mirror of
https://github.com/FEX-Emu/linux.git
synced 2024-12-09 00:47:54 +00:00
ca16d140af
The type of vma->vm_flags is 'unsigned long'. Neither 'int' nor 'unsigned int'. This patch fixes such misuse. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> [ Changed to use a typedef - we'll extend it to cover more cases later, since there has been discussion about making it a 64-bit type.. - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
617 lines
16 KiB
C
617 lines
16 KiB
C
/*
|
|
* linux/mm/mlock.c
|
|
*
|
|
* (C) Copyright 1995 Linus Torvalds
|
|
* (C) Copyright 2002 Christoph Hellwig
|
|
*/
|
|
|
|
#include <linux/capability.h>
|
|
#include <linux/mman.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/swap.h>
|
|
#include <linux/swapops.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/mempolicy.h>
|
|
#include <linux/syscalls.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/module.h>
|
|
#include <linux/rmap.h>
|
|
#include <linux/mmzone.h>
|
|
#include <linux/hugetlb.h>
|
|
|
|
#include "internal.h"
|
|
|
|
int can_do_mlock(void)
|
|
{
|
|
if (capable(CAP_IPC_LOCK))
|
|
return 1;
|
|
if (rlimit(RLIMIT_MEMLOCK) != 0)
|
|
return 1;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(can_do_mlock);
|
|
|
|
/*
|
|
* Mlocked pages are marked with PageMlocked() flag for efficient testing
|
|
* in vmscan and, possibly, the fault path; and to support semi-accurate
|
|
* statistics.
|
|
*
|
|
* An mlocked page [PageMlocked(page)] is unevictable. As such, it will
|
|
* be placed on the LRU "unevictable" list, rather than the [in]active lists.
|
|
* The unevictable list is an LRU sibling list to the [in]active lists.
|
|
* PageUnevictable is set to indicate the unevictable state.
|
|
*
|
|
* When lazy mlocking via vmscan, it is important to ensure that the
|
|
* vma's VM_LOCKED status is not concurrently being modified, otherwise we
|
|
* may have mlocked a page that is being munlocked. So lazy mlock must take
|
|
* the mmap_sem for read, and verify that the vma really is locked
|
|
* (see mm/rmap.c).
|
|
*/
|
|
|
|
/*
|
|
* LRU accounting for clear_page_mlock()
|
|
*/
|
|
void __clear_page_mlock(struct page *page)
|
|
{
|
|
VM_BUG_ON(!PageLocked(page));
|
|
|
|
if (!page->mapping) { /* truncated ? */
|
|
return;
|
|
}
|
|
|
|
dec_zone_page_state(page, NR_MLOCK);
|
|
count_vm_event(UNEVICTABLE_PGCLEARED);
|
|
if (!isolate_lru_page(page)) {
|
|
putback_lru_page(page);
|
|
} else {
|
|
/*
|
|
* We lost the race. the page already moved to evictable list.
|
|
*/
|
|
if (PageUnevictable(page))
|
|
count_vm_event(UNEVICTABLE_PGSTRANDED);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Mark page as mlocked if not already.
|
|
* If page on LRU, isolate and putback to move to unevictable list.
|
|
*/
|
|
void mlock_vma_page(struct page *page)
|
|
{
|
|
BUG_ON(!PageLocked(page));
|
|
|
|
if (!TestSetPageMlocked(page)) {
|
|
inc_zone_page_state(page, NR_MLOCK);
|
|
count_vm_event(UNEVICTABLE_PGMLOCKED);
|
|
if (!isolate_lru_page(page))
|
|
putback_lru_page(page);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* munlock_vma_page - munlock a vma page
|
|
* @page - page to be unlocked
|
|
*
|
|
* called from munlock()/munmap() path with page supposedly on the LRU.
|
|
* When we munlock a page, because the vma where we found the page is being
|
|
* munlock()ed or munmap()ed, we want to check whether other vmas hold the
|
|
* page locked so that we can leave it on the unevictable lru list and not
|
|
* bother vmscan with it. However, to walk the page's rmap list in
|
|
* try_to_munlock() we must isolate the page from the LRU. If some other
|
|
* task has removed the page from the LRU, we won't be able to do that.
|
|
* So we clear the PageMlocked as we might not get another chance. If we
|
|
* can't isolate the page, we leave it for putback_lru_page() and vmscan
|
|
* [page_referenced()/try_to_unmap()] to deal with.
