linux-kernel - [PATCH v3 25/27] mm/pagemap: Recognize uffd-wp bit for shmem/hugetlbfs

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Date:   Thu, 27 May 2021 16:23:40 -0400
From:   Peter Xu <peterx@...hat.com>
To:     linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:     Mike Rapoport <rppt@...ux.vnet.ibm.com>, peterx@...hat.com,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Jerome Glisse <jglisse@...hat.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Hugh Dickins <hughd@...gle.com>,
        Matthew Wilcox <willy@...radead.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>
Subject: [PATCH v3 25/27] mm/pagemap: Recognize uffd-wp bit for shmem/hugetlbfs

This requires the pagemap code to be able to recognize the newly introduced
swap special pte for uffd-wp, meanwhile the general case for hugetlb that we
recently start to support.  It should make pagemap uffd-wp support complete.

Signed-off-by: Peter Xu <peterx@...hat.com>
---
 fs/proc/task_mmu.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 9c5af77b5290..988e29fa1f00 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1389,6 +1389,8 @@ static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm,
 		flags |= PM_SWAP;
 		if (is_pfn_swap_entry(entry))
 			page = pfn_swap_entry_to_page(entry);
+	} else if (pte_swp_uffd_wp_special(pte)) {
+		flags |= PM_UFFD_WP;
 	}
 
 	if (page && !PageAnon(page))
@@ -1522,10 +1524,15 @@ static int pagemap_hugetlb_range(pte_t *ptep, unsigned long hmask,
 		if (page_mapcount(page) == 1)
 			flags |= PM_MMAP_EXCLUSIVE;
 
+		if (huge_pte_uffd_wp(pte))
+			flags |= PM_UFFD_WP;
+
 		flags |= PM_PRESENT;
 		if (pm->show_pfn)
 			frame = pte_pfn(pte) +
 				((addr & ~hmask) >> PAGE_SHIFT);
+	} else if (pte_swp_uffd_wp_special(pte)) {
+		flags |= PM_UFFD_WP;
 	}
 
 	for (; addr != end; addr += PAGE_SIZE) {
-- 
2.31.1