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Mon, 01 Dec 2025 12:49:50 -0500 X-MC-Unique: 17XU2vohN7OLwRxYhfKiNg-1 X-Mimecast-MFC-AGG-ID: 17XU2vohN7OLwRxYhfKiNg_1764611385 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id AFE881955F2A; Mon, 1 Dec 2025 17:49:45 +0000 (UTC) Received: from h1.redhat.com (unknown [10.22.66.60]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 06CED1800361; Mon, 1 Dec 2025 17:49:35 +0000 (UTC) From: Nico Pache To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org Cc: david@redhat.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, dev.jain@arm.com, corbet@lwn.net, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, akpm@linux-foundation.org, baohua@kernel.org, willy@infradead.org, peterx@redhat.com, wangkefeng.wang@huawei.com, usamaarif642@gmail.com, sunnanyong@huawei.com, vishal.moola@gmail.com, thomas.hellstrom@linux.intel.com, yang@os.amperecomputing.com, kas@kernel.org, aarcange@redhat.com, raquini@redhat.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, tiwai@suse.de, will@kernel.org, dave.hansen@linux.intel.com, jack@suse.cz, cl@gentwo.org, jglisse@google.com, surenb@google.com, zokeefe@google.com, hannes@cmpxchg.org, rientjes@google.com, mhocko@suse.com, rdunlap@infradead.org, hughd@google.com, richard.weiyang@gmail.com, lance.yang@linux.dev, vbabka@suse.cz, rppt@kernel.org, jannh@google.com, pfalcato@suse.de Subject: [PATCH v13 mm-new 14/16] khugepaged: avoid unnecessary mTHP collapse attempts Date: Mon, 1 Dec 2025 10:46:25 -0700 Message-ID: <20251201174627.23295-15-npache@redhat.com> In-Reply-To: <20251201174627.23295-1-npache@redhat.com> References: <20251201174627.23295-1-npache@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Rspam-User: X-Rspamd-Queue-Id: 7D49C100012 X-Rspamd-Server: rspam11 X-Stat-Signature: cibx3k6dothbgguoqbrf8dthtyz8npbo X-HE-Tag: 1764611398-84520 X-HE-Meta: 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 rj0QgiCg VRByxtkDEvJVlMF6mGtQFA94OLeXtwB0GJoZt90Ysqql2JGptKpwEqCv2GRoCGl4DKR+5nxyJUXqWwa5O20i28CNFjwfW1QwaFoL30Z/aDTkiqsIzNB9wZiU1gK/CeLXZMlb4 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: There are cases where, if an attempted collapse fails, all subsequent orders are guaranteed to also fail. Avoid these collapse attempts by bailing out early. Signed-off-by: Nico Pache --- mm/khugepaged.c | 35 ++++++++++++++++++++++++++++++++++- 1 file changed, 34 insertions(+), 1 deletion(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index fcb927cd5456..daf39aab7e86 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1503,9 +1503,42 @@ static int mthp_collapse(struct mm_struct *mm, unsigned long address, ret = collapse_huge_page(mm, collapse_address, referenced, unmapped, cc, mmap_locked, order); - if (ret == SCAN_SUCCEED) { + + switch (ret) { + /* Cases were we continue to next collapse candidate */ + case SCAN_SUCCEED: collapsed += nr_pte_entries; + fallthrough; + case SCAN_PTE_MAPPED_HUGEPAGE: continue; + /* Cases were lower orders might still succeed */ + case SCAN_LACK_REFERENCED_PAGE: + case SCAN_EXCEED_NONE_PTE: + case SCAN_EXCEED_SWAP_PTE: + case SCAN_EXCEED_SHARED_PTE: + case SCAN_PAGE_LOCK: + case SCAN_PAGE_COUNT: + case SCAN_PAGE_LRU: + case SCAN_PAGE_NULL: + case SCAN_DEL_PAGE_LRU: + case SCAN_PTE_NON_PRESENT: + case SCAN_PTE_UFFD_WP: + case SCAN_ALLOC_HUGE_PAGE_FAIL: + goto next_order; + /* Cases were no further collapse is possible */ + case SCAN_CGROUP_CHARGE_FAIL: + case SCAN_COPY_MC: + case SCAN_ADDRESS_RANGE: + case SCAN_NO_PTE_TABLE: + case SCAN_ANY_PROCESS: + case SCAN_VMA_NULL: + case SCAN_VMA_CHECK: + case SCAN_SCAN_ABORT: + case SCAN_PAGE_ANON: + case SCAN_PMD_MAPPED: + case SCAN_FAIL: + default: + return collapsed; } } -- 2.51.1