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Tue, 19 Aug 2025 09:45:31 -0400 X-MC-Unique: kyYq5qvsNpunGuM_q3lK-Q-1 X-Mimecast-MFC-AGG-ID: kyYq5qvsNpunGuM_q3lK-Q_1755611126 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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 8979F180034D; Tue, 19 Aug 2025 13:45:26 +0000 (UTC) Received: from h1.redhat.com (unknown [10.22.64.137]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3C00D19560BC; Tue, 19 Aug 2025 13:45:08 +0000 (UTC) From: Nico Pache To: linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@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, kirill.shutemov@linux.intel.com, 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 Subject: [PATCH v10 08/13] khugepaged: avoid unnecessary mTHP collapse attempts Date: Tue, 19 Aug 2025 07:42:00 -0600 Message-ID: <20250819134205.622806-9-npache@redhat.com> In-Reply-To: <20250819134205.622806-1-npache@redhat.com> References: <20250819134205.622806-1-npache@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 6EA7840002 X-Stat-Signature: 8qffd5z11mgdgc6981x5x3p8na8d58b3 X-Rspam-User: X-HE-Tag: 1755611136-328884 X-HE-Meta: U2FsdGVkX188IY1w6fVfOCMAH4fBM3aLDnycZAtpGo8m1AUy4pqOmxPtgbwJESu1Asjhy3nYnw9wRVqoqVFuPn9n9qUJ8N50RyvLg+1i2hgZm7xYUmhPznPCBCYl7dBp9xc47LmvUchJ6NIylvNdrCNvNdM9+iOTnC1SKrw2AqSVPFoURx3sAg+1t6cCeuxap0VVJMaK2zLhhvv/eMKCEtRIFIXnAxHITDIpbS2y2t70K7Kz44S/EQcJILzfzkM7ZeODBx5L9LvEA9ohA5Uv9GgytvpiC6ZO1X2c0DIGJSBAC8wb6AtkNyXcKgEcb3NhCRdUMsPeOe3bLLvU/6GwvVqZbzPYQys7SuodOB1ZpGFqQQgc5EmLTC5EEyHaGhAPeKopwOLqtOqxItlUde5TS7qZLg2rZOLDAdFV7dgSrD/aZbQc5OjvAcefJwbxqMM6VwA5Vq49d4mlti0lu4mVKzwmg0HMe+W/f7pAub709cfwaIki+kYf5fFhkkSRU8F4OixvnLsHY0d+Ygekj5JD6vLmsXd63HxJieJQJ38WUj5bkfIH5OB1fS/in/WWoj6mjecznfqoHySKptGOAF19HCLUQ27dKIlBicmwW3h9QUZNWNVX4iK5jU33krZjznIM06GhSdfLiquEJe9Lk6miIgIjD8DptRbeEneM5PJNZkRps0NvzydkYcxu5BCVxFyycZ+H0XQ7gW51Gfs1UQwcPyjlaScG2Vx+oS9Z671LwuDaiF4fOLijv5z2Svil2zg6caByUjrcBb//JyLZ+Ea9jde3BKEZ0Fy4EyqMYLoREiNXLou2bQ6oQCKLrOwhs8r3jSZU+2xgxcYxn7t47OfyryZxdMI1LUzDqKm2vWRq1bvBmDM+kmaPdf6/rGKVUh7TBzmyrS+1W8bST7jVyyg7+ZMH4LR5qSft2XgWAHC9t8RZjs2xaeI+i93bslNsoTVgm4jjA7B35+ekicH9F+R u01bQYBo fIuHl8xYK70o4KzFIjzn3oMdzlouulCLoJLJMr2dMu8thFd0xzxb06GOk1S8Hbpl+qhkFJbxL5oAYlyLgLXHl2nEn3tsfNwFeNeKlA+fdMqoURtaWZRlPNDdSlw/V15MI5eRk97Tr3O13AS9CjrDIWOBlZVlB6hfT812grrFLmC4SbJ02qxsZ2Ka6LLnYt64ENGmy7J9+/LUJv4FFM+O+MUAexw0ywka04DMSvcWgQ2I5Uq4PdLJ9zCsmIvRqGZtLjxJFX5gBa9bxx8N+PC9VH+ZxU0YQj2Hqv4e2/vkIYFITpRzosC61hH8TuONgTyA48EbNnawYOloxqrgNTLfSrGWRiAn6s+AxPGeALCA5rSs0IZZ/q9Dw9hK/hi88pQD3gIOFj5i5reM06+tJQ7sokHLKDg== 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 | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 6a4cf7e4a7cc..7d9b5100bea1 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1389,10 +1389,39 @@ static int collapse_scan_bitmap(struct mm_struct *mm, unsigned long address, ret = collapse_huge_page(mm, address, referenced, unmapped, cc, mmap_locked, order, offset * KHUGEPAGED_MIN_MTHP_NR); - if (ret == SCAN_SUCCEED) { + + /* + * Analyze failure reason to determine next action: + * - goto next_order: try smaller orders in same region + * - continue: try other regions at same order + * - break: stop all attempts (system-wide failure) + */ + switch (ret) { + /* Cases were we should continue to the next region */ + case SCAN_SUCCEED: collapsed += (1 << order); + case SCAN_PAGE_RO: + 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; + /* All other cases should stop collapse attempts */ + default: + break; } + break; } next_order: -- 2.50.1