm
, unsigned long addr
,
1708 void *buf
, int len
, unsigned int gup_flags
)
1710 return __access_remote_vm(mm
, addr
, buf
, len
, gup_flags
);
1714 * Access another process' address space.
1715 * - source/target buffer must be kernel space
1717 int access_process_vm(struct task_struct
*tsk
, unsigned long addr
, void *buf
, int len
,
1718 unsigned int gup_flags
)
1720 struct mm_struct
*mm
;
1722 if (addr
+ len
< addr
)
1725 mm
= get_task_mm(tsk
);
1729 len
= __access_remote_vm(mm
, addr
, buf
, len
, gup_flags
);
1734 EXPORT_SYMBOL_GPL(access_process_vm
);
1737 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
1738 * @inode: The inode to check
1739 * @size: The current filesize of the inode
1740 * @newsize: The proposed filesize of the inode
1742 * Check the shared mappings on an inode on behalf of a shrinking truncate to
1743 * make sure that any outstanding VMAs aren't broken and then shrink the
1744 * vm_regions that extend beyond so that do_mmap() doesn't
1745 * automatically grant mappings that are too large.
1747 int nommu_shrink_inode_mappings(struct inode
*inode
, size_t size
,
1750 struct vm_area_struct
*vma
;
1751 struct vm_region
*region
;
1753 size_t r_size
, r_top
;
1755 low
= newsize
>> PAGE_SHIFT
;
1756 high
= (size
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1758 down_write(&nommu_region_sem
);
1759 i_mmap_lock_read(inode
->i_mapping
);
1761 /* search for VMAs that fall within the dead zone */
1762 vma_interval_tree_foreach(vma
, &inode
->i_mapping
->i_mmap
, low
, high
) {
1763 /* found one - only interested if it's shared out of the page
1765 if (vma
->vm_flags
& VM_SHARED
) {
1766 i_mmap_unlock_read(inode
->i_mapping
);
1767 up_write(&nommu_region_sem
);
1768 return -ETXTBSY
; /* not quite true, but near enough */
1772 /* reduce any regions that overlap the dead zone - if in existence,
1773 * these will be pointed to by VMAs that don't overlap the dead zone
1775 * we don't check for any regions that start beyond the EOF as there
1778 vma_interval_tree_foreach(vma
, &inode
->i_mapping
->i_mmap
, 0, ULONG_MAX
) {
1779 if (!(vma
->vm_flags
& VM_SHARED
))
1782 region
= vma
->vm_region
;
1783 r_size
= region
->vm_top
- region
->vm_start
;
1784 r_top
= (region
->vm_pgoff
<< PAGE_SHIFT
) + r_size
;
1786 if (r_top
> newsize
) {
1787 region
->vm_top
-= r_top
- newsize
;
1788 if (region
->vm_end
> region
->vm_top
)
1789 region
->vm_end
= region
->vm_top
;
1793 i_mmap_unlock_read(inode
->i_mapping
);
1794 up_write(&nommu_region_sem
);
1799 * Initialise sysctl_user_reserve_kbytes.
1801 * This is intended to prevent a user from starting a single memory hogging
1802 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
1805 * The default value is min(3% of free memory, 128MB)
1806 * 128MB is enough to recover with sshd/login, bash, and top/kill.
1808 static int __meminit
init_user_reserve(void)
1810 unsigned long free_kbytes
;
1812 free_kbytes
= global_zone_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
1814 sysctl_user_reserve_kbytes
= min(free_kbytes
/ 32, 1UL << 17);
1817 subsys_initcall(init_user_reserve
);
1820 * Initialise sysctl_admin_reserve_kbytes.
1822 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
1823 * to log in and kill a memory hogging process.
1825 * Systems with more than 256MB will reserve 8MB, enough to recover
1826 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
1827 * only reserve 3% of free pages by default.
1829 static int __meminit
init_admin_reserve(void)
1831 unsigned long free_kbytes
;
1833 free_kbytes
= global_zone_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
1835 sysctl_admin_reserve_kbytes
= min(free_kbytes
/ 32, 1UL << 13);
1838 subsys_initcall(init_admin_reserve
);