Re: [RFC PATCH 0/5] userfaultfd: non-cooperative: better tracking for mapping changes

[Hillf Danton]

On January 24, 2017 9:52 PM Mike Rapoport wrote: 
> Hi,
> 
> These patches try to address issues I've encountered during integration of
> userfaultfd with CRIU.
> Previously added userfaultfd events for fork(), madvise() and mremap()
> unfortunately do not cover all possible changes to a process virtual memory
> layout required for uffd monitor.
> When one or more VMAs is removed from the process mm, the external uffd
> monitor has no way to detect those changes and will attempt to fill the
> removed regions with userfaultfd_copy.
> Another problematic event is the exit() of the process. Here again, the
> external uffd monitor will try to use userfaultfd_copy, although mm owning
> the memory has already gone.
> 
> The first patch in the series is a minor cleanup and it's not strictly
> related to the rest of the series.
> 
> The patches 2 and 3 below add UFFD_EVENT_UNMAP and UFFD_EVENT_EXIT to allow
> the uffd monitor track changes in the memory layout of a process.
> 
> The patches 4 and 5 amend error codes returned by userfaultfd_copy to make
> the uffd monitor able to cope with races that might occur between delivery
> of unmap and exit events and outstanding userfaultfd_copy's.
> 
> The patches are agains current -mm tree.
> 
> Mike Rapoport (5):
>   mm: call vm_munmap in munmap syscall instead of using open coded version
>   userfaultfd: non-cooperative: add event for memory unmaps
>   userfaultfd: non-cooperative: add event for exit() notification
>   userfaultfd: mcopy_atomic: return -ENOENT when no compatible VMA found
>   userfaultfd_copy: return -ENOSPC in case mm has gone
> 
>  arch/tile/mm/elf.c   |  2 +-
>  arch/x86/entry/vdso/vma.c|  2 +-
>  arch/x86/mm/mpx.c|  2 +-
>  fs/aio.c |  2 +-
>  fs/proc/vmcore.c |  4 +-
>  fs/userfaultfd.c | 91 
> 
>  include/linux/mm.h   | 14 ---
>  include/linux/userfaultfd_k.h| 25 +++
>  include/uapi/linux/userfaultfd.h |  8 +++-
>  ipc/shm.c|  6 +--
>  kernel/exit.c|  2 +
>  mm/mmap.c| 55 ++--
>  mm/mremap.c  | 23 ++
>  mm/userfaultfd.c | 42 ++-
>  mm/util.c|  5 ++-
>  15 files changed, 215 insertions(+), 68 deletions(-)
> 
> --
Acked-by: Hillf Danton 

Re: [RFC PATCH 0/5] userfaultfd: non-cooperative: better tracking for mapping changes

[Hillf Danton]

On January 24, 2017 9:52 PM Mike Rapoport wrote: 
> Hi,
> 
> These patches try to address issues I've encountered during integration of
> userfaultfd with CRIU.
> Previously added userfaultfd events for fork(), madvise() and mremap()
> unfortunately do not cover all possible changes to a process virtual memory
> layout required for uffd monitor.
> When one or more VMAs is removed from the process mm, the external uffd
> monitor has no way to detect those changes and will attempt to fill the
> removed regions with userfaultfd_copy.
> Another problematic event is the exit() of the process. Here again, the
> external uffd monitor will try to use userfaultfd_copy, although mm owning
> the memory has already gone.
> 
> The first patch in the series is a minor cleanup and it's not strictly
> related to the rest of the series.
> 
> The patches 2 and 3 below add UFFD_EVENT_UNMAP and UFFD_EVENT_EXIT to allow
> the uffd monitor track changes in the memory layout of a process.
> 
> The patches 4 and 5 amend error codes returned by userfaultfd_copy to make
> the uffd monitor able to cope with races that might occur between delivery
> of unmap and exit events and outstanding userfaultfd_copy's.
> 
> The patches are agains current -mm tree.
> 
> Mike Rapoport (5):
>   mm: call vm_munmap in munmap syscall instead of using open coded version
>   userfaultfd: non-cooperative: add event for memory unmaps
>   userfaultfd: non-cooperative: add event for exit() notification
>   userfaultfd: mcopy_atomic: return -ENOENT when no compatible VMA found
>   userfaultfd_copy: return -ENOSPC in case mm has gone
> 
>  arch/tile/mm/elf.c   |  2 +-
>  arch/x86/entry/vdso/vma.c|  2 +-
>  arch/x86/mm/mpx.c|  2 +-
>  fs/aio.c |  2 +-
>  fs/proc/vmcore.c |  4 +-
>  fs/userfaultfd.c | 91 
> 
>  include/linux/mm.h   | 14 ---
>  include/linux/userfaultfd_k.h| 25 +++
>  include/uapi/linux/userfaultfd.h |  8 +++-
>  ipc/shm.c|  6 +--
>  kernel/exit.c|  2 +
>  mm/mmap.c| 55 ++--
>  mm/mremap.c  | 23 ++
>  mm/userfaultfd.c | 42 ++-
>  mm/util.c|  5 ++-
>  15 files changed, 215 insertions(+), 68 deletions(-)
> 
> --
Acked-by: Hillf Danton 

