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AJvYcCXA2YarYqt5dwFsOeZGI50PWv8JlC13YryIcR/SbxEDzRkTof+ECk3zUcfOlC0MBEwYKGx1Xj270Q==@kvack.org X-Gm-Message-State: AOJu0YwK4yfaFrYu+lesPRsj3iTtAGG8gTkTjJfIcwTCfs0MxLHIs1zZ akEje7m9i0v7aRyQSHSvvCnPSKw0VAi9kAvcLM9XsDqOt/RppGBo0O9xIphG7W8= X-Google-Smtp-Source: AGHT+IH3dTXEnimLAtKAfnTveP36n8fQueYjLUMvugh9RpWMjyLI+ldrjyQ+VF2Ub3qToXnGQhbMbg== X-Received: by 2002:a05:6808:3847:b0:3d6:2b12:7dc0 with SMTP id 5614622812f47-3de22ff6ae0mr1325714b6e.20.1724310890896; Thu, 22 Aug 2024 00:14:50 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([240e:473:c90:f96:d029:ea8a:4e6d:d272]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-7cd9ac994a3sm695095a12.16.2024.08.22.00.14.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Aug 2024 00:14:50 -0700 (PDT) From: Qi Zheng To: david@redhat.com, hughd@google.com, willy@infradead.org, muchun.song@linux.dev, vbabka@kernel.org, akpm@linux-foundation.org, rppt@kernel.org, vishal.moola@gmail.com, peterx@redhat.com, ryan.roberts@arm.com, christophe.leroy2@cs-soprasteria.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, Qi Zheng Subject: [PATCH v2 11/14] mm: userfaultfd: move_pages_pte() use pte_offset_map_rw_nolock() Date: Thu, 22 Aug 2024 15:13:26 +0800 Message-Id: X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: References: MIME-Version: 1.0 X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: D200B18000F X-Stat-Signature: yqhf4z4ayofpbh6kbeit75xifxnkbb1c X-Rspam-User: X-HE-Tag: 1724310891-619771 X-HE-Meta: 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 88gasp7N JtQqh2JwAv3DIm/Hn/qXyLJj7ppMtDG7awqLjMEffHYb1WA7WIMTRWfSkS3QWwp3AbKkFwZCCX3m029dXwOPB1ADQjzVwsKeZNQ4UFm7FnKav8ja1x4an/k0mK6Fj+Tglkj4zq5CxCeYPAzMquAbP6gVpQWHTduDtn37flljtjovvOaI5ldYGlpZmKabzHbiiWW1QC+d8jasOzWcTOPBr53ik2qYZ2FFYAaf/CHE2EArQCzbXxM3/I1WxroCpd9Slc2rwYdTICGxpjkNvH9LJS/7jy/7/WQ40d90FcyZNQx9e/0Lrpug6ZrziwXFkOQ4fvoWehjCoOPWyMQbkaq5Qpwo3yJqTnloWXL9GLp9LNt7j01eBukUMQqjkeKtVxCV+jm7NcMK7U3AmSz+HX0n6NxpDIXPyvMHQJiS5/y8DqHRMob8eC+0LhthvmY5BALBtImeZ 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: List-Subscribe: List-Unsubscribe: In move_pages_pte(), we may modify the dst_pte and src_pte after acquiring the ptl, so convert it to using pte_offset_map_rw_nolock(). But since we already do the pte_same() check, there is no need to get pmdval to do pmd_same() check, just pass a dummy variable to it. Signed-off-by: Qi Zheng --- mm/userfaultfd.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 6ef42d9cd482e..414ee744257b7 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -1135,7 +1135,7 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, spinlock_t *src_ptl, *dst_ptl; pte_t *src_pte = NULL; pte_t *dst_pte = NULL; - + pmd_t dummy_pmdval; struct folio *src_folio = NULL; struct anon_vma *src_anon_vma = NULL; struct mmu_notifier_range range; @@ -1146,7 +1146,14 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, src_addr, src_addr + PAGE_SIZE); mmu_notifier_invalidate_range_start(&range); retry: - dst_pte = pte_offset_map_nolock(mm, dst_pmd, dst_addr, &dst_ptl); + /* + * Use the maywrite version to indicate that dst_pte will be modified, + * but since we will use pte_same() to detect the change of the pte + * entry, there is no need to get pmdval, so just pass a dummy variable + * to it. + */ + dst_pte = pte_offset_map_rw_nolock(mm, dst_pmd, dst_addr, &dummy_pmdval, + &dst_ptl); /* Retry if a huge pmd materialized from under us */ if (unlikely(!dst_pte)) { @@ -1154,7 +1161,9 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, goto out; } - src_pte = pte_offset_map_nolock(mm, src_pmd, src_addr, &src_ptl); + /* same as dst_pte */ + src_pte = pte_offset_map_rw_nolock(mm, src_pmd, src_addr, &dummy_pmdval, + &src_ptl); /* * We held the mmap_lock for reading so MADV_DONTNEED