powerpc/64s/radix: don't need to broadcast IPI for radix pmd collapse flush
authorYang Shi <shy828301@gmail.com>
Wed, 7 Sep 2022 18:01:44 +0000 (11:01 -0700)
committerAndrew Morton <akpm@linux-foundation.org>
Mon, 26 Sep 2022 19:14:33 +0000 (12:14 -0700)
commitbedf03416913d88c796288f9dca109a53608c745
treec601eb614985fca6e3a351134e2735d47d4bc8c1
parent70cbc3cc78a997d8247b50389d37c4e1736019da
powerpc/64s/radix: don't need to broadcast IPI for radix pmd collapse flush

The IPI broadcast is used to serialize against fast-GUP, but fast-GUP will
move to use RCU instead of disabling local interrupts in fast-GUP.  Using
an IPI is the old-styled way of serializing against fast-GUP although it
still works as expected now.

And fast-GUP now fixed the potential race with THP collapse by checking
whether PMD is changed or not.  So IPI broadcast in radix pmd collapse
flush is not necessary anymore.  But it is still needed for hash TLB.

Link: https://lkml.kernel.org/r/20220907180144.555485-2-shy828301@gmail.com
Suggested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
arch/powerpc/mm/book3s64/radix_pgtable.c