From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 112703191CE for ; Thu, 2 Jul 2026 17:25:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783013130; cv=none; b=pRqJeezpQGSUbhCLtTi/3fyVCmmLspeKX3wrYXwlf5s3USpAiiJgfpr8mH9x5d53nlRmt3UsvJGZVjf9HBYia5uiE1vqQJyfjl19/uFnFPCxyvyS2GTl7a+CQchEn/DOsyjhlwasNFrO4HkHUEmnuGlg2DVnA8cLyRrkcV01UVM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783013130; c=relaxed/simple; bh=yboSpJ802K0S2cDoLeg+lmU6Mj9OqOoWR8jTcxxEsi0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=atX9fr0TT4zg29sspEMW6VfAAXhbGpWbJXZ2BeRBbcPUj4ArG4KA0tTvNr4VSph4xvsTZZpYM9vDoo6bfZRZ6kXyROKtY1Pg7pkGLk4p3V8M9S8BW65HaF0a+LobuE9i0okf5nKGqTksMQS0gME8l0BAW4aYRkeHtU0YJik9XWU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=JT/KkjPI; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="JT/KkjPI" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1783013128; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=cBefviiafkFbe/nsc/cyLo5CV934Kk6BkNirD8bq4mc=; b=JT/KkjPIlbroq5pf5LRyfYXwKp1BWiW2eVA6PY4uphi5DTMKe2Vz0V1F5Pxt2RvVk9N+hT l3BdP2LYy68XPOC36lEXpITDhcbgGAMSSwSCi0wa/EC9us6dV+NDJttEnkJOrfXYUHvYRn 04AUNKXPXNvaME2P4KfTnCvV3KZ3/dA= 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-8-YlzfNNoRPHuWMl6LqaNVfA-1; Thu, 02 Jul 2026 13:25:22 -0400 X-MC-Unique: YlzfNNoRPHuWMl6LqaNVfA-1 X-Mimecast-MFC-AGG-ID: YlzfNNoRPHuWMl6LqaNVfA_1783013120 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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 950071944CF2; Thu, 2 Jul 2026 17:25:19 +0000 (UTC) Received: from p1.redhat.com (unknown [10.22.76.7]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 4486E30030D0; Thu, 2 Jul 2026 17:25:10 +0000 (UTC) From: Nico Pache To: Barry Song , David Hildenbrand , linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: ljs@kernel.org, willy@infradead.org, Nico Pache , Oscar Salvador , Andrew Morton , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple Subject: [PATCH 2/2] mm/migrate: exclude hugetlb folios from MTHP_STAT_NR_ANON accounting Date: Thu, 2 Jul 2026 11:25:47 -0600 Message-ID: <20260702172548.37075-3-npache@redhat.com> In-Reply-To: <20260702172548.37075-1-npache@redhat.com> References: <20260702172548.37075-1-npache@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 __folio_migrate_mapping() increments MTHP_STAT_NR_ANON for the destination folio when `folio_test_anon(folio) && folio_test_large(folio)` is true. However, hugetlb folios satisfy both conditions despite having a completely separate accounting system; they use hugetlb_add_anon_rmap() which does not touch mTHP stats, and their free path also bypasses the mTHP decrement in __free_pages_prepare(). This causes MTHP_STAT_NR_ANON to be incremented on each hugetlb migration without a corresponding decrement, permanently inflating the nr_anon counter. Add a !folio_test_hugetlb() check to both places in __folio_migrate_mapping() so that only actual mTHP folios are counted. Fixes: 5d65c8d758f2 ("mm: count the number of anonymous THPs per size") Co-developed-by: David Hildenbrand Signed-off-by: David Hildenbrand Signed-off-by: Nico Pache --- mm/migrate.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index d9b23909d716..9fd50ea25d2d 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -590,7 +590,8 @@ static int __folio_migrate_mapping(struct address_space *mapping, /* No turning back from here */ newfolio->index = folio->index; newfolio->mapping = folio->mapping; - if (folio_test_anon(folio) && folio_test_large(folio)) + if (folio_test_anon(folio) && folio_test_large(folio) && + !folio_test_hugetlb(folio)) mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON, 1); if (folio_test_swapbacked(folio)) __folio_set_swapbacked(newfolio); @@ -623,7 +624,8 @@ static int __folio_migrate_mapping(struct address_space *mapping, */ newfolio->index = folio->index; newfolio->mapping = folio->mapping; - if (folio_test_anon(folio) && folio_test_large(folio)) + if (folio_test_anon(folio) && folio_test_large(folio) && + !folio_test_hugetlb(folio)) mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON, 1); folio_ref_add(newfolio, nr); /* add cache reference */ if (folio_test_swapbacked(folio)) -- 2.54.0