On 27.03.24 15:53, Matthew Wilcox wrote:
On Sat, Mar 23, 2024 at 12:41:36AM +1300, Barry Song wrote:Commit d0637c505f8a1 ("arm64: enable THP_SWAP for arm64") brings up THP_SWAP on ARM64, but it doesn't enable THP_SWP on hardware with MTE as the MTE code works with the assumption tags save/restore is always handling a folio with only one page. The limitation should be removed as more and more ARM64 SoCs have this feature. Co-existence of MTE and THP_SWAP becomes more and more important. This patch makes MTE tags saving support large folios, then we don't need to split large folios into base pages for swapping out on ARM64 SoCs with MTE any more.Can we go further than this patch and only support PG_mte_tagged and PG_mte_lock on folio->flags instead of page->flags? We're down to using
I think we discussed that already and what I learned is that it "gets a bit complicated". But I'm hoping we can get that discussion started again.
page->flags for these two MTE bits, a whole lot of s390 junk, PG_hwpoison, PG_head, PG_anon_exclusive and Zone/Section/Node/KASAN/last_cpupid.
... just like PG_anon_exclusive "gets a bit complicated". Well, I think I might have finally found a way to make it work, I'll only have to uglify fork() a bit.
-- Cheers, David / dhildenb
