diff --git a/include/uapi/linux/mman.h b/include/uapi/linux/mman.h
index fc1a64c3447bf6e329bba5e155053332794a0187..923cc162609c016dd6360d834b34abfe6e1ba459 100644
--- a/include/uapi/linux/mman.h
+++ b/include/uapi/linux/mman.h
@@ -5,8 +5,9 @@
#include <asm/mman.h>
#include <asm-generic/hugetlb_encode.h>
-#define MREMAP_MAYMOVE 1
-#define MREMAP_FIXED 2
+#define MREMAP_MAYMOVE 1
+#define MREMAP_FIXED 2
+#define MREMAP_DONTUNMAP 4
#define OVERCOMMIT_GUESS 0
#define OVERCOMMIT_ALWAYS 1
diff --git a/mm/mremap.c b/mm/mremap.c
index ab1bdaff0515d4e35fd64a5d6ea57c3ec8c10c98..a7e282ead43800031af363affaf39ac65ff0b307 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -318,8 +318,8 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
static unsigned long move_vma(struct vm_area_struct *vma,
unsigned long old_addr, unsigned long old_len,
unsigned long new_len, unsigned long new_addr,
- bool *locked, struct vm_userfaultfd_ctx *uf,
- struct list_head *uf_unmap)
+ bool *locked, unsigned long flags,
+ struct vm_userfaultfd_ctx *uf, struct list_head *uf_unmap)
{
struct mm_struct *mm = vma->vm_mm;
struct vm_area_struct *new_vma;
@@ -408,11 +408,32 @@ static unsigned long move_vma(struct vm_area_struct *vma,
if (unlikely(vma->vm_flags & VM_PFNMAP))
untrack_pfn_moved(vma);
+ if (unlikely(!err && (flags & MREMAP_DONTUNMAP))) {
+ if (vm_flags & VM_ACCOUNT) {
+ /* Always put back VM_ACCOUNT since we won't unmap */
+ vma->vm_flags |= VM_ACCOUNT;
+
+ vm_acct_memory(vma_pages(new_vma));
+ }
+
+ /* We always clear VM_LOCKED[ONFAULT] on the old vma */
+ vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
+
+ /* Because we won't unmap we don't need to touch locked_vm */
+ goto out;
+ }
+
if (do_munmap(mm, old_addr, old_len, uf_unmap) < 0) {
/* OOM: unable to split vma, just get accounts right */
vm_unacct_memory(excess >> PAGE_SHIFT);
excess = 0;
}
+
+ if (vm_flags & VM_LOCKED) {
+ mm->locked_vm += new_len >> PAGE_SHIFT;
+ *locked = true;
+ }
+out:
mm->hiwater_vm = hiwater_vm;
/* Restore VM_ACCOUNT if one or two pieces of vma left */
@@ -422,16 +443,12 @@ static unsigned long move_vma(struct vm_area_struct *vma,
vma->vm_next->vm_flags |= VM_ACCOUNT;
}
- if (vm_flags & VM_LOCKED) {
- mm->locked_vm += new_len >> PAGE_SHIFT;
- *locked = true;
- }
-
return new_addr;
}
static struct vm_area_struct *vma_to_resize(unsigned long addr,
- unsigned long old_len, unsigned long new_len, unsigned long *p)
+ unsigned long old_len, unsigned long new_len, unsigned long flags,
+ unsigned long *p)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma = find_vma(mm, addr);
@@ -453,6 +470,10 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr,
return ERR_PTR(-EINVAL);
}
+ if (flags & MREMAP_DONTUNMAP && (!vma_is_anonymous(vma) ||
+ vma->vm_flags & VM_SHARED))
+ return ERR_PTR(-EINVAL);
+
if (is_vm_hugetlb_page(vma))
return ERR_PTR(-EINVAL);
@@ -497,7 +518,7 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr,
static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
unsigned long new_addr, unsigned long new_len, bool *locked,
- struct vm_userfaultfd_ctx *uf,
+ unsigned long flags, struct vm_userfaultfd_ctx *uf,
struct list_head *uf_unmap_early,
