VM: add "vm_mmap()" helper function

This continues the theme started with vm_brk() and vm_munmap():
vm_mmap() does the same thing as do_mmap(), but additionally does the
required VM locking.

This uninlines (and rewrites it to be clearer) do_mmap(), which sadly
duplicates it in mm/mmap.c and mm/nommu.c.  But that way we don't have
to export our internal do_mmap_pgoff() function.

Some day we hopefully don't have to export do_mmap() either, if all
modular users can become the simpler vm_mmap() instead.  We're actually
very close to that already, with the notable exception of the (broken)
use in i810, and a couple of stragglers in binfmt_elf.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 3 deletions

diff --git a/arch/tile/kernel/single_step.c b/arch/tile/kernel/single_step.c
index 9efbc1391b3c..89529c9f0605 100644
--- a/arch/tile/kernel/single_step.c
+++ b/arch/tile/kernel/single_step.c
@@ -346,12 +346,10 @@ void single_step_once(struct pt_regs *regs)
                 }
 
                 /* allocate a cache line of writable, executable memory */
-                down_write(&current->mm->mmap_sem);
-                buffer = (void __user *) do_mmap(NULL, 0, 64,
+                buffer = (void __user *) vm_mmap(NULL, 0, 64,
                                           PROT_EXEC | PROT_READ | PROT_WRITE,
                                           MAP_PRIVATE | MAP_ANONYMOUS,
                                           0);
-                up_write(&current->mm->mmap_sem);
 
                 if (IS_ERR((void __force *)buffer)) {
                         kfree(state);