[PATCH v2 0/3] mm/secretmem: one fix and one refactoring

David Hildenbrand
2024-03-26T14:32:40Z

Patch #1 fixes a GUP-fast issue, whereby we might succeed in pinning
secretmem folios. Patch #2 extends the memfd_secret selftest to cover
that case. Patch #3 removes folio_is_secretmem() and instead lets
folio_fast_pin_allowed() cover that case as well.

With this series, the reproducer (+selftests) works as expected. To
test patch #3, the gup_longterm test does exactly what we need, and
keeps on working as expected.

Without the fix:
TAP version 13
1..6
ok 1 mlock limit is respected
ok 2 file IO is blocked as expected
not ok 3 vmsplice: unexpected memory access with fresh page
ok 4 vmsplice is blocked as expected with existing page
ok 5 process_vm_read is blocked as expected
ok 6 ptrace is blocked as expected
# Totals: pass:5 fail:1 xfail:0 xpass:0 skip:0 error:0

With the fix:
TAP version 13
1..6
ok 1 mlock limit is respected
ok 2 file IO is blocked as expected
ok 3 vmsplice is blocked as expected with fresh page
ok 4 vmsplice is blocked as expected with existing page
ok 5 process_vm_read is blocked as expected
ok 6 ptrace is blocked as expected
# Totals: pass:6 fail:0 xfail:0 xpass:0 skip:0 error:0

v1 -> v2:
* "mm/secretmem: fix GUP-fast succeeding on secretmem folios"
-> Drop the LRU check completely
-> Rephrase patch description
-> (Dropped RB from Mike)
* "selftests/memfd_secret: add vmsplice() test"
-> Add test with fresh+existing page
-> Change pass/fail message
-> Rephrase patch description
-> (Dropped RB from Mike)
* "mm: merge folio_is_secretmem() and folio_fast_pin_allowed() into
gup_fast_folio_allowed()"
-> Adjust to dropped LRU check
-> Rename folio_fast_pin_allowed() to gup_fast_folio_allowed()
-> Rephrase patch description
-> Add RB from Mike

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: xingwei lee <xrivendell7@gmail.com>
Cc: yue sun <samsun1006219@gmail.com>

David Hildenbrand (3):
mm/secretmem: fix GUP-fast succeeding on secretmem folios
selftests/memfd_secret: add vmsplice() test
mm: merge folio_is_secretmem() and folio_fast_pin_allowed() into
gup_fast_folio_allowed()

include/linux/secretmem.h | 21 +---------
mm/gup.c | 48 ++++++++++++---------
tools/testing/selftests/mm/memfd_secret.c | 51 ++++++++++++++++++++++-
3 files changed, 79 insertions(+), 41 deletions(-)

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2.43.2