svn commit: r319317 - head/sys/compat/linuxkpi/common/src

[Hans Petter Selasky]

Author: hselasky
Date: Wed May 31 12:08:25 2017
New Revision: 319317
URL: https://svnweb.freebsd.org/changeset/base/319317

Log:
  Fix a reference count leak in the LinuxKPI due to calling VM open when
  it shouldn't be called.
  
  Background:
  The Linux VM open operation is called when a new VMA is
  created on top of the current VMA. This is done through either mremap
  flow or split_vma, usually due to mlock, madvise, munmap and so
  on. This is currently not supported by the LinuxKPI.
  
  MFC after:		1 week
  Sponsored by:		Mellanox Technologies

Modified:
  head/sys/compat/linuxkpi/common/src/linux_compat.c

Modified: head/sys/compat/linuxkpi/common/src/linux_compat.c
==============================================================================
--- head/sys/compat/linuxkpi/common/src/linux_compat.c	Wed May 31 12:02:59 2017	(r319316)
+++ head/sys/compat/linuxkpi/common/src/linux_compat.c	Wed May 31 12:08:25 2017	(r319317)
@@ -547,20 +547,9 @@ static int
 linux_cdev_pager_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
 		      vm_ooffset_t foff, struct ucred *cred, u_short *color)
 {
-	const struct vm_operations_struct *vm_ops;
-	struct vm_area_struct *vmap;
 
-	vmap = linux_cdev_handle_find(handle);
-	MPASS(vmap != NULL);
-
+	MPASS(linux_cdev_handle_find(handle) != NULL);
 	*color = 0;
-
-	down_write(&vmap->vm_mm->mmap_sem);
-	vm_ops = vmap->vm_ops;
-	if (likely(vm_ops != NULL))
-		vm_ops->open(vmap);
-	up_write(&vmap->vm_mm->mmap_sem);
-
 	return (0);
 }