On 11/26/24 06:04, Hyeonggon Yoo wrote: > On Tue, Nov 26, 2024 at 7:38 AM Matthew Wilcox (Oracle) > <willy@xxxxxxxxxxxxx> wrote: >> >> Slab does not need to use the page refcount at all, and it can avoid >> an atomic operation on page free. Hugetlb wants to delay setting the >> refcount until it has assembled a complete gigantic page. We already >> have the ability to freeze a page (safely reduce its reference count to >> 0), so this patchset adds APIs to allocate and free pages which are in >> a frozen state. > > [+Cc Vlastimil] > > I think with this patchset, we can finally remove the memory barriers used > in isolate_movable_page(), alloc_slab_page(), and __free_slab(), > because folio_get_nontail_page() should fail for frozen pages? Thanks for the heads-up! > for reference, the patch that introduced the memory barrier: > https://lore.kernel.org/linux-mm/Y20BRJmRzRVMzoJw@hyeyoo Are you going to sent the necessary patch on top of this series then? :) We could route it via -mm to avoid waiting a cycle or needing extra synchronization. It's not a pure slab change anyway... Thanks, Vlastimil > Best, > Hyeonggon
