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Fri, 19 Sep 2025 00:12:56 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b1fcfe88e79sm361800366b.55.2025.09.19.00.12.55 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Fri, 19 Sep 2025 00:12:56 -0700 (PDT) From: Wei Yang To: akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, xu.xin16@zte.com.cn Cc: linux-mm@kvack.org, Wei Yang , Kiryl Shutsemau Subject: [Patch v2 1/2] mm/ksm: get mm_slot by mm_slot_entry() when slot is !NULL Date: Fri, 19 Sep 2025 07:12:43 +0000 Message-Id: <20250919071244.17020-2-richard.weiyang@gmail.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20250919071244.17020-1-richard.weiyang@gmail.com> References: <20250919071244.17020-1-richard.weiyang@gmail.com> X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 6A1EC180002 X-Stat-Signature: dn7gnggycr7zospet8w9cqzi51ueemmb X-Rspam-User: X-HE-Tag: 1758265978-522152 X-HE-Meta: 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 I/wG+YHa 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 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: When using mm_slot in ksm, there is code snip like: slot = mm_slot_lookup(mm_slots_hash, mm); mm_slot = mm_slot_entry(slot, struct ksm_mm_slot, slot); if (mm_slot && ..) { } The mm_slot_entry() won't return a valid value if slot is NULL generally. But currently it works since slot is the first element of struct ksm_mm_slot. To reduce the ambiguity and make it robust, access mm_slot_entry() when slot is !NULL. Signed-off-by: Wei Yang Cc: Lance Yang Cc: David Hildenbrand Cc: Dev Jain Cc: Kiryl Shutsemau Cc: xu.xin16@zte.com.cn --- v2: * check on slot before continue --- mm/ksm.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/mm/ksm.c b/mm/ksm.c index 2ef29802a49b..6ff7f840e50a 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -2939,15 +2939,17 @@ void __ksm_exit(struct mm_struct *mm) spin_lock(&ksm_mmlist_lock); slot = mm_slot_lookup(mm_slots_hash, mm); - mm_slot = mm_slot_entry(slot, struct ksm_mm_slot, slot); - if (mm_slot && ksm_scan.mm_slot != mm_slot) { - if (!mm_slot->rmap_list) { - hash_del(&slot->hash); - list_del(&slot->mm_node); - easy_to_free = 1; - } else { - list_move(&slot->mm_node, - &ksm_scan.mm_slot->slot.mm_node); + if (slot) { + mm_slot = mm_slot_entry(slot, struct ksm_mm_slot, slot); + if (ksm_scan.mm_slot != mm_slot) { + if (!mm_slot->rmap_list) { + hash_del(&slot->hash); + list_del(&slot->mm_node); + easy_to_free = 1; + } else { + list_move(&slot->mm_node, + &ksm_scan.mm_slot->slot.mm_node); + } } } spin_unlock(&ksm_mmlist_lock); -- 2.34.1