linux-kernel - [PATCH v8 20/23] mm/pagemap: Recognize uffd-wp bit for shmem/hugetlbfs

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Date:   Mon,  4 Apr 2022 21:49:23 -0400
From:   Peter Xu <peterx@...hat.com>
To:     linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:     Mike Kravetz <mike.kravetz@...cle.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Matthew Wilcox <willy@...radead.org>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Hugh Dickins <hughd@...gle.com>,
        Jerome Glisse <jglisse@...hat.com>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Alistair Popple <apopple@...dia.com>, peterx@...hat.com
Subject: [PATCH v8 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 | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index f46060eb91b5..194dfd7abf2b 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1421,6 +1421,8 @@ static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm,
 		migration = is_migration_entry(entry);
 		if (is_pfn_swap_entry(entry))
 			page = pfn_swap_entry_to_page(entry);
+		if (pte_marker_entry_uffd_wp(entry))
+			flags |= PM_UFFD_WP;
 	}
 
 	if (page && !PageAnon(page))
@@ -1556,10 +1558,15 @@ 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