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-rw-r--r--mm/mlock.c47
1 files changed, 2 insertions, 45 deletions
diff --git a/mm/mlock.c b/mm/mlock.c
index 2904a34..028ec48 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -294,14 +294,10 @@ static inline int __mlock_posix_error_return(long retval)
*
* return number of pages [> 0] to be removed from locked_vm on success
* of "special" vmas.
- *
- * return negative error if vma spanning @start-@range disappears while
- * mmap semaphore is dropped. Unlikely?
*/
long mlock_vma_pages_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
- struct mm_struct *mm = vma->vm_mm;
int nr_pages = (end - start) / PAGE_SIZE;
BUG_ON(!(vma->vm_flags & VM_LOCKED));
@@ -314,20 +310,8 @@ long mlock_vma_pages_range(struct vm_area_struct *vma,
if (!((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) ||
is_vm_hugetlb_page(vma) ||
vma == get_gate_vma(current))) {
- long error;
- downgrade_write(&mm->mmap_sem);
-
- error = __mlock_vma_pages_range(vma, start, end, 1);
- up_read(&mm->mmap_sem);
- /* vma can change or disappear */
- down_write(&mm->mmap_sem);
- vma = find_vma(mm, start);
- /* non-NULL vma must contain @start, but need to check @end */
- if (!vma || end > vma->vm_end)
- return -ENOMEM;
-
- return 0; /* hide other errors from mmap(), et al */
+ return __mlock_vma_pages_range(vma, start, end, 1);
}
/*
@@ -438,41 +422,14 @@ success:
vma->vm_flags = newflags;
if (lock) {
- /*
- * mmap_sem is currently held for write. Downgrade the write
- * lock to a read lock so that other faults, mmap scans, ...
- * while we fault in all pages.
- */
- downgrade_write(&mm->mmap_sem);
-
ret = __mlock_vma_pages_range(vma, start, end, 1);
- /*
- * Need to reacquire mmap sem in write mode, as our callers
- * expect this. We have no support for atomically upgrading
- * a sem to write, so we need to check for ranges while sem
- * is unlocked.
- */
- up_read(&mm->mmap_sem);
- /* vma can change or disappear */
- down_write(&mm->mmap_sem);
- *prev = find_vma(mm, start);
- /* non-NULL *prev must contain @start, but need to check @end */
- if (!(*prev) || end > (*prev)->vm_end)
- ret = -ENOMEM;
- else if (ret > 0) {
+ if (ret > 0) {
mm->locked_vm -= ret;
ret = 0;
} else
ret = __mlock_posix_error_return(ret); /* translate if needed */
} else {
- /*
- * TODO: for unlocking, pages will already be resident, so
- * we don't need to wait for allocations/reclaim/pagein, ...
- * However, unlocking a very large region can still take a
- * while. Should we downgrade the semaphore for both lock
- * AND unlock ?
- */
__mlock_vma_pages_range(vma, start, end, 0);
}
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