|
|
*/
|
|
void munlock_vma_page(struct page *page)
|
|
{
|
|
BUG_ON(!PageLocked(page));
|
|
|
|
if (TestClearPageMlocked(page)) {
|
|
dec_zone_page_state(page, NR_MLOCK);
|
|
if (!isolate_lru_page(page)) {
|
|
int ret = try_to_munlock(page);
|
|
/*
|
|
* did try_to_unlock() succeed or punt?
|
|
*/
|
|
if (ret != SWAP_MLOCK)
|
|
count_vm_event(UNEVICTABLE_PGMUNLOCKED);
|
|
|
|
putback_lru_page(page);
|
|
} else {
|
|
/*
|
|
* Some other task has removed the page from the LRU.
|
|
* putback_lru_page() will take care of removing the
|
|
* page from the unevictable list, if necessary.
|
|
* vmscan [page_referenced()] will move the page back
|
|
* to the unevictable list if some other vma has it
|
|
* mlocked.
|
|
*/
|
|
if (PageUnevictable(page))
|
|
count_vm_event(UNEVICTABLE_PGSTRANDED);
|
|
else
|
|
count_vm_event(UNEVICTABLE_PGMUNLOCKED);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* __mlock_vma_pages_range() - mlock a range of pages in the vma.
|
|
* @vma: target vma
|
|
* @start: start address
|
|
* @end: end address
|
|
*
|
|
* This takes care of making the pages present too.
|
|
*
|
|
* return 0 on success, negative error code on error.
|
|
*
|
|
* vma->vm_mm->mmap_sem must be held for at least read.
|
|
*/
|
|
static long __mlock_vma_pages_range(struct vm_area_struct *vma,
|
|
unsigned long start, unsigned long end,
|
|
int *nonblocking)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
unsigned long addr = start;
|
|
int nr_pages = (end - start) / PAGE_SIZE;
|
|
int gup_flags;
|
|
|
|
VM_BUG_ON(start & ~PAGE_MASK);
|
|
VM_BUG_ON(end & ~PAGE_MASK);
|
|
VM_BUG_ON(start < vma->vm_start);
|
|
VM_BUG_ON(end > vma->vm_end);
|
|
VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
|
|
|
|
gup_flags = FOLL_TOUCH | FOLL_MLOCK;
|
|
/*
|
|
* We want to touch writable mappings with a write fault in order
|
|
* to break COW, except for shared mappings because these don't COW
|
|
* and we would not want to dirty them for nothing.
|
|
*/
|
|
if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
|
|
gup_flags |= FOLL_WRITE;
|
|
|
|
/*
|
|
* We want mlock to succeed for regions that have any permissions
|
|
* other than PROT_NONE.
|
|
*/
|
|
if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
|
|
gup_flags |= FOLL_FORCE;
|
|
|
|
return __get_user_pages(current, mm, addr, nr_pages, gup_flags,
|
|
NULL, NULL, nonblocking);
|
|
}
|
|
|
|
/*
|
|
* convert get_user_pages() return value to posix mlock() error
|
|
*/
|
|
static int __mlock_posix_error_return(long retval)
|
|
{
|
|
if (retval == -EFAULT)
|
|
retval = -ENOMEM;
|
|
else if (retval == -ENOMEM)
|
|
retval = -EAGAIN;
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* mlock_vma_pages_range() - mlock pages in specified vma range.
|
|
* @vma - the vma containing the specfied address range
|
|
* @start - starting address in @vma to mlock
|
|
* @end - end address [+1] in @vma to mlock
|
|
*
|
|
* For mmap()/mremap()/expansion of mlocked vma.
|
|
*
|
|
* return 0 on success for "normal" vmas.
|
|
*
|
|
* return number of pages [> 0] to be removed from locked_vm on success
|
|
* of "special" vmas.