[RFC PATCH 0/5] userfaultfd: non-cooperative: better tracking for mapping changes

[Mike Rapoport]

Hi,

These patches try to address issues I've encountered during integration of
userfaultfd with CRIU.
Previously added userfaultfd events for fork(), madvise() and mremap()
unfortunately do not cover all possible changes to a process virtual memory
layout required for uffd monitor.
When one or more VMAs is removed from the process mm, the external uffd
monitor has no way to detect those changes and will attempt to fill the
removed regions with userfaultfd_copy.
Another problematic event is the exit() of the process. Here again, the
external uffd monitor will try to use userfaultfd_copy, although mm owning
the memory has already gone.

The first patch in the series is a minor cleanup and it's not strictly
related to the rest of the series.
 
The patches 2 and 3 below add UFFD_EVENT_UNMAP and UFFD_EVENT_EXIT to allow
the uffd monitor track changes in the memory layout of a process.

The patches 4 and 5 amend error codes returned by userfaultfd_copy to make
the uffd monitor able to cope with races that might occur between delivery
of unmap and exit events and outstanding userfaultfd_copy's.

The patches are agains current -mm tree.

Mike Rapoport (5):
  mm: call vm_munmap in munmap syscall instead of using open coded version
  userfaultfd: non-cooperative: add event for memory unmaps
  userfaultfd: non-cooperative: add event for exit() notification
  userfaultfd: mcopy_atomic: return -ENOENT when no compatible VMA found
  userfaultfd_copy: return -ENOSPC in case mm has gone

 arch/tile/mm/elf.c   |  2 +-
 arch/x86/entry/vdso/vma.c|  2 +-
 arch/x86/mm/mpx.c|  2 +-
 fs/aio.c |  2 +-
 fs/proc/vmcore.c |  4 +-
 fs/userfaultfd.c | 91 
 include/linux/mm.h   | 14 ---
 include/linux/userfaultfd_k.h| 25 +++
 include/uapi/linux/userfaultfd.h |  8 +++-
 ipc/shm.c|  6 +--
 kernel/exit.c|  2 +
 mm/mmap.c| 55 ++--
 mm/mremap.c  | 23 ++
 mm/userfaultfd.c | 42 ++-
 mm/util.c|  5 ++-
 15 files changed, 215 insertions(+), 68 deletions(-)

-- 
1.9.1

[RFC PATCH 0/5] userfaultfd: non-cooperative: better tracking for mapping changes

[Mike Rapoport]

Hi,

These patches try to address issues I've encountered during integration of
userfaultfd with CRIU.
Previously added userfaultfd events for fork(), madvise() and mremap()
unfortunately do not cover all possible changes to a process virtual memory
layout required for uffd monitor.
When one or more VMAs is removed from the process mm, the external uffd
monitor has no way to detect those changes and will attempt to fill the
removed regions with userfaultfd_copy.
Another problematic event is the exit() of the process. Here again, the
external uffd monitor will try to use userfaultfd_copy, although mm owning
the memory has already gone.

The first patch in the series is a minor cleanup and it's not strictly
related to the rest of the series.
 
The patches 2 and 3 below add UFFD_EVENT_UNMAP and UFFD_EVENT_EXIT to allow
the uffd monitor track changes in the memory layout of a process.

The patches 4 and 5 amend error codes returned by userfaultfd_copy to make
the uffd monitor able to cope with races that might occur between delivery
of unmap and exit events and outstanding userfaultfd_copy's.

The patches are agains current -mm tree.

Mike Rapoport (5):
  mm: call vm_munmap in munmap syscall instead of using open coded version
  userfaultfd: non-cooperative: add event for memory unmaps
  userfaultfd: non-cooperative: add event for exit() notification
  userfaultfd: mcopy_atomic: return -ENOENT when no compatible VMA found
  userfaultfd_copy: return -ENOSPC in case mm has gone

 arch/tile/mm/elf.c   |  2 +-
 arch/x86/entry/vdso/vma.c|  2 +-
 arch/x86/mm/mpx.c|  2 +-
 fs/aio.c |  2 +-
 fs/proc/vmcore.c |  4 +-
 fs/userfaultfd.c | 91 
 include/linux/mm.h   | 14 ---
 include/linux/userfaultfd_k.h| 25 +++
 include/uapi/linux/userfaultfd.h |  8 +++-
 ipc/shm.c|  6 +--
 kernel/exit.c|  2 +
 mm/mmap.c| 55 ++--
 mm/mremap.c  | 23 ++
 mm/userfaultfd.c | 42 ++-
 mm/util.c|  5 ++-
 15 files changed, 215 insertions(+), 68 deletions(-)

-- 
1.9.1