The patch titled
Subject: secretmem/gup: don't check if page is secretmem without reference
has been added to the -mm tree. Its filename is
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-2.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-2.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-2.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Subject: secretmem/gup: don't check if page is secretmem without reference
The check in gup_pte_range() whether a page belongs to a secretmem mapping
is performed before grabbing the page reference.
To avoid potential race move the check after try_grab_compound_head().
Link: https://lkml.kernel.org/r/20210420150049.14031-2-rppt@xxxxxxxxxx
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
--- a/mm/gup.c~mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-2
+++ a/mm/gup.c
@@ -2080,13 +2080,15 @@ static int gup_pte_range(pmd_t pmd, unsi
VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
page = pte_page(pte);
- if (page_is_secretmem(page))
- goto pte_unmap;
-
head = try_grab_compound_head(page, 1, flags);
if (!head)
goto pte_unmap;
+ if (unlikely(page_is_secretmem(page))) {
+ put_compound_head(head, 1, flags);
+ goto pte_unmap;
+ }
+
if (unlikely(pte_val(pte) != pte_val(*ptep))) {
put_compound_head(head, 1, flags);
goto pte_unmap;
_
Patches currently in -mm which might be from rppt@xxxxxxxxxxxxx are
mm-cma-rename-pf_memalloc_nocma-to-pf_memalloc_pin-fix.patch
mmap-make-mlock_future_check-global.patch
riscv-kconfig-make-direct-map-manipulation-options-depend-on-mmu.patch
set_memory-allow-set_direct_map__noflush-for-multiple-pages.patch
set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled.patch
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas.patch
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix.patch
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix-2.patch
pm-hibernate-disable-when-there-are-active-secretmem-users.patch
arch-mm-wire-up-memfd_secret-system-call-where-relevant.patch
arch-mm-wire-up-memfd_secret-system-call-where-relevant-fix.patch
secretmem-test-add-basic-selftest-for-memfd_secret2.patch
secretmem-test-add-basic-selftest-for-memfd_secret2-fix.patch
secretmem-optimize-page_is_secretmem.patch