|
|
*/
|
|
long mlock_vma_pages_range(struct vm_area_struct *vma,
|
|
unsigned long start, unsigned long end)
|
|
{
|
|
int nr_pages = (end - start) / PAGE_SIZE;
|
|
BUG_ON(!(vma->vm_flags & VM_LOCKED));
|
|
|
|
/*
|
|
* filter unlockable vmas
|
|
*/
|
|
if (vma->vm_flags & (VM_IO | VM_PFNMAP))
|
|
goto no_mlock;
|
|
|
|
if (!((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) ||
|
|
is_vm_hugetlb_page(vma) ||
|
|
vma == get_gate_vma(current->mm))) {
|
|
|
|
__mlock_vma_pages_range(vma, start, end, NULL);
|
|
|
|
/* Hide errors from mmap() and other callers */
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* User mapped kernel pages or huge pages:
|
|
* make these pages present to populate the ptes, but
|
|
* fall thru' to reset VM_LOCKED--no need to unlock, and
|
|
* return nr_pages so these don't get counted against task's
|
|
* locked limit. huge pages are already counted against
|
|
* locked vm limit.
|
|
*/
|
|
make_pages_present(start, end);
|
|
|
|
no_mlock:
|
|
vma->vm_flags &= ~VM_LOCKED; /* and don't come back! */
|
|
return nr_pages; /* error or pages NOT mlocked */
|
|
}
|
|
|
|
/*
|
|
* munlock_vma_pages_range() - munlock all pages in the vma range.'
|
|
* @vma - vma containing range to be munlock()ed.
|
|
* @start - start address in @vma of the range
|
|
* @end - end of range in @vma.
|
|
*
|
|
* For mremap(), munmap() and exit().
|
|
*
|
|
* Called with @vma VM_LOCKED.
|
|
*
|
|
* Returns with VM_LOCKED cleared. Callers must be prepared to
|
|
* deal with this.
|
|
*
|
|
* We don't save and restore VM_LOCKED here because pages are
|
|
* still on lru. In unmap path, pages might be scanned by reclaim
|
|
* and re-mlocked by try_to_{munlock|unmap} before we unmap and
|
|
* free them. This will result in freeing mlocked pages.
|
|
*/
|
|
void munlock_vma_pages_range(struct vm_area_struct *vma,
|
|
unsigned long start, unsigned long end)
|
|
{
|
|
unsigned long addr;
|
|
|
|
lru_add_drain();
|
|
vma->vm_flags &= ~VM_LOCKED;
|
|
|
|
for (addr = start; addr < end; addr += PAGE_SIZE) {
|
|
struct page *page;
|
|
/*
|
|
* Although FOLL_DUMP is intended for get_dump_page(),
|
|
* it just so happens that its special treatment of the
|
|
* ZERO_PAGE (returning an error instead of doing get_page)
|
|
* suits munlock very well (and if somehow an abnormal page
|
|
* has sneaked into the range, we won't oops here: great).
|
|
*/
|
|
page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
|
|
if (page && !IS_ERR(page)) {
|
|
lock_page(page);
|
|
/*
|
|
* Like in __mlock_vma_pages_range(),
|
|
* because we lock page here and migration is
|
|
* blocked by the elevated reference, we need
|
|
* only check for file-cache page truncation.
|
|
*/
|
|
if (page->mapping)
|
|
munlock_vma_page(page);
|
|
unlock_page(page);
|
|
put_page(page);
|
|
}
|
|
cond_resched();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* mlock_fixup - handle mlock[all]/munlock[all] requests.
|
|
*
|
|
* Filters out "special" vmas -- VM_LOCKED never gets set for these, and
|
|
* munlock is a no-op. However, for some special vmas, we go ahead and
|
|
* populate the ptes via make_pages_present().
|
|
*
|
|
* For vmas that pass the filters, merge/split as appropriate.
|
|
*/
|
|
static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
|
|
unsigned long start, unsigned long end, vm_flags_t newflags)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
pgoff_t pgoff;
|
|
int nr_pages;
|
|
int ret = 0;
|
|
int lock = !!(newflags & VM_LOCKED);
|
|
|
|
if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) ||
|
|
is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm))
|
|
goto out; /* don't set VM_LOCKED, don't count */
|
|
|
|
pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
|
|
*prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
|
|
vma->vm_file, pgoff, vma_policy(vma));
|
|
if (*prev) {
|
|
vma = *prev;
|
|
goto success;
|
|
}
|
|
|
|
if (start != vma->vm_start) {
|
|
ret = split_vma(mm, vma, start, 1);
|
|
if (ret)
|
|
goto out;
|
|
}
|
|
|
|
if (end != vma->vm_end) {
|
|
ret = split_vma(mm, vma, end, 0);
|
|
if (ret)
|
|
goto out;
|
|
}
|
|
|
|
success:
|
|
/*
|
|
* Keep track of amount of locked VM.
