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bh=wA9vrEua4SxGH0U8touKUeIrkMHHDv7b7I0B36bB+wM=; b=TKhQVo1ZNoSQ9fTDDw0QJVoAbYXsJt1gHLJI2UfUdva9S8PRE6zwOok8axJDuqOlDL878+ sVaQw+0i/OAvekZngUDkAsL285IDM8SdeFaMZ+JgdOa0L4yrS1Yklsvhzv1GiEYsHr1mkB b3LdGL6xGDYQLa42NC6q2a3aBy86fFw= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-343-mYpZFFrRMw-fpnIzPwp4dg-1; Wed, 05 Apr 2023 10:25:42 -0400 X-MC-Unique: mYpZFFrRMw-fpnIzPwp4dg-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7A9C68996E4; Wed, 5 Apr 2023 14:25:38 +0000 (UTC) Received: from t480s.fritz.box (unknown [10.39.195.71]) by smtp.corp.redhat.com (Postfix) with ESMTP id 55334400F57; Wed, 5 Apr 2023 14:25:37 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, David Hildenbrand , Andrew Morton , Peter Xu , Muhammad Usama Anjum , stable@vger.kernel.org Subject: [PATCH v1 1/2] mm/userfaultfd: fix uffd-wp handling for THP migration entries Date: Wed, 5 Apr 2023 16:25:34 +0200 Message-Id: <20230405142535.493854-2-david@redhat.com> In-Reply-To: <20230405142535.493854-1-david@redhat.com> References: <20230405142535.493854-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 4EFBBC0021 X-Stat-Signature: 45986arf1pgswnibbhzw58d4atn1tzdg X-HE-Tag: 1680704763-525160 X-HE-Meta: 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 fu7T7I9D 7P8mZxD93R7HH/71K2YkwzVOrmkupvFOmrdhuL2zv/fzbc60zbElUfreVPDyI/x9vtkSsA8DMmptw5GCQ4Py/kB/4szySUItke3NRTscqtpTnbSWZ63lF+ScDOlWIOU3zXp7qeQqbxTSWh/AKvUyoNg0ucigFsWkk4vOT3rXxRLSNr1flftmhrR3cMYyAM0yowLzLAopz3uaPVMtScRbF1hCPLYr5C0MbtZZcUEePCiY0KZJd4zR2BWovEQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Looks like what we fixed for hugetlb in commit 44f86392bdd1 ("mm/hugetlb: fix uffd-wp handling for migration entries in hugetlb_change_protection()") similarly applies to THP. Setting/clearing uffd-wp on THP migration entries is not implemented properly. Further, while removing migration PMDs considers the uffd-wp bit, inserting migration PMDs does not consider the uffd-wp bit. We have to set/clear independently of the migration entry type in change_huge_pmd() and properly copy the uffd-wp bit in set_pmd_migration_entry(). Verified using a simple reproducer that triggers migration of a THP, that the set_pmd_migration_entry() no longer loses the uffd-wp bit. Fixes: f45ec5ff16a7 ("userfaultfd: wp: support swap and page migration") Cc: stable@vger.kernel.org Signed-off-by: David Hildenbrand Reviewed-by: Peter Xu --- mm/huge_memory.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 032fb0ef9cd1..bdda4f426d58 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1838,10 +1838,10 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, if (is_swap_pmd(*pmd)) { swp_entry_t entry = pmd_to_swp_entry(*pmd); struct page *page = pfn_swap_entry_to_page(entry); + pmd_t newpmd; VM_BUG_ON(!is_pmd_migration_entry(*pmd)); if (is_writable_migration_entry(entry)) { - pmd_t newpmd; /* * A protection check is difficult so * just be safe and disable write @@ -1855,8 +1855,16 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, newpmd = pmd_swp_mksoft_dirty(newpmd); if (pmd_swp_uffd_wp(*pmd)) newpmd = pmd_swp_mkuffd_wp(newpmd); - set_pmd_at(mm, addr, pmd, newpmd); + } else { + newpmd = *pmd; } + + if (uffd_wp) + newpmd = pmd_swp_mkuffd_wp(newpmd); + else if (uffd_wp_resolve) + newpmd = pmd_swp_clear_uffd_wp(newpmd); + if (!pmd_same(*pmd, newpmd)) + set_pmd_at(mm, addr, pmd, newpmd); goto unlock; } #endif @@ -3251,6 +3259,8 @@ int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, pmdswp = swp_entry_to_pmd(entry); if (pmd_soft_dirty(pmdval)) pmdswp = pmd_swp_mksoft_dirty(pmdswp); + if (pmd_swp_uffd_wp(*pvmw->pmd)) + pmdswp = pmd_swp_mkuffd_wp(pmdswp); set_pmd_at(mm, address, pvmw->pmd, pmdswp); page_remove_rmap(page, vma, true); put_page(page);