Commit 9977f0f1 authored by Gerald Schaefer's avatar Gerald Schaefer Committed by Linus Torvalds
Browse files

mm: don't overwrite mm->def_flags in do_mlockall() 



With commit 8e72033f ("thp: make MADV_HUGEPAGE check for
mm->def_flags") the VM_NOHUGEPAGE flag may be set on s390 in
mm->def_flags for certain processes, to prevent future thp mappings.
This would be overwritten by do_mlockall(), which sets it back to 0 with
an optional VM_LOCKED flag set.

To fix this, instead of overwriting mm->def_flags in do_mlockall(), only
the VM_LOCKED flag should be set or cleared.

Signed-off-by: default avatarGerald Schaefer <gerald.schaefer@de.ibm.com>
Reported-by: default avatarVivek Goyal <vgoyal@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3399cfb5

mm/mlock.c

+3 −3
Original line number Diff line number Diff line
@@ -517,11 +517,11 @@ SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len) 
static int do_mlockall(int flags)

{

	struct vm_area_struct * vma, * prev = NULL;

	unsigned int def_flags = 0;



	if (flags & MCL_FUTURE)

		def_flags = VM_LOCKED;

	current->mm->def_flags = def_flags;

		current->mm->def_flags |= VM_LOCKED;

	else

		current->mm->def_flags &= ~VM_LOCKED;

	if (flags == MCL_FUTURE)

		goto out;

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