diff mbox

[04/13] vrange: Clear volatility on new mmaps

Message ID 1370913139-9320-5-git-send-email-john.stultz@linaro.org
State Superseded
Headers show

Commit Message

John Stultz June 11, 2013, 1:12 a.m. UTC 
At lsf-mm, the issue was brought up that there is a precedence with
interfaces like mlock, such that new mappings in a pre-existing range
do no inherit the mlock state.

This is mostly because mlock only modifies the existing vmas, and so
any new mmaps create new vmas, which won't be mlocked.

Since volatility is not stored in the vma (for good cause, specfically
as we'd have to have manage file volatility differently from anonymous),
this patch clears volatilty on new mappings, to ensure that we don't
inherit volatility if memory in an existing volatile range is unmapped
and then re-mapped with something else.

Thus, this patch forces any volatility to be cleared on mmap.


XXX - Minchan would like to see this issue addressed differently.


Signed-off-by: John Stultz <john.stultz@linaro.org>
---
 include/linux/vrange.h | 2 ++
 mm/mmap.c              | 5 +++++
 mm/vrange.c            | 8 ++++++++
 3 files changed, 15 insertions(+)
diff mbox

Patch

diff --git a/include/linux/vrange.h b/include/linux/vrange.h
index 13f4887..a97ac25 100644
--- a/include/linux/vrange.h
+++ b/include/linux/vrange.h
@@ -32,6 +32,8 @@  static inline int vrange_type(struct vrange *vrange)
 }
 
 void vrange_init(void);
+extern int vrange_clear(struct vrange_root *vroot,
+				unsigned long start, unsigned long end);
 extern void vrange_root_cleanup(struct vrange_root *vroot);
 extern int vrange_fork(struct mm_struct *new,
 					struct mm_struct *old);
diff --git a/mm/mmap.c b/mm/mmap.c
index f681e18..80d3676 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -36,6 +36,7 @@ 
 #include <linux/sched/sysctl.h>
 #include <linux/notifier.h>
 #include <linux/memory.h>
+#include <linux/vrange.h>
 
 #include <asm/uaccess.h>
 #include <asm/cacheflush.h>
@@ -1500,6 +1501,10 @@  unsigned long mmap_region(struct file *file, unsigned long addr,
 	/* Clear old maps */
 	error = -ENOMEM;
 munmap_back:
+
+	/* zap any volatile ranges */
+	vrange_clear(&mm->vroot, addr, addr + len);
+
 	if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
 		if (do_munmap(mm, addr, len))
 			return -ENOMEM;
diff --git a/mm/vrange.c b/mm/vrange.c
index bbaa184..5ca8853 100644
--- a/mm/vrange.c
+++ b/mm/vrange.c
@@ -164,6 +164,14 @@  static int vrange_remove(struct vrange_root *vroot,
 	return 0;
 }
 
+int vrange_clear(struct vrange_root *vroot,
+					unsigned long start, unsigned long end)
+{
+	int purged;
+
+	return vrange_remove(vroot, start, end-1, &purged);
+}
+
 void vrange_root_cleanup(struct vrange_root *vroot)
 {
 	struct vrange *range;