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Fri, 05 Jun 2026 12:17:31 -0400 X-MC-Unique: LIpes0QPPVuIxpV-J_iW3A-1 X-Mimecast-MFC-AGG-ID: LIpes0QPPVuIxpV-J_iW3A_1780676250 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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id F21B9180061E; Fri, 5 Jun 2026 16:17:29 +0000 (UTC) Received: from p1.redhat.com (unknown [10.44.22.9]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 36F2D1800351; Fri, 5 Jun 2026 16:17:11 +0000 (UTC) From: Nico Pache To: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Cc: aarcange@redhat.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, byungchul@sk.com, catalin.marinas@arm.com, cl@gentwo.org, corbet@lwn.net, dave.hansen@linux.intel.com, david@kernel.org, dev.jain@arm.com, gourry@gourry.net, hannes@cmpxchg.org, hughd@google.com, jack@suse.cz, jackmanb@google.com, jannh@google.com, jglisse@google.com, joshua.hahnjy@gmail.com, kas@kernel.org, lance.yang@linux.dev, liam@infradead.org, ljs@kernel.org, mathieu.desnoyers@efficios.com, matthew.brost@intel.com, mhiramat@kernel.org, mhocko@suse.com, npache@redhat.com, peterx@redhat.com, pfalcato@suse.de, rakie.kim@sk.com, raquini@redhat.com, rdunlap@infradead.org, richard.weiyang@gmail.com, rientjes@google.com, rostedt@goodmis.org, rppt@kernel.org, ryan.roberts@arm.com, shivankg@amd.com, sunnanyong@huawei.com, surenb@google.com, thomas.hellstrom@linux.intel.com, tiwai@suse.de, usamaarif642@gmail.com, vbabka@suse.cz, vishal.moola@gmail.com, wangkefeng.wang@huawei.com, will@kernel.org, willy@infradead.org, yang@os.amperecomputing.com, ying.huang@linux.alibaba.com, ziy@nvidia.com, zokeefe@google.com, Usama Arif Subject: [PATCH mm-unstable v19 12/14] mm/khugepaged: avoid unnecessary mTHP collapse attempts Date: Fri, 5 Jun 2026 10:14:19 -0600 Message-ID: <20260605161422.213817-13-npache@redhat.com> In-Reply-To: <20260605161422.213817-1-npache@redhat.com> References: <20260605161422.213817-1-npache@redhat.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-MFC-PROC-ID: whixvu6jDmMQR5M2rBQopGr9R77Dyde64ymRz3ovl08_1780676250 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true 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. Reviewed-by: Lorenzo Stoakes Acked-by: Usama Arif Acked-by: David Hildenbrand (Arm) Signed-off-by: Nico Pache --- mm/khugepaged.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 430047316f43..7de92b28dd30 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1499,6 +1499,7 @@ static enum scan_result mthp_collapse(struct mm_struct *mm, collapse_address = address + offset * PAGE_SIZE; ret = collapse_huge_page(mm, collapse_address, referenced, unmapped, cc, order); + switch (ret) { /* Cases where we continue to next collapse candidate */ case SCAN_SUCCEED: @@ -1509,6 +1510,18 @@ static enum scan_result mthp_collapse(struct mm_struct *mm, /* Cases where lower orders might still succeed */ case SCAN_ALLOC_HUGE_PAGE_FAIL: alloc_failed = true; + fallthrough; + 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_NULL: + case SCAN_DEL_PAGE_LRU: + case SCAN_PTE_NON_PRESENT: + case SCAN_PTE_UFFD_WP: + case SCAN_PAGE_LAZYFREE: last_result = ret; goto next_order; /* Cases where no further collapse is possible */ -- 2.54.0