linux-stable.git/mm/userfaultfd.c, branch v6.4.3

userfaultfd: use helper function range_in_vma()

2023-04-21T21:52:02+00:00

We can use range_in_vma() to check if dst_start, dst_start + len are
within the dst_vma range.  Minor readability improvement.

Link: https://lkml.kernel.org/r/20230417003919.930515-1-zhangpeng362@huawei.com
Signed-off-by: ZhangPeng 
Reviewed-by: David Hildenbrand 
Cc: Kefeng Wang 
Cc: Mike Kravetz 
Cc: Nanyong Sun 
Signed-off-by: Andrew Morton

userfaultfd: convert mfill_atomic() to use a folio

2023-04-18T23:29:55+00:00

Convert mfill_atomic_pte_copy(), shmem_mfill_atomic_pte() and
mfill_atomic_pte() to take in a folio pointer.

Convert mfill_atomic() to use a folio.  Convert page_kaddr to kaddr in
mfill_atomic().

Link: https://lkml.kernel.org/r/20230410133932.32288-7-zhangpeng362@huawei.com
Signed-off-by: ZhangPeng 
Reviewed-by: Mike Kravetz 
Cc: Kefeng Wang 
Cc: Matthew Wilcox 
Cc: Muchun Song 
Cc: Nanyong Sun 
Cc: Sidhartha Kumar 
Cc: Vishal Moola (Oracle) 
Signed-off-by: Andrew Morton

userfaultfd: convert mfill_atomic_hugetlb() to use a folio

2023-04-18T23:29:55+00:00

Convert hugetlb_mfill_atomic_pte() to take in a folio pointer instead of
a page pointer.

Convert mfill_atomic_hugetlb() to use a folio.

Link: https://lkml.kernel.org/r/20230410133932.32288-5-zhangpeng362@huawei.com
Signed-off-by: ZhangPeng 
Reviewed-by: Sidhartha Kumar 
Reviewed-by: Mike Kravetz 
Cc: Kefeng Wang 
Cc: Matthew Wilcox 
Cc: Muchun Song 
Cc: Nanyong Sun 
Cc: Vishal Moola (Oracle) 
Signed-off-by: Andrew Morton

userfaultfd: convert copy_huge_page_from_user() to copy_folio_from_user()

2023-04-18T23:29:55+00:00

Replace copy_huge_page_from_user() with copy_folio_from_user(). 
copy_folio_from_user() does the same as copy_huge_page_from_user(), but
takes in a folio instead of a page.

Convert page_kaddr to kaddr in copy_folio_from_user() to do indenting
cleanup.

Link: https://lkml.kernel.org/r/20230410133932.32288-4-zhangpeng362@huawei.com
Signed-off-by: ZhangPeng 
Reviewed-by: Sidhartha Kumar 
Reviewed-by: Mike Kravetz 
Cc: Kefeng Wang 
Cc: Matthew Wilcox 
Cc: Muchun Song 
Cc: Nanyong Sun 
Cc: Vishal Moola (Oracle) 
Signed-off-by: Andrew Morton

userfaultfd: convert mfill_atomic_pte_copy() to use a folio

2023-04-18T23:29:54+00:00

Patch series "userfaultfd: convert userfaultfd functions to use folios",
v6.

This patch series converts several userfaultfd functions to use folios.


This patch (of 6):

Call vma_alloc_folio() directly instead of alloc_page_vma() and convert
page_kaddr to kaddr in mfill_atomic_pte_copy().  Removes several calls to
compound_head().

Link: https://lkml.kernel.org/r/20230410133932.32288-1-zhangpeng362@huawei.com
Link: https://lkml.kernel.org/r/20230410133932.32288-2-zhangpeng362@huawei.com
Signed-off-by: ZhangPeng 
Reviewed-by: Sidhartha Kumar 
Reviewed-by: Mike Kravetz 
Cc: Kefeng Wang 
Cc: Matthew Wilcox 
Cc: Muchun Song 
Cc: Nanyong Sun 
Cc: Vishal Moola (Oracle) 
Signed-off-by: Andrew Morton

mm: userfaultfd: add UFFDIO_CONTINUE_MODE_WP to install WP PTEs

2023-04-06T02:42:48+00:00

UFFDIO_COPY already has UFFDIO_COPY_MODE_WP, so when installing a new PTE
to resolve a missing fault, one can install a write-protected one.  This
is useful when using UFFDIO_REGISTER_MODE_{MISSING,WP} in combination.

This was motivated by testing HugeTLB HGM [1], and in particular its
interaction with userfaultfd features.  Existing userfaultfd code supports
using WP and MINOR modes together (i.e.  you can register an area with
both enabled), but without this CONTINUE flag the combination is in
practice unusable.

So, add an analogous UFFDIO_CONTINUE_MODE_WP, which does the same thing as
UFFDIO_COPY_MODE_WP, but for *minor* faults.

Update the selftest to do some very basic exercising of the new flag.

Update Documentation/ to describe how these flags are used (neither the
COPY nor the new CONTINUE versions of this mode flag were described there
before).

[1]: https://patchwork.kernel.org/project/linux-mm/cover/20230218002819.1486479-1-jthoughton@google.com/

Link: https://lkml.kernel.org/r/20230314221250.682452-5-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen 
Acked-by: Peter Xu 
Acked-by: Mike Rapoport (IBM) 
Cc: Al Viro 
Cc: Hugh Dickins 
Cc: Jan Kara 
Cc: Liam R. Howlett 
Cc: Matthew Wilcox (Oracle) 
Cc: Mike Kravetz 
Cc: Muchun Song 
Cc: Nadav Amit 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton

mm: userfaultfd: combine 'mode' and 'wp_copy' arguments

2023-04-06T02:42:48+00:00

Many userfaultfd ioctl functions take both a 'mode' and a 'wp_copy'
argument.  In future commits we plan to plumb the flags through to more
places, so we'd be proliferating the very long argument list even further.

