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AJvYcCX1Y7oo43uC2S1Uj1nFuxTMbMC76IEkdQE35eaf4mvxQFXR7BC8tiWg+otRhEsdS2QM4N8hOxOc/fAJO1Q3y+rI@lists.infradead.org X-Gm-Message-State: AOJu0Yya3qhlSk0hb9vpmZbWn182pKcKHOyQQd/5QsZCsNq+i8w+KlRZ hft/8yFjyNN2zNC1uxMgdu90fejiRzrqwKCSP/G8HUVmA+Lmo4V3S7jeAZvdxzU= X-Google-Smtp-Source: AGHT+IFBw9G+gRGiVw886HN5nxLIybNKSDx7re7KNY7nJCh1bBtNFP6GTlUB4MiVeFJVy0IWyCdYMw== X-Received: by 2002:a17:90a:d987:b0:2cf:fd50:a2d8 with SMTP id 98e67ed59e1d1-2d5e997c3demr2593063a91.7.1724228447873; Wed, 21 Aug 2024 01:20:47 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([203.208.167.150]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2d5eb9049b0sm1091453a91.17.2024.08.21.01.20.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Aug 2024 01:20:47 -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 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 12/14] mm: multi-gen LRU: walk_pte_range() use pte_offset_map_maywrite_nolock() Date: Wed, 21 Aug 2024 16:18:55 +0800 Message-Id: <1bdb1ec4a30acf6b3a376f746c96236328904768.1724226076.git.zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: References: MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240821_012048_704963_C06B492C X-CRM114-Status: GOOD ( 12.51 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org In walk_pte_range(), we may modify the pte entry after holding the ptl, so convert it to using pte_offset_map_maywrite_nolock(). At this time, the write lock of mmap_lock is not held, and the pte_same() check is not performed after the ptl held, so we should get pmdval and do pmd_same() check to ensure the stability of pmd entry. Signed-off-by: Qi Zheng --- mm/vmscan.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 5dc96a843466a..a6620211f138a 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3396,8 +3396,10 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end, struct pglist_data *pgdat = lruvec_pgdat(walk->lruvec); DEFINE_MAX_SEQ(walk->lruvec); int old_gen, new_gen = lru_gen_from_seq(max_seq); + pmd_t pmdval; - pte = pte_offset_map_nolock(args->mm, pmd, start & PMD_MASK, &ptl); + pte = pte_offset_map_maywrite_nolock(args->mm, pmd, start & PMD_MASK, + &pmdval, &ptl); if (!pte) return false; if (!spin_trylock(ptl)) { @@ -3405,6 +3407,11 @@ static bool walk_pte_range(pmd_t *pmd, unsigned long start, unsigned long end, return false; } + if (unlikely(!pmd_same(pmdval, pmdp_get_lockless(pmd)))) { + pte_unmap_unlock(pte, ptl); + return false; + } + arch_enter_lazy_mmu_mode(); restart: for (i = pte_index(start), addr = start; addr != end; i++, addr += PAGE_SIZE) {