+ mm-gup-assert-that-the-mmap-lock-is-held-in-__get_user_pages.patch added to -mm tree

+ mm-gup-assert-that-the-mmap-lock-is-held-in-__get_user_pages.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm/gup: assert that the mmap lock is held in __get_user_pages()
has been added to the -mm tree.  Its filename is
     mm-gup-assert-that-the-mmap-lock-is-held-in-__get_user_pages.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-gup-assert-that-the-mmap-lock-is-held-in-__get_user_pages.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-assert-that-the-mmap-lock-is-held-in-__get_user_pages.patch

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------------------------------------------------------
From: Jann Horn <jannh@google.com>
Subject: mm/gup: assert that the mmap lock is held in __get_user_pages()

After having cleaned up all GUP callers (except for the atomisp staging
driver, which currently gets mmap locking completely wrong [1]) to always
ensure that they hold the mmap lock when calling into GUP (unless the mm
is not yet globally visible), add an assertion to make sure it stays that
way going forward.

[1] https://lore.kernel.org/lkml/CAG48ez3tZAb9JVhw4T5e-i=h2_DUZxfNRTDsagSRCVazNXx5qA@mail.gmail.com/

Link: https://lkml.kernel.org/r/CAG48ez1GM==OnHpS=ghqZNJPn02FCDUEHc7GQmGRMXUD_aKudg@mail.gmail.com
Signed-off-by: Jann Horn <jannh@google.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Michel Lespinasse <walken@google.com>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/gup.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/mm/gup.c~mm-gup-assert-that-the-mmap-lock-is-held-in-__get_user_pages
+++ a/mm/gup.c
@@ -1027,6 +1027,8 @@ static long __get_user_pages(struct mm_s
 	struct vm_area_struct *vma = NULL;
 	struct follow_page_context ctx = { NULL };
 
+	mmap_assert_locked(mm);
+
 	if (!nr_pages)
 		return 0;
 
_

Patches currently in -mm which might be from jannh@google.com are

mm-mmu_notifier-fix-mmget-assert-in-__mmu_interval_notifier_insert.patch
binfmt_elf_fdpic-stop-using-dump_emit-on-user-pointers-on-mmu.patch
coredump-let-dump_emit-bail-out-on-short-writes.patch
coredump-refactor-page-range-dumping-into-common-helper.patch
coredump-rework-elf-elf_fdpic-vma_dump_size-into-common-helper.patch
binfmt_elf-binfmt_elf_fdpic-use-a-vma-list-snapshot.patch
mm-gup-take-mmap_lock-in-get_dump_page.patch
mm-remove-the-now-unnecessary-mmget_still_valid-hack.patch
mm-gup_benchmark-take-the-mmap-lock-around-gup.patch
binfmt_elf-take-the-mmap-lock-around-find_extend_vma.patch
mmap-locking-api-dont-check-locking-if-the-mm-isnt-live-yet.patch
mm-gup-assert-that-the-mmap-lock-is-held-in-__get_user_pages.patch