struct list_head *uf_unmap)
{
@@ -505,7 +526,7 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
struct vm_area_struct *vma;
unsigned long ret = -EINVAL;
unsigned long charged = 0;
- unsigned long map_flags;
+ unsigned long map_flags = 0;
if (offset_in_page(new_addr))
goto out;
@@ -534,9 +555,11 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
if ((mm->map_count + 2) >= sysctl_max_map_count - 3)
return -ENOMEM;
- ret = do_munmap(mm, new_addr, new_len, uf_unmap_early);
- if (ret)
- goto out;
+ if (flags & MREMAP_FIXED) {
+ ret = do_munmap(mm, new_addr, new_len, uf_unmap_early);
+ if (ret)
+ goto out;
+ }
if (old_len >= new_len) {
ret = do_munmap(mm, addr+new_len, old_len - new_len, uf_unmap);
@@ -545,13 +568,22 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
old_len = new_len;
}
- vma = vma_to_resize(addr, old_len, new_len, &charged);
+ vma = vma_to_resize(addr, old_len, new_len, flags, &charged);
if (IS_ERR(vma)) {
ret = PTR_ERR(vma);
goto out;
}
- map_flags = MAP_FIXED;
+ /* MREMAP_DONTUNMAP expands by old_len since old_len == new_len */
+ if (flags & MREMAP_DONTUNMAP &&
+ !may_expand_vm(mm, vma->vm_flags, old_len >> PAGE_SHIFT)) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ if (flags & MREMAP_FIXED)
+ map_flags |= MAP_FIXED;
+
if (vma->vm_flags & VM_MAYSHARE)
map_flags |= MAP_SHARED;
@@ -561,10 +593,16 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
if (IS_ERR_VALUE(ret))
goto out1;
- ret = move_vma(vma, addr, old_len, new_len, new_addr, locked, uf,
+ /* We got a new mapping */
+ if (!(flags & MREMAP_FIXED))
+ new_addr = ret;
+
+ ret = move_vma(vma, addr, old_len, new_len, new_addr, locked, flags, uf,
uf_unmap);
+
if (!(offset_in_page(ret)))
goto out;
+
out1:
vm_unacct_memory(charged);
@@ -618,12 +656,21 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
*/
addr = untagged_addr(addr);
- if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
+ if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE | MREMAP_DONTUNMAP))
return ret;
if (flags & MREMAP_FIXED && !(flags & MREMAP_MAYMOVE))
return ret;
+ /*
+ * MREMAP_DONTUNMAP is always a move and it does not allow resizing
+ * in the process.
+ */
+ if (flags & MREMAP_DONTUNMAP &&
+ (!(flags & MREMAP_MAYMOVE) || old_len != new_len))
+ return ret;
+
+
if (offset_in_page(addr))
return ret;
@@ -641,9 +688,10 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
if (down_write_killable(¤t->mm->mmap_sem))
return -EINTR;
- if (flags & MREMAP_FIXED) {
+ if (flags & (MREMAP_FIXED | MREMAP_DONTUNMAP)) {
ret = mremap_to(addr, old_len, new_addr, new_len,
- &locked, &uf, &uf_unmap_early, &uf_unmap);
+ &locked, flags, &uf, &uf_unmap_early,
+ &uf_unmap);
goto out;
}
@@ -671,7 +719,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
/*
* Ok, we need to grow..
*/
- vma = vma_to_resize(addr, old_len, new_len, &charged);
+ vma = vma_to_resize(addr, old_len, new_len, flags, &charged);
if (IS_ERR(vma)) {
ret = PTR_ERR(vma);
goto out;
@@ -721,7 +769,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
}
ret = move_vma(vma, addr, old_len, new_len, new_addr,
- &locked, &uf, &uf_unmap);
+ &locked, flags, &uf, &uf_unmap);
}
out:
if (offset_in_page(ret)) {