xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

userfaultfd: non-cooperative: add event for memory unmaps

Browse Source 
When a non-cooperative userfaultfd monitor copies pages in the
background, it may encounter regions that were already unmapped.
Addition of UFFD_EVENT_UNMAP allows the uffd monitor to track precisely
changes in the virtual memory layout.

Since there might be different uffd contexts for the affected VMAs, we
first should create a temporary representation for the unmap event for
each uffd context and then notify them one by one to the appropriate
userfault file descriptors.

The event notification occurs after the mmap_sem has been released.

[arnd@arndb.de: fix nommu build]
  Link: http://lkml.kernel.org/r/20170203165141.3665284-1-arnd@arndb.de
[mhocko@suse.com: fix nommu build]
  Link: http://lkml.kernel.org/r/20170202091503.GA22823@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/1485542673-24387-3-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Rapoport
2017-02-24 14:58:22 -08:00
committed by Linus Torvalds
parent 846b1a0f1d
commit 897ab3e0c4
15 changed files with 160 additions and 45 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
mm/nommu.c
View File

@@ -1205,7 +1205,8 @@ unsigned long do_mmap(struct file *file,
unsigned long flags,
vm_flags_t vm_flags,
unsigned long pgoff,
unsigned long *populate)
unsigned long *populate,
struct list_head *uf)
{
struct vm_area_struct *vma;
struct vm_region *region;
@@ -1577,7 +1578,7 @@ static int shrink_vma(struct mm_struct *mm,
* - under NOMMU conditions the chunk to be unmapped must be backed by a single
* VMA, though it need not cover the whole VMA
*/
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, struct list_head *uf)
{
struct vm_area_struct *vma;
unsigned long end;
@@ -1643,7 +1644,7 @@ int vm_munmap(unsigned long addr, size_t len)
int ret;
down_write(&mm->mmap_sem);
ret = do_munmap(mm, addr, len);
ret = do_munmap(mm, addr, len, NULL);
up_write(&mm->mmap_sem);
return ret;
}