Re: [PATCH v3] mm/migrate.c: Rework migration_entry_wait() to not take a pageref
flat view
From: Matthew Wilcox <willy@infradead.org>
Date: 2021-11-16 01:26:37
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On Mon, Nov 15, 2021 at 09:52:22PM +1100, Alistair Popple wrote:
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+#ifdef CONFIG_MIGRATION +/** + * migration_entry_wait_on_locked - Wait for a migration entry to be removed + * @page: page referenced by the migration entry.
This should be @folio (you can test by running 'make htmldocs', or even 'make W=1'
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+ * @ptep: mapped pte pointer. This function will return with the ptep unmapped. + * @ptl: already locked ptl. This function will drop the lock. + * + * Wait for a migration entry referencing the given page to be removed. This is + * equivalent to put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE) except + * this can be called without taking a reference on the page. Instead this + * should be called while holding the ptl for the migration entry referencing + * the page.
The tool won't tell you to update these page references to be folio references ... so I will ;-)
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+++ b/mm/migrate.c@@ -305,15 +305,7 @@ void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep, page = pfn_swap_entry_to_page(entry); page = compound_head(page);
I think this whole function should be folio-based. That is: - struct page *page; + struct folio *folio; and folio = page_folio(pfn_swap_entry_to_page(entry));