linux-kernel - [PATCH v6 20/23] mm/pagemap: Recognize uffd-wp bit for shmem/hugetlbfs

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Message-Id: <20211115080323.75209-1-peterx@redhat.com>
Date:   Mon, 15 Nov 2021 16:03:23 +0800
From:   Peter Xu <peterx@...hat.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     Nadav Amit <nadav.amit@...il.com>, peterx@...hat.com,
        Alistair Popple <apopple@...dia.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Matthew Wilcox <willy@...radead.org>,
        Jerome Glisse <jglisse@...hat.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        David Hildenbrand <david@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Hugh Dickins <hughd@...gle.com>
Subject: [PATCH v6 20/23] 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 | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index ad667dbc96f5..5d2f73b2e63d 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1390,6 +1390,12 @@ 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);
+		if (is_pte_marker_entry(entry)) {
+			pte_marker marker = pte_marker_get(entry);
+
+			if (marker & PTE_MARKER_UFFD_WP)
+				flags |= PM_UFFD_WP;
+		}
 	}
 
 	if (page && !PageAnon(page))
@@ -1523,10 +1529,15 @@ 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_any(pte)) {
+		flags |= PM_UFFD_WP;
 	}
 
 	for (; addr != end; addr += PAGE_SIZE) {
-- 
2.32.0