|
|
*/
|
|
nr_pages = (end - start) >> PAGE_SHIFT;
|
|
if (!lock)
|
|
nr_pages = -nr_pages;
|
|
mm->locked_vm += nr_pages;
|
|
|
|
/*
|
|
* vm_flags is protected by the mmap_sem held in write mode.
|
|
* It's okay if try_to_unmap_one unmaps a page just after we
|
|
* set VM_LOCKED, __mlock_vma_pages_range will bring it back.
|
|
*/
|
|
|
|
if (lock)
|
|
vma->vm_flags = newflags;
|
|
else
|
|
munlock_vma_pages_range(vma, start, end);
|
|
|
|
out:
|
|
*prev = vma;
|
|
return ret;
|
|
}
|
|
|
|
static int do_mlock(unsigned long start, size_t len, int on)
|
|
{
|
|
unsigned long nstart, end, tmp;
|
|
struct vm_area_struct * vma, * prev;
|
|
int error;
|
|
|
|
VM_BUG_ON(start & ~PAGE_MASK);
|
|
VM_BUG_ON(len != PAGE_ALIGN(len));
|
|
end = start + len;
|
|
if (end < start)
|
|
return -EINVAL;
|
|
if (end == start)
|
|
return 0;
|
|
vma = find_vma_prev(current->mm, start, &prev);
|
|
if (!vma || vma->vm_start > start)
|
|
return -ENOMEM;
|
|
|
|
if (start > vma->vm_start)
|
|
prev = vma;
|
|
|
|
for (nstart = start ; ; ) {
|
|
vm_flags_t newflags;
|
|
|
|
/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
|
|
|
|
newflags = vma->vm_flags | VM_LOCKED;
|
|
if (!on)
|
|
newflags &= ~VM_LOCKED;
|
|
|
|
tmp = vma->vm_end;
|
|
if (tmp > end)
|
|
tmp = end;
|
|
error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
|
|
if (error)
|
|
break;
|
|
nstart = tmp;
|
|
if (nstart < prev->vm_end)
|
|
nstart = prev->vm_end;
|
|
if (nstart >= end)
|
|
break;
|
|
|
|
vma = prev->vm_next;
|
|
if (!vma || vma->vm_start != nstart) {
|
|
error = -ENOMEM;
|
|
break;
|
|
}
|
|
}
|
|
return error;
|
|
}
|
|
|
|
static int do_mlock_pages(unsigned long start, size_t len, int ignore_errors)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
unsigned long end, nstart, nend;
|
|
struct vm_area_struct *vma = NULL;
|
|
int locked = 0;
|
|
int ret = 0;
|
|
|
|
VM_BUG_ON(start & ~PAGE_MASK);
|
|
VM_BUG_ON(len != PAGE_ALIGN(len));
|
|
end = start + len;
|
|
|
|
for (nstart = start; nstart < end; nstart = nend) {
|
|
/*
|
|
* We want to fault in pages for [nstart; end) address range.
|
|
* Find first corresponding VMA.
|
|
*/
|
|
if (!locked) {
|
|
locked = 1;
|
|
down_read(&mm->mmap_sem);
|
|
vma = find_vma(mm, nstart);
|
|
} else if (nstart >= vma->vm_end)
|
|
vma = vma->vm_next;
|
|
if (!vma || vma->vm_start >= end)
|
|
break;
|
|
/*
|
|
* Set [nstart; nend) to intersection of desired address
|
|
* range with the first VMA. Also, skip undesirable VMA types.
|
|
*/
|
|
nend = min(end, vma->vm_end);
|
|
if (vma->vm_flags & (VM_IO | VM_PFNMAP))
|
|
continue;
|
|
if (nstart < vma->vm_start)
|
|
nstart = vma->vm_start;
|
|
/*
|
|
* Now fault in a range of pages. __mlock_vma_pages_range()
|
|
* double checks the vma flags, so that it won't mlock pages
|
|
* if the vma was already munlocked.
