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Diffstat (limited to 'mm/mmap.c')
-rw-r--r--mm/mmap.c85
1 files changed, 49 insertions, 36 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index d3fa10a726c..00ced3ee49a 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -658,6 +658,9 @@ again: remove_next = 1 + (end > next->vm_end);
validate_mm(mm);
}
+/* Flags that can be inherited from an existing mapping when merging */
+#define VM_MERGEABLE_FLAGS (VM_CAN_NONLINEAR)
+
/*
* If the vma has a ->close operation then the driver probably needs to release
* per-vma resources, so we don't attempt to merge those.
@@ -665,7 +668,7 @@ again: remove_next = 1 + (end > next->vm_end);
static inline int is_mergeable_vma(struct vm_area_struct *vma,
struct file *file, unsigned long vm_flags)
{
- if (vma->vm_flags != vm_flags)
+ if ((vma->vm_flags ^ vm_flags) & ~VM_MERGEABLE_FLAGS)
return 0;
if (vma->vm_file != file)
return 0;
@@ -915,7 +918,6 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
struct inode *inode;
unsigned int vm_flags;
int error;
- int accountable = 1;
unsigned long reqprot = prot;
/*
@@ -1016,8 +1018,6 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
return -EPERM;
vm_flags &= ~VM_MAYEXEC;
}
- if (is_file_hugepages(file))
- accountable = 0;
if (!file->f_op || !file->f_op->mmap)
return -ENODEV;
@@ -1050,8 +1050,7 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
if (error)
return error;
- return mmap_region(file, addr, len, flags, vm_flags, pgoff,
- accountable);
+ return mmap_region(file, addr, len, flags, vm_flags, pgoff);
}
EXPORT_SYMBOL(do_mmap_pgoff);
@@ -1087,10 +1086,25 @@ int vma_wants_writenotify(struct vm_area_struct *vma)
mapping_cap_account_dirty(vma->vm_file->f_mapping);
}
+/*
+ * We account for memory if it's a private writeable mapping,
+ * not hugepages and VM_NORESERVE wasn't set.
+ */
+static inline int accountable_mapping(struct file *file, unsigned int vm_flags)
+{
+ /*
+ * hugetlb has its own accounting separate from the core VM
+ * VM_HUGETLB may not be set yet so we cannot check for that flag.
+ */
+ if (file && is_file_hugepages(file))
+ return 0;
+
+ return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
+}
+
unsigned long mmap_region(struct file *file, unsigned long addr,
unsigned long len, unsigned long flags,
- unsigned int vm_flags, unsigned long pgoff,
- int accountable)
+ unsigned int vm_flags, unsigned long pgoff)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma, *prev;
@@ -1114,23 +1128,28 @@ munmap_back:
if (!may_expand_vm(mm, len >> PAGE_SHIFT))
return -ENOMEM;
- if (flags & MAP_NORESERVE)
- vm_flags |= VM_NORESERVE;
+ /*
+ * Set 'VM_NORESERVE' if we should not account for the
+ * memory use of this mapping.
+ */
+ if ((flags & MAP_NORESERVE)) {
+ /* We honor MAP_NORESERVE if allowed to overcommit */
+ if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
+ vm_flags |= VM_NORESERVE;
- if (accountable && (!(flags & MAP_NORESERVE) ||
- sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
- if (vm_flags & VM_SHARED) {
- /* Check memory availability in shmem_file_setup? */
- vm_flags |= VM_ACCOUNT;
- } else if (vm_flags & VM_WRITE) {
- /*
- * Private writable mapping: check memory availability
- */
- charged = len >> PAGE_SHIFT;
- if (security_vm_enough_memory(charged))
- return -ENOMEM;
- vm_flags |= VM_ACCOUNT;
- }
+ /* hugetlb applies strict overcommit unless MAP_NORESERVE */
+ if (file && is_file_hugepages(file))
+ vm_flags |= VM_NORESERVE;
+ }
+
+ /*
+ * Private writable mapping: check memory availability
+ */
+ if (accountable_mapping(file, vm_flags)) {
+ charged = len >> PAGE_SHIFT;
+ if (security_vm_enough_memory(charged))
+ return -ENOMEM;
+ vm_flags |= VM_ACCOUNT;
}
/*
@@ -1181,14 +1200,6 @@ munmap_back:
goto free_vma;
}
- /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
- * shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
- * that memory reservation must be checked; but that reservation
- * belongs to shared memory object, not to vma: so now clear it.
- */
- if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
- vma->vm_flags &= ~VM_ACCOUNT;
-
/* Can addr have changed??
*
* Answer: Yes, several device drivers can do it in their
@@ -2073,12 +2084,8 @@ void exit_mmap(struct mm_struct *mm)
unsigned long end;
/* mm's last user has gone, and its about to be pulled down */
- arch_exit_mmap(mm);
mmu_notifier_release(mm);
- if (!mm->mmap) /* Can happen if dup_mmap() received an OOM */
- return;
-
if (mm->locked_vm) {
vma = mm->mmap;
while (vma) {
@@ -2087,7 +2094,13 @@ void exit_mmap(struct mm_struct *mm)
vma = vma->vm_next;
}
}
+
+ arch_exit_mmap(mm);
+
vma = mm->mmap;
+ if (!vma) /* Can happen if dup_mmap() received an OOM */
+ return;
+
lru_add_drain();
flush_cache_mm(mm);
tlb = tlb_gather_mmu(mm, 1);