The following flag comparison in mmap_region makes no sense:
if (!(vm_flags & MAP_FIXED))
return -ENOMEM;
The condition is false even if MAP_FIXED is not set what causes the
unnecessary find_vma call. MAP_FIXED has the same value as VM_MAYREAD.
The vm_flags must not be compared with MAP_FIXED. The vm_flags may only
be compared with VM_* flags. The mmap executes slightly longer when
MAP_FIXED is not set and RLIMIT_AS is exceeded.
Fix the issue by introducing a new parameter to mmap_region which forwards
the mmap flags and now the MAP_FIXED can be checked properly.
Tile and its arch_setup_additional_pages as the user of
mmap_region has to be specific about its mmap flags now.
Signed-off-by: Piotr Kwapulinski <kwapulinski.piotr@xxxxxxxxx>
---
arch/tile/mm/elf.c | 1 +
include/linux/mm.h | 3 ++-
mm/mmap.c | 7 ++++---
3 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/arch/tile/mm/elf.c b/arch/tile/mm/elf.c
index 6225cc9..dae4b33 100644
--- a/arch/tile/mm/elf.c
+++ b/arch/tile/mm/elf.c
@@ -142,6 +142,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
if (!retval) {
unsigned long addr = MEM_USER_INTRPT;
addr = mmap_region(NULL, addr, INTRPT_SIZE,
+ MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 0);
if (addr > (unsigned long) -PAGE_SIZE)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 00bad77..f1a203f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1911,7 +1911,8 @@ extern int install_special_mapping(struct mm_struct *mm,
extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
extern unsigned long mmap_region(struct file *file, unsigned long addr,
- unsigned long len, vm_flags_t vm_flags, unsigned long pgoff);
+ unsigned long len, unsigned long mmap_flags,
+ vm_flags_t vm_flags, unsigned long pgoff);
extern unsigned long do_mmap(struct file *file, unsigned long addr,
unsigned long len, unsigned long prot, unsigned long flags,
vm_flags_t vm_flags, unsigned long pgoff, unsigned long *populate);
diff --git a/mm/mmap.c b/mm/mmap.c
index 2ce04a6..8f3427f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1399,7 +1399,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
vm_flags |= VM_NORESERVE;
}
- addr = mmap_region(file, addr, len, vm_flags, pgoff);
+ addr = mmap_region(file, addr, len, flags, vm_flags, pgoff);
if (!IS_ERR_VALUE(addr) &&
((vm_flags & VM_LOCKED) ||
(flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
@@ -1535,7 +1535,8 @@ static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
}
unsigned long mmap_region(struct file *file, unsigned long addr,
- unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
+ unsigned long len, unsigned long mmap_flags,
+ vm_flags_t vm_flags, unsigned long pgoff)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma, *prev;
@@ -1551,7 +1552,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
* MAP_FIXED may remove pages of mappings that intersects with
* requested mapping. Account for the pages it would unmap.
*/
- if (!(vm_flags & MAP_FIXED))
+ if (!(mmap_flags & MAP_FIXED))
return -ENOMEM;
nr_pages = count_vma_pages_range(mm, addr, addr + len);
--
2.6.2
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