On 24.01.23 01:51, Kirill A. Shutemov wrote:
On Mon, Jan 23, 2023 at 12:07:05PM +0100, David Hildenbrand wrote:
commit bedf03416913d88c796288f9dca109a53608c745
Author: Yang Shi <shy828301@xxxxxxxxx>
Date: Wed Sep 7 11:01:44 2022 -0700
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.
Okay. But I think tlb_remove_table_sync_one() belongs inside
pmdp_collapse_flush(). Collapsing pmd table into huge page without
serialization is a bug. They should not be separate.
Agreed. But I wonder if it should be moved into a generic
pmdp_collapse_flush(), that calls an arch specific __pmdp_collapse_flush().
Um? There's no __pmdp_collapse_flush().
Did I imply that there is already one? ;)
--
Thanks,
David / dhildenb
