From nobody Fri Dec 19 20:38:25 2025 Received: from out30-99.freemail.mail.aliyun.com (out30-99.freemail.mail.aliyun.com [115.124.30.99]) (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 670EA1C32 for ; Thu, 5 Jun 2025 08:01:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.99 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749110482; cv=none; b=ZeNp6NXvbAaQTJ+jZpSJxEo1Aj4Y0Jk/EUJfGwZ2fjKmxquMuA1i1u2x9NtXP08f9SsqepGjd8b+y59rfKyQEM2evgqaphUbotnEIpyTCnOmbo2HTVVUVdcA5fjEZAeXMbqxfTijBMRrKAreM2/63vS95UQjhxTfSs3pzWlEpqQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749110482; c=relaxed/simple; bh=r6E3rglfRLSqSLXHR+V3IXnb3kPvV51qptkCoiFWZdo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=OP/fQ1wM7AQwsXkh8n7VUkoVgolkFb80gwJCRggLHUEspNIxqyP9oUdLGfpQBTi3fhVWntvGTPzG8z0GkLsrv8qTn9vpoOQPbrmyutpjYaJq1CuhsEul7/8AWWJTrY9mVxk9ZB93rdH7NAXvYNj4vRLr2BupayFygPkzgz+m3xs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=f5A91PJC; arc=none smtp.client-ip=115.124.30.99 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="f5A91PJC" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1749110474; h=From:To:Subject:Date:Message-ID:MIME-Version:Content-Type; bh=jCGzSGCdqXE9W9t2gnUeBiPltG2v3zMxn7QoZ0xpXD4=; b=f5A91PJCmZzJLnNaTWPX6XjknLVdaE4FSLwdzMYaQ+xIU+PlTzNDo0cNrRZoN22/+Rr3w8yHhr2vA8hOtpLslrufCE9Xik5tUtbS4fmhHJx1sUc55PhKAPwOltuLPZcQ9XO/4DNcLIGstbbBEYJhfwUK0+RK/Tf0Z0+dsdhF9vo= Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Wd7WSL6_1749110473 cluster:ay36) by smtp.aliyun-inc.com; Thu, 05 Jun 2025 16:01:14 +0800 From: Baolin Wang To: akpm@linux-foundation.org, hughd@google.com, david@redhat.com Cc: lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/2] mm: huge_memory: disallow hugepages if the system-wide THP sysfs settings are disabled Date: Thu, 5 Jun 2025 16:00:58 +0800 Message-ID: <8eefb0809c598fadaa4a022634fba5689a4f3257.1749109709.git.baolin.wang@linux.alibaba.com> X-Mailer: git-send-email 2.43.5 In-Reply-To: References: 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: quoted-printable The MADV_COLLAPSE will ignore the system-wide Anon THP sysfs settings, which means that even though we have disabled the Anon THP configuration, MADV_CO= LLAPSE will still attempt to collapse into a Anon THP. This violates the rule we h= ave agreed upon: never means never. Another rule for madvise, referring to David's suggestion: =E2=80=9Callowin= g for collapsing in a VM without VM_HUGEPAGE in the "madvise" mode would be fine". To address this issue, should check whether the Anon THP configuration is d= isabled in thp_vma_allowable_orders(), even when the TVA_ENFORCE_SYSFS flag is set. In summary, the current strategy is: 1. If always & orders =3D=3D 0, and madvise & orders =3D=3D 0, and hugepage= _global_enabled() =3D=3D false (global THP settings are not enabled), it means mTHP of that orders are pro= hibited from being used, then madvise_collapse() is forbidden for that orders. 2. If always & orders =3D=3D 0, and madvise & orders =3D=3D 0, and hugepage= _global_enabled() =3D=3D true (global THP settings are enabled), and inherit & orders =3D=3D 0, it means = mTHP of that orders are still prohibited from being used, thus madvise_collapse() is not= allowed for that orders. Reviewed-by: Zi Yan Signed-off-by: Baolin Wang Reviewed-by: Dev Jain Tested-by: Nico Pache --- include/linux/huge_mm.h | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 2f190c90192d..199ddc9f04a1 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -287,20 +287,35 @@ unsigned long thp_vma_allowable_orders(struct vm_area= _struct *vma, unsigned long orders) { /* Optimization to check if required orders are enabled early. */ - if ((tva_flags & TVA_ENFORCE_SYSFS) && vma_is_anonymous(vma)) { - unsigned long mask =3D READ_ONCE(huge_anon_orders_always); + if (vma_is_anonymous(vma)) { + unsigned long always =3D READ_ONCE(huge_anon_orders_always); + unsigned long madvise =3D READ_ONCE(huge_anon_orders_madvise); + unsigned long inherit =3D READ_ONCE(huge_anon_orders_inherit); + unsigned long mask =3D always | madvise; + + /* + * If the system-wide THP/mTHP sysfs settings are disabled, + * then we should never allow hugepages. + */ + if (!(mask & orders) && !(hugepage_global_enabled() && (inherit & orders= ))) + return 0; + + if (!(tva_flags & TVA_ENFORCE_SYSFS)) + goto skip; =20 + mask =3D always; if (vm_flags & VM_HUGEPAGE) - mask |=3D READ_ONCE(huge_anon_orders_madvise); + mask |=3D madvise; if (hugepage_global_always() || ((vm_flags & VM_HUGEPAGE) && hugepage_global_enabled())) - mask |=3D READ_ONCE(huge_anon_orders_inherit); + mask |=3D inherit; =20 orders &=3D mask; if (!orders) return 0; } =20 +skip: return __thp_vma_allowable_orders(vma, vm_flags, tva_flags, orders); } =20 --=20 2.43.5