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AJvYcCXzg1t8V+90XWh+5lALjOsIN+5Ky4EcSrgUpROKQA1faQG0Wh5bIF5D38bA+0pR3+fXynkaUbqwCw==@kvack.org X-Gm-Message-State: AOJu0YzaO+s5a9drFvVEqqpUN2IvY7JxRx0wPRjiH52hS4NF86IKR1+I CjjOOOzK+gufI3kmPDciMJgakNIyox6+IQX2nAYhQZSGurhYp1W4o9uvS28p4sU= X-Google-Smtp-Source: AGHT+IH0PykjARYOlhRdYD8Ei00ntSXkZvlp+w/DvL/wK29HFMzX/PK1qWz6iq3HMQhndU3PBLr5iA== X-Received: by 2002:a05:622a:51:b0:458:3e20:65d3 with SMTP id d75a77b69052e-45b5e06627amr81705351cf.60.1727333299714; Wed, 25 Sep 2024 23:48:19 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([203.208.167.150]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-45b5257ff1esm23024611cf.38.2024.09.25.23.48.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Sep 2024 23:48:19 -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 v5 12/13] mm: multi-gen LRU: walk_pte_range() use pte_offset_map_rw_nolock() Date: Thu, 26 Sep 2024 14:46:25 +0800 Message-Id: <7e9c194a5efacc9609cfd31abb9c7df88b53b530.1727332572.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-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: 8AA224000D X-Stat-Signature: 4cu1fkjumaepo6j5hpk7gwhojkm6d44f X-HE-Tag: 1727333300-333487 X-HE-Meta: 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 k38ovmrM R8qyXP6jT0BLd6Z3wWT0zAweC6JnxjES2CB2+dDH2b7SGQA6qJqyn8B9+Zwy2brxDS2KXa46WgmAPuNCGHZMyCoSO3onSiSftvIDzp8CGZ8Rtvg0ao0e1RBOnpO9h3/kOtb7AiN54FbpeiP1F7JYBDs96n9QiHdPJGg0jBmb3+selxH4+Fbn9piNSPG2LvIO5oWwsoNZDpGfF2KRgLDuAKWQnpBhI7QosgXihP3ilVpYpHQ6bZQOyMc83EgLnOAyqBj99LqokyWxn+xdxSavBZJB7LywdhTyQUyewpRFKqtoO53WC/v8tA3z99HE2UENa3WGZpYCrAA2uyQXcljrotgf2xgKo3uJG17qzEO4TN5KvRyV3hJJfb9covBTeItJf259wiAQkxW8UyhNsWEo9WrQgnVPPhwL3VX7m9jVU89V4pndoQo6VuZzK5fjnNXAFC54pzOj9AIQnHzA= 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 walk_pte_range(), we may modify the pte entry after holding the ptl, so convert it to using pte_offset_map_rw_nolock(). At this time, 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 Reviewed-by: Muchun Song Acked-by: David Hildenbrand --- mm/vmscan.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 749cdc110c745..bdca94e663bc5 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3375,8 +3375,10 @@ 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_rw_nolock(args->mm, pmd, start & PMD_MASK, &pmdval, + &ptl); if (!pte) return false; if (!spin_trylock(ptl)) { @@ -3384,6 +3386,11 @@ 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) {