Messages in this thread | | | Date | Thu, 16 Jun 2022 10:27:02 +0800 | Subject | Re: [RFC PATCHES 1/2] iommu: Add RCU-protected page free support | From | Baolu Lu <> |
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On 2022/6/15 23:40, Jason Gunthorpe wrote: > On Fri, Jun 10, 2022 at 01:37:20PM +0800, Baolu Lu wrote: >> On 2022/6/9 20:49, Jason Gunthorpe wrote: >>>> +void iommu_free_pgtbl_pages(struct iommu_domain *domain, >>>> + struct list_head *pages) >>>> +{ >>>> + struct page *page, *next; >>>> + >>>> + if (!domain->concurrent_traversal) { >>>> + put_pages_list(pages); >>>> + return; >>>> + } >>>> + >>>> + list_for_each_entry_safe(page, next, pages, lru) { >>>> + list_del(&page->lru); >>>> + call_rcu(&page->rcu_head, pgtble_page_free_rcu); >>>> + } >>> It seems OK, but I wonder if there is benifit to using >>> put_pages_list() from the rcu callback >> >> The price is that we need to allocate a "struct list_head" and free it >> in the rcu callback as well. Currently the list_head is sitting in the >> stack. > > You'd have to use a different struct page layout so that the list_head > was in the struct page and didn't overlap with the rcu_head
Okay, let me head this direction in the next version.
Best regards, baolu
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