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authorAxel Rasmussen <axelrasmussen@google.com>2021-06-30 18:49:20 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-06-30 20:47:27 -0700
commitc949b097ef2e332fa90708127c972b823fb58ec1 (patch)
tree1c8c7288f61aaf1dc64df90f8239bb73a7a4c050 /mm/memory.c
parent3460f6e5c1ed94c2ab7c1ccc032a5bebd88deaa7 (diff)
downloadlinux-c949b097ef2e332fa90708127c972b823fb58ec1.tar.bz2
userfaultfd/shmem: support minor fault registration for shmem
This patch allows shmem-backed VMAs to be registered for minor faults. Minor faults are appropriately relayed to userspace in the fault path, for VMAs with the relevant flag. This commit doesn't hook up the UFFDIO_CONTINUE ioctl for shmem-backed minor faults, though, so userspace doesn't yet have a way to resolve such faults. Because of this, we also don't yet advertise this as a supported feature. That will be done in a separate commit when the feature is fully implemented. Link: https://lkml.kernel.org/r/20210503180737.2487560-4-axelrasmussen@google.com Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> Acked-by: Peter Xu <peterx@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Upton <oupton@google.com> Cc: Shaohua Li <shli@fb.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Wang Qing <wangqing@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 07a71a016c18..b535a1d0317d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4026,9 +4026,11 @@ static vm_fault_t do_read_fault(struct vm_fault *vmf)
* something).
*/
if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
- ret = do_fault_around(vmf);
- if (ret)
- return ret;
+ if (likely(!userfaultfd_minor(vmf->vma))) {
+ ret = do_fault_around(vmf);
+ if (ret)
+ return ret;
+ }
}
ret = __do_fault(vmf);