|
|
*/
|
|
ret = __mlock_vma_pages_range(vma, nstart, nend, &locked);
|
|
if (ret < 0) {
|
|
if (ignore_errors) {
|
|
ret = 0;
|
|
continue; /* continue at next VMA */
|
|
}
|
|
ret = __mlock_posix_error_return(ret);
|
|
break;
|
|
}
|
|
nend = nstart + ret * PAGE_SIZE;
|
|
ret = 0;
|
|
}
|
|
if (locked)
|
|
up_read(&mm->mmap_sem);
|
|
return ret; /* 0 or negative error code */
|
|
}
|
|
|
|
SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
|
|
{
|
|
unsigned long locked;
|
|
unsigned long lock_limit;
|
|
int error = -ENOMEM;
|
|
|
|
if (!can_do_mlock())
|
|
return -EPERM;
|
|
|
|
lru_add_drain_all(); /* flush pagevec */
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
|
|
start &= PAGE_MASK;
|
|
|
|
locked = len >> PAGE_SHIFT;
|
|
locked += current->mm->locked_vm;
|
|
|
|
lock_limit = rlimit(RLIMIT_MEMLOCK);
|
|
lock_limit >>= PAGE_SHIFT;
|
|
|
|
/* check against resource limits */
|
|
if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
|
|
error = do_mlock(start, len, 1);
|
|
up_write(¤t->mm->mmap_sem);
|
|
if (!error)
|
|
error = do_mlock_pages(start, len, 0);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
|
|
{
|
|
int ret;
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
|
|
start &= PAGE_MASK;
|
|
ret = do_mlock(start, len, 0);
|
|
up_write(¤t->mm->mmap_sem);
|
|
return ret;
|
|
}
|
|
|
|
static int do_mlockall(int flags)
|
|
{
|
|
struct vm_area_struct * vma, * prev = NULL;
|
|
unsigned int def_flags = 0;
|
|
|
|
if (flags & MCL_FUTURE)
|
|
def_flags = VM_LOCKED;
|
|
current->mm->def_flags = def_flags;
|
|
if (flags == MCL_FUTURE)
|
|
goto out;
|
|
|
|
for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
|
|
vm_flags_t newflags;
|
|
|
|
newflags = vma->vm_flags | VM_LOCKED;
|
|
if (!(flags & MCL_CURRENT))
|
|
newflags &= ~VM_LOCKED;
|
|
|
|
/* Ignore errors */
|
|
mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
|
|
}
|
|
out:
|
|
return 0;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(mlockall, int, flags)
|
|
{
|
|
unsigned long lock_limit;
|
|
int ret = -EINVAL;
|
|
|
|
if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
|
|
goto out;
|
|
|
|
ret = -EPERM;
|
|
if (!can_do_mlock())
|
|
goto out;
|
|
|
|
lru_add_drain_all(); /* flush pagevec */
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
|
|
lock_limit = rlimit(RLIMIT_MEMLOCK);
|
|
lock_limit >>= PAGE_SHIFT;
|
|
|
|
ret = -ENOMEM;
|
|
if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
|
|
capable(CAP_IPC_LOCK))
|
|
ret = do_mlockall(flags);
|
|
up_write(¤t->mm->mmap_sem);
|
|
if (!ret && (flags & MCL_CURRENT)) {
|
|
/* Ignore errors */
|
|
do_mlock_pages(0, TASK_SIZE, 1);
|
|
}
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
SYSCALL_DEFINE0(munlockall)
|
|
{
|
|
int ret;
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
ret = do_mlockall(0);
|
|
up_write(¤t->mm->mmap_sem);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
|
|
* shm segments) get accounted against the user_struct instead.
|
|
*/
|
|
static DEFINE_SPINLOCK(shmlock_user_lock);
|
|
|
|
int user_shm_lock(size_t size, struct user_struct *user)
|
|
{
|
|
unsigned long lock_limit, locked;
|
|
int allowed = 0;
|
|
|
|
locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
lock_limit = rlimit(RLIMIT_MEMLOCK);
|
|
if (lock_limit == RLIM_INFINITY)
|
|
allowed = 1;
|
|
lock_limit >>= PAGE_SHIFT;
|
|
spin_lock(&shmlock_user_lock);
|
|
if (!allowed &&
|
|
locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
|
|
goto out;
|
|
get_uid(user);
|
|
user->locked_shm += locked;
|
|
allowed = 1;
|
|
out:
|
|
spin_unlock(&shmlock_user_lock);
|
|
return allowed;
|
|
}
|
|
|
|
void user_shm_unlock(size_t size, struct user_struct *user)
|
|
{
|
|
spin_lock(&shmlock_user_lock);
|
|
user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
spin_unlock(&shmlock_user_lock);
|
|
free_uid(user);
|
|
}
|