From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 4EF0041930D; Thu, 11 Jun 2026 16:09:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781194188; cv=none; b=Ir3SnhZzcK+iLKdKS++HfTQq2njq+N2vc4DqSdK2gVvMclyqOtxvyI6lEZAXu6RKObj94+DLil1UFU1cwSuJbitLMzu8yma6G87G3W2dLzcPWp8hQ6uO/U7BoX1rwcSl/Jx5tzY3uCxmdkO5mn7IEKcFDLC9gxn13PdKk6ppaCQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781194188; c=relaxed/simple; bh=X4Jpc+wpAAwsnek0hOUnQEIdn0MKFirDP7V0B2MS2ho=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=vAxQJn3gmTEM8HO4lF275mSWS2NOHwQU+0QQdtmu0ZjzX0XqlTQj10Z1uaSVEENgUDTmg88x4oAqN4B3eiusU3rAvlUg7UqmCB5/Z/o/aob4ftH5Yr3LOVB2fDviNGoH7KSCOnqmZK5jcmx+1MCxBoZ52qRzg7aYKjRikJZ8QkM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fgcmbJ0M; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fgcmbJ0M" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 846571F00893; Thu, 11 Jun 2026 16:09:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781194186; bh=YjaHrluNbQcW3RW6hKc6GUqxEBJ52tD5SdhNClOzEbQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=fgcmbJ0MetdVZUeVJ5A0HVyULJLaT6nRpg6uRYKgl+y/jCCS3ZgEwRFS5Y/faTQZX 0970T4XqaBsfe1KKzmeFLFAJhtd3sobbsAKgQUm1TALq/7qwQkhHWYUkbgZa6kAXFL Qyg7kPuR299i+5v0MI+apcqqpSOpCWMb7bdYdzD82tdZWz6qQSrNaicxedQD4HAyyx H0eeLfmNt/y9IQ1UXn6HoGzFKSvwyBYS7RpMSVXI3Fv71cTnwAXMRXjbYq6ttB42uC JxFC/iksGp81nWha0cQlVSNSSl6hCFnlb6aNpgkFKsZ+J3IWHWON3F/VJCPXbQxaO4 mqkGyRBzXShbQ== Message-ID: <7e7cbc60-e9c7-4a63-9d4b-4e8fcad7bfc0@kernel.org> Date: Thu, 11 Jun 2026 18:09:40 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [Bug Report] Elevated PMD nr_anon after running selftests To: Nico Pache , Linux MM , linux-kselftest@vger.kernel.org, LKML , linux-cxl@vger.kernel.org Cc: "Lorenzo Stoakes (Oracle)" , Oscar Salvador , Andrew Morton , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple References: From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/11/26 17:58, Nico Pache wrote: > Hi, > > While testing my mTHP code I noticed that mm selftests caused an accounting error in > /sys/kernel/mm/transparent_hugepage/hugepages-2048kB/stats/nr_anon > > At first I thought I might have caused a regression, but when retesting with 7.1-rc5 (without my code), the issue was still present. > > This issue occurs in two mm selftests: > 1) hmm test > 2) migration - private_anon_htlb test > > I spoke to David about this and he suggested the following diff which seems to have solved both issues. > > David would you like to send a formal patch or patches? > > Cheers, > -- Nico > > Diff for (1) > > diff --git a/mm/memremap.c b/mm/memremap.c > index 053842d45cb1..683a77dd679d 100644 > --- a/mm/memremap.c > +++ b/mm/memremap.c > @@ -425,6 +425,7 @@ void free_zone_device_folio(struct folio *folio) > mem_cgroup_uncharge(folio); > > if (folio_test_anon(folio)) { > + mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON, -1); > for (i = 0; i < nr; i++) > __ClearPageAnonExclusive(folio_page(folio, i)); > } Wasn't there another issue with hugetlb? diff --git a/mm/migrate.c b/mm/migrate.c index 8a64291ab5b4..0aec894266f2 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)) Yeah, if you have some capacity, please send patches (and figure out Fixes:) :) -- Cheers, David