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bh=9SgMl0U05ydcYM0cFwFg6RkUkX/SVGBlhLdBNLErgqU=; b=HT/hLTzGRsnKiptOFq3qcrYA7nwWPRR+3QsgYGgGfIehJTDimPZRYNzj7KMYRkouibMERf KZiDMGJ/29DjHF/Ny9R7QMKaqqh88HHNXxlFAPvYNTt81h9fQr075F0PICGuaMsO2H5up+ dPrdwi6cHbeMbjK/xQDNihq86Lg1jvI= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-167-QqiIz_h_NguASfvv2dusNA-1; Wed, 05 Apr 2023 12:02:40 -0400 X-MC-Unique: QqiIz_h_NguASfvv2dusNA-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 27BE238221CD; Wed, 5 Apr 2023 16:02:40 +0000 (UTC) Received: from t480s.fritz.box (unknown [10.39.195.71]) by smtp.corp.redhat.com (Postfix) with ESMTP id DD0DF492C14; Wed, 5 Apr 2023 16:02:38 +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 v2 1/2] mm/userfaultfd: fix uffd-wp handling for THP migration entries Date: Wed, 5 Apr 2023 18:02:35 +0200 Message-Id: <20230405160236.587705-2-david@redhat.com> In-Reply-To: <20230405160236.587705-1-david@redhat.com> References: <20230405160236.587705-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 X-Rspam-User: X-Rspamd-Queue-Id: E40BE1C0018 X-Rspamd-Server: rspam01 X-Stat-Signature: aimupqztccd64nh1fdpiuunsgk7srx46 X-HE-Tag: 1680710562-596741 X-HE-Meta: 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 rq/Hh8ak vHuqXN9stF/w4cPg35IMYvVxWmvnPjfoukES8Fkhgjfm+6R09Tx1fpb3TDd/EWAXmQmf/scIuP6Im5GJ/8TpVO1QnL+dyiitws+qSKCvfiKYaJNuB5I3o7ne2MTu3k3yIB2CqodwohfBYkFErblHWT/krpGaAjzdbCYl9qY9Cm8YoFU84tfPOBrlLxUVNKw2NLx75CRe3A70ehKTYJl9bNxxRc/sNSg6M1kXr5YrNbLopr8Tuh1z7EdfrWg== 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") Reviewed-by: Peter Xu Cc: stable@vger.kernel.org Signed-off-by: David Hildenbrand --- 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..e3706a2b34b2 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_uffd_wp(pmdval)) + pmdswp = pmd_swp_mkuffd_wp(pmdswp); set_pmd_at(mm, address, pvmw->pmd, pmdswp); page_remove_rmap(page, vma, true); put_page(page);