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authorYang Shi <shy828301@gmail.com>2022-09-07 11:01:44 -0700
committerAndrew Morton <akpm@linux-foundation.org>2022-09-26 12:14:33 -0700
commitbedf03416913d88c796288f9dca109a53608c745 (patch)
treec601eb614985fca6e3a351134e2735d47d4bc8c1 /arch
parent70cbc3cc78a997d8247b50389d37c4e1736019da (diff)
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/mm/book3s64/radix_pgtable.c9
1 files changed, 0 insertions, 9 deletions
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index 698274109c91..e712f80fe189 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -937,15 +937,6 @@ pmd_t radix__pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long addre
pmd = *pmdp;
pmd_clear(pmdp);
- /*
- * pmdp collapse_flush need to ensure that there are no parallel gup
- * walk after this call. This is needed so that we can have stable
- * page ref count when collapsing a page. We don't allow a collapse page
- * if we have gup taken on the page. We can ensure that by sending IPI
- * because gup walk happens with IRQ disabled.
- */
- serialize_against_pte_lookup(vma->vm_mm);
-
radix__flush_tlb_collapsed_pmd(vma->vm_mm, address);
return pmd;