From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 82536CCD1AB for ; Wed, 22 Oct 2025 18:40:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DBB048E001F; Wed, 22 Oct 2025 14:40:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D6AF58E0010; Wed, 22 Oct 2025 14:40:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C32E28E001F; Wed, 22 Oct 2025 14:40:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id AF8648E0010 for ; Wed, 22 Oct 2025 14:40:42 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 6A6E7C0912 for ; Wed, 22 Oct 2025 18:40:42 +0000 (UTC) X-FDA: 84026616324.13.ED03212 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf28.hostedemail.com (Postfix) with ESMTP id 7DE87C0006 for ; Wed, 22 Oct 2025 18:40:40 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=C3SqrYvR; spf=pass (imf28.hostedemail.com: domain of npache@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=npache@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1761158440; a=rsa-sha256; cv=none; b=ctGR2wiLcp4Qu/ZluziomUMQAq4XXcaBDwho1LmiBtCondeA3O/93GE0tW2nPYF0bVZmdH TGmkmkRHNQEleCiCfkI/YEsgkgE2d+HlPE54Lp9RBEsdTm3kGwnAAd6iTmsaJkcst4PR1i edCKCHVniMYUqTh9w79fSEZpx6KuG9M= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=C3SqrYvR; spf=pass (imf28.hostedemail.com: domain of npache@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=npache@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1761158440; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=+jXNuiQ5bHnX5LcOt47Wp1opTjuPzrwwutPcN/KCqFQ=; b=tEbDVT/+AYjoFOeGtei6F+oTH5bAEfMSuKV7A2YXotQuOBwmpRd+uUNS5ktggKpR2Vw2Hh eme/Q6Ce6cKN6RlDYOC8iG//gejAHMEHVLSyLuAXbC01OE91ZmAyyzOIGBM0zquzzDtP4y KhdAowvZrgaz36jcLJ/ZfAElX28MPJc= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1761158439; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+jXNuiQ5bHnX5LcOt47Wp1opTjuPzrwwutPcN/KCqFQ=; b=C3SqrYvRtl2QnLR/+4sldXQD5rg1eMXwA0zXWz1OtjfUBewMlP2bY4hAWaibu/0Kav1Zk+ hoDLJBenB5a8HlOj+Bfh2TjCFqlONdXmTPHxFGNrLIayO04QbA2453PSsSxxyUmvVkFUyr nGIlqw3MRcdcVOQOobZS93VyI9QxudU= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-668-IY3uYX_EMg2HzlP-YAxfIw-1; Wed, 22 Oct 2025 14:40:35 -0400 X-MC-Unique: IY3uYX_EMg2HzlP-YAxfIw-1 X-Mimecast-MFC-AGG-ID: IY3uYX_EMg2HzlP-YAxfIw_1761158430 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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A54B819560A7; Wed, 22 Oct 2025 18:40:30 +0000 (UTC) Received: from h1.redhat.com (unknown [10.22.64.41]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 79C9F19560B4; Wed, 22 Oct 2025 18:40:21 +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 v12 mm-new 13/15] khugepaged: avoid unnecessary mTHP collapse attempts Date: Wed, 22 Oct 2025 12:37:15 -0600 Message-ID: <20251022183717.70829-14-npache@redhat.com> In-Reply-To: <20251022183717.70829-1-npache@redhat.com> References: <20251022183717.70829-1-npache@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Rspam-User: X-Stat-Signature: wrn63ig7yd5mxyr6hkzbdac3d5wcw5us X-Rspamd-Queue-Id: 7DE87C0006 X-Rspamd-Server: rspam09 X-HE-Tag: 1761158440-251344 X-HE-Meta: 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 0v4iD8M7 GaqxZN4ZAkfJALgz0+r93UHxY9xzD8U3BEcSzF8jqj1kDTSJl9Sh7x78LK2MYDHkqXuzOwZjB47P6RFzTOuiYbUSNf1PQ0apIMgHqcngJ8ymswMeStsB0vQvLQelyE6sSby/2gqLt6UBeMY7nsOio/AvaxzYmlHx5eq3StsWQAvf4vpenYRVf3Y4SzkCE1Qq4nH9+XwpC+G/hFiSuPjPmJDipdCQbD2/tkAGTxPFxozisUZDCfhmM6AeY7s/Y2iNsYdrVOyubVthN6NmsIPlaGkL/EPKqZbvSytpDE4/4hn753+xhlnKRdO2HoHyopBR7KTKlZJn4Kug4FEgr71aDY1vrVLRow6E+f1DyqImUHCvobRkQupmgl4ObLHqxafSu7v4mwF+EL5YErFsRuwbnfAIXTA== 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 e2319bfd0065..54f5c7888e46 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1431,10 +1431,39 @@ 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); - 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 += 1UL << order; + 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; + /* All other cases should stop collapse attempts */ + default: + break; } + break; } next_order: -- 2.51.0