Messages in this thread | | | Date | Sat, 27 May 2023 04:18:07 +0100 | From | Matthew Wilcox <> | Subject | Re: [PATCH v4] mm, compaction: Skip all non-migratable pages during scan |
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On Fri, May 26, 2023 at 07:11:05PM -0700, John Hubbard wrote: > > So any user with 1024 processes can fragment physical memory? :/ > > > > Sorry, I'd like to minimize the usage of folio_maybe_dma_pinned(). > > I was actually thinking that we should minimize any more cases of > fragile mapcount and refcount comparison, which then leads to > Matthew's approach here!
I was wondering if we shouldn't make folio_maybe_dma_pinned() a little more accurate. eg:
if (folio_test_large(folio)) return atomic_read(&folio->_pincount) > 0; return (unsigned)(folio_ref_count(folio) - folio_mapcount(folio)) >= GUP_PIN_COUNTING_BIAS;
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