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-rw-r--r--mm/mmap.c59
1 files changed, 48 insertions, 11 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index f7cd9cb966c0..330f12c17fa1 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2687,8 +2687,8 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
* work. This now handles partial unmappings.
* Jeremy Fitzhardinge <jeremy@goop.org>
*/
-int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
- struct list_head *uf)
+static int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
+ struct list_head *uf, bool downgrade)
{
unsigned long end;
struct vm_area_struct *vma, *prev, *last;
@@ -2770,25 +2770,47 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
mm->locked_vm -= vma_pages(tmp);
munlock_vma_pages_all(tmp);
}
+
+ /*
+ * Unmapping vmas, which have VM_HUGETLB or VM_PFNMAP,
+ * need get done with write mmap_sem held since they may
+ * update vm_flags.
+ */
+ if (downgrade &&
+ (tmp->vm_flags & (VM_HUGETLB | VM_PFNMAP)))
+ downgrade = false;
+
tmp = tmp->vm_next;
}
}
- /*
- * Remove the vma's, and unmap the actual pages
- */
+ /* Detach vmas from rbtree */
detach_vmas_to_be_unmapped(mm, vma, prev, end);
- unmap_region(mm, vma, prev, start, end);
+ /*
+ * mpx unmap needs to be called with mmap_sem held for write.
+ * It is safe to call it before unmap_region().
+ */
arch_unmap(mm, vma, start, end);
+ if (downgrade)
+ downgrade_write(&mm->mmap_sem);
+
+ unmap_region(mm, vma, prev, start, end);
+
/* Fix up all other VM information */
remove_vma_list(mm, vma);
- return 0;
+ return downgrade ? 1 : 0;
}
-int vm_munmap(unsigned long start, size_t len)
+int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
+ struct list_head *uf)
+{
+ return __do_munmap(mm, start, len, uf, false);
+}
+
+static int __vm_munmap(unsigned long start, size_t len, bool downgrade)
{
int ret;
struct mm_struct *mm = current->mm;
@@ -2797,17 +2819,32 @@ int vm_munmap(unsigned long start, size_t len)
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
- ret = do_munmap(mm, start, len, &uf);
- up_write(&mm->mmap_sem);
+ ret = __do_munmap(mm, start, len, &uf, downgrade);
+ /*
+ * Returning 1 indicates mmap_sem is downgraded.
+ * But 1 is not legal return value of vm_munmap() and munmap(), reset
+ * it to 0 before return.
+ */
+ if (ret == 1) {
+ up_read(&mm->mmap_sem);
+ ret = 0;
+ } else
+ up_write(&mm->mmap_sem);
+
userfaultfd_unmap_complete(mm, &uf);
return ret;
}
+
+int vm_munmap(unsigned long start, size_t len)
+{
+ return __vm_munmap(start, len, false);
+}
EXPORT_SYMBOL(vm_munmap);
SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
{
profile_munmap(addr);
- return vm_munmap(addr, len);
+ return __vm_munmap(addr, len, true);
}