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Fri, 06 Dec 2024 02:46:30 -0800 (PST) Received: from localhost ([196.207.164.177]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-434da0d26a3sm54046975e9.1.2024.12.06.02.46.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Dec 2024 02:46:30 -0800 (PST) Date: Fri, 6 Dec 2024 13:46:27 +0300 From: Dan Carpenter To: Qi Zheng Cc: linux-mm@kvack.org Subject: [bug report] mm: pgtable: reclaim empty PTE page in madvise(MADV_DONTNEED) Message-ID: <224e6a4e-43b5-4080-bdd8-b0a6fb2f0853@stanley.mountain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Queue-Id: 1421818000F X-Stat-Signature: rrjyqkdyw55r7pcxzc97f87j87dxxduy X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1733481989-384550 X-HE-Meta: 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 YvL9kPoy 8oF7OqsiFFPN7bpwptuzpYO1/BLlKUmajtJKRY4YorFhn4L1wFXZoUx0Zwn0HCqsMx30e1xQKt4/3/k+ExCj0vpnbqpf5XOZBzBd73JnkdRhyQ6+nqCgZMy/F679lVykerYEL5J2zjMA//WihT0oh7FBuWKomh+C3a90Lw2BvJH4X/WfzyAP38fHo3ubJmhGJC6ndJp1UIQfJvcnq8NR5C+mbOQRjdqAj5E9CL1j4+qa13ewRszjEqoBcQ1gbRlds2HeP+wdYrPl5JrUSowLq7WOqfbUd2LOFuUUo05TrDyem7O4zSzo6PtaaIg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000005, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hello Qi Zheng, Commit e3aafd2d3551 ("mm: pgtable: reclaim empty PTE page in madvise(MADV_DONTNEED)") from Dec 4, 2024 (linux-next), leads to the following Smatch static checker warning: mm/pt_reclaim.c:69 try_to_free_pte() error: uninitialized symbol 'ptl'. mm/pt_reclaim.c 35 void try_to_free_pte(struct mm_struct *mm, pmd_t *pmd, unsigned long addr, 36 struct mmu_gather *tlb) 37 { 38 pmd_t pmdval; 39 spinlock_t *pml, *ptl; 40 pte_t *start_pte, *pte; 41 int i; 42 43 pml = pmd_lock(mm, pmd); 44 start_pte = pte_offset_map_rw_nolock(mm, pmd, addr, &pmdval, &ptl); 45 if (!start_pte) 46 goto out_ptl; ptl is uninitialized on error. 47 if (ptl != pml) 48 spin_lock_nested(ptl, SINGLE_DEPTH_NESTING); 49 50 /* Check if it is empty PTE page */ 51 for (i = 0, pte = start_pte; i < PTRS_PER_PTE; i++, pte++) { 52 if (!pte_none(ptep_get(pte))) 53 goto out_ptl; 54 } 55 pte_unmap(start_pte); 56 57 pmd_clear(pmd); 58 59 if (ptl != pml) 60 spin_unlock(ptl); 61 spin_unlock(pml); 62 63 free_pte(mm, addr, tlb, pmdval); 64 65 return; 66 out_ptl: 67 if (start_pte) 68 pte_unmap_unlock(start_pte, ptl); --> 69 if (ptl != pml) ^^^ Uninitialized variable 70 spin_unlock(pml); 71 } regards, dan carpenter