Let's take the time to simplify the argument list.  Combine the two
arguments into one - and generalize, so when we add more flags in the
future, it doesn't imply more function arguments.

Since the modes (copy, zeropage, continue) are mutually exclusive, store
them as an integer value (0, 1, 2) in the low bits.  Place combine-able
flag bits in the high bits.

This is quite similar to an earlier patch proposed by Nadav Amit
("userfaultfd: introduce uffd_flags" [1]).  The main difference is that
patch only handled flags, whereas this patch *also* combines the "mode"
argument into the same type to shorten the argument list.

[1]: https://lore.kernel.org/all/20220619233449.181323-2-namit@vmware.com/

Link: https://lkml.kernel.org/r/20230314221250.682452-4-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen 
Acked-by: James Houghton 
Acked-by: Peter Xu 
Acked-by: Mike Rapoport (IBM) 
Cc: Al Viro 
Cc: Hugh Dickins 
Cc: Jan Kara 
Cc: Liam R. Howlett 
Cc: Matthew Wilcox (Oracle) 
Cc: Mike Kravetz 
Cc: Muchun Song 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton

mm: userfaultfd: don't pass around both mm and vma

2023-04-06T02:42:47+00:00

Quite a few userfaultfd functions took both mm and vma pointers as
arguments.  Since the mm is trivially accessible via vma->vm_mm, there's
no reason to pass both; it just needlessly extends the already long
argument list.

Get rid of the mm pointer, where possible, to shorten the argument list.

Link: https://lkml.kernel.org/r/20230314221250.682452-3-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen 
Acked-by: Peter Xu 
Acked-by: Mike Rapoport (IBM) 
Cc: Al Viro 
Cc: Hugh Dickins 
Cc: James Houghton 
Cc: Jan Kara 
Cc: Liam R. Howlett 
Cc: Matthew Wilcox (Oracle) 
Cc: Mike Kravetz 
Cc: Muchun Song 
Cc: Nadav Amit 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton

mm: userfaultfd: rename functions for clarity + consistency

2023-04-06T02:42:47+00:00

Patch series "mm: userfaultfd: refactor and add UFFDIO_CONTINUE_MODE_WP",
v5.

- Commits 1-3 refactor userfaultfd ioctl code without behavior changes, with the
  main goal of improving consistency and reducing the number of function args.

- Commit 4 adds UFFDIO_CONTINUE_MODE_WP.


This patch (of 4):

The basic problem is, over time we've added new userfaultfd ioctls, and
we've refactored the code so functions which used to handle only one case
are now re-used to deal with several cases.  While this happened, we
didn't bother to rename the functions.

Similarly, as we added new functions, we cargo-culted pieces of the
now-inconsistent naming scheme, so those functions too ended up with names
that don't make a lot of sense.

A key point here is, "copy" in most userfaultfd code refers specifically
to UFFDIO_COPY, where we allocate a new page and copy its contents from
userspace.  There are many functions with "copy" in the name that don't
actually do this (at least in some cases).

So, rename things into a consistent scheme.  The high level idea is that
the call stack for userfaultfd ioctls becomes:

userfaultfd_ioctl
  -> userfaultfd_(particular ioctl)
    -> mfill_atomic_(particular kind of fill operation)
      -> mfill_atomic    /* loops over pages in range */
        -> mfill_atomic_pte    /* deals with single pages */
          -> mfill_atomic_pte_(particular kind of fill operation)
            -> mfill_atomic_install_pte

There are of course some special cases (shmem, hugetlb), but this is the
general structure which all function names now adhere to.

Link: https://lkml.kernel.org/r/20230314221250.682452-1-axelrasmussen@google.com
Link: https://lkml.kernel.org/r/20230314221250.682452-2-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen 
Acked-by: Peter Xu 
Acked-by: Mike Rapoport (IBM) 
Cc: Al Viro 
Cc: Hugh Dickins 
Cc: James Houghton 
Cc: Jan Kara 
Cc: Liam R. Howlett 
Cc: Matthew Wilcox (Oracle) 
Cc: Mike Kravetz 
Cc: Muchun Song 
Cc: Nadav Amit 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton

mm/userfaultfd: support WP on multiple VMAs

2023-03-28T23:20:07+00:00

mwriteprotect_range() errors out if [start, end) doesn't fall in one VMA. 
We are facing a use case where multiple VMAs are present in one range of
interest.  For example, the following pseudocode reproduces the error
which we are trying to fix:

- Allocate memory of size 16 pages with PROT_NONE with mmap
- Register userfaultfd
- Change protection of the first half (1 to 8 pages) of memory to
  PROT_READ | PROT_WRITE. This breaks the memory area in two VMAs.
- Now UFFDIO_WRITEPROTECT_MODE_WP on the whole memory of 16 pages errors
  out.

This is a simple use case where user may or may not know if the memory
area has been divided into multiple VMAs.

We need an implementation which doesn't disrupt the already present users.
So keeping things simple, stop going over all the VMAs if any one of the
VMA hasn't been registered in WP mode.  While at it, remove the un-needed
error check as well.

[akpm@linux-foundation.org: s/VM_WARN_ON_ONCE/VM_WARN_ONCE/ to fix build]
Link: https://lkml.kernel.org/r/20230217105558.832710-1-usama.anjum@collabora.com
Signed-off-by: Muhammad Usama Anjum 
Acked-by: Peter Xu 
Acked-by: David Hildenbrand 
Reported-by: Paul Gofman 
Signed-off-by: Andrew Morton