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 53D2A2931D0 for ; Fri, 24 Jul 2026 01:34:54 +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=1784856895; cv=none; b=b/dHcj3PJDMsEK1o59S7MJF0kFt+vKZS5ZZxVftRWCskBY8N6Grs8gZw118O2/jVBoy1y2HsTgUAr7Xjxw6WKqLo9PN4krL61ywnNOTAdL5V2G1InG55akXWfTATn6z++1zM7y45q5C7LXXR/5Y5vfuwqBYaXmh4EwqwxA3TFqA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784856895; c=relaxed/simple; bh=ju+lLzyGsEqeWJRMLjDiPzMlELuc9NAHsGelr0wNqjk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bZUEuB3nYYuPZiVRCAppAe7dVCFuJMg6Go2JarBEesdpZvPjUHSdMnNaZHnyS3oVivdiKInZ+0i2EvzrIuLF3IyPMv/GuiP3SWvefdb4f9oDrjhVjSgME0IfRD+XWje6dQKBX9DM0iEVT9g06BeejUVPYOW/+he5L0MYLxoq6Vo= 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=StJ14ih3; 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="StJ14ih3" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1784856893; 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=aIh7RPBAnJJFoaMlpLHLjWKSHstbWhClnoICZysb4Os=; b=StJ14ih3BUTj/FBRnZahmlA5xZ/MPNaEwDKcMiPTaVg/ktkhlCf61oKzB9fsEH2tp7p/Rz T2Q68E8jK6ORsquMM3LD8qB3olGXKE0ZcGBDwkQNYzoo52A2zPN5L1jrMoT7Sb1ei6ZfDe NSIhHi4Nzhf1kTkPeZR5tp3zcb0q03Q= Received: from mx-prod-mc-03.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-154-u5j-uJGsMHWUyqn-nW9p0A-1; Thu, 23 Jul 2026 21:34:49 -0400 X-MC-Unique: u5j-uJGsMHWUyqn-nW9p0A-1 X-Mimecast-MFC-AGG-ID: u5j-uJGsMHWUyqn-nW9p0A_1784856886 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D9A1D1944CFD; Fri, 24 Jul 2026 01:34:45 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.22.80.238]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 1B5EE180059C; Fri, 24 Jul 2026 01:34:40 +0000 (UTC) From: Luiz Capitulino To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, david@kernel.org, baolin.wang@linux.alibaba.com, ziy@nvidia.com, lance.yang@linux.dev Cc: corbet@lwn.net, tsbogend@alpha.franken.de, maddy@linux.ibm.com, mpe@ellerman.id.au, agordeev@linux.ibm.com, gerald.schaefer@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, x86@kernel.org, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, ira.weiny@intel.com, hughd@google.com, dave.hansen@linux.intel.com, djbw@kernel.org, vishal.l.verma@intel.com, dave.jiang@intel.com, akpm@linux-foundation.org, yintirui@huawei.com, ljs@kernel.org, dev.jain@arm.com Subject: [PATCH v6 02/14] mm: shmem: shmem_getattr(): set blksize to highest supported THP order Date: Thu, 23 Jul 2026 21:34:06 -0400 Message-ID: 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-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Today, shmem_getattr() sets stat->blksize to PMD size whenever shmem_huge_global_enabled() returns non-zero. While this works fine for the normal THP-enabled case as explained by Baolin in [1], this has two problems: 1. Theoretically, when shmem is configured for within_size, this could set blksize to PMD size even though the allocation may be a smaller mTHP order 2. A future commit will allow shmem THP support to be enabled even when the CPU doesn't support PMD-sized pages. We should not allow blksize to be set to PMD size in this case In order to fix #1 and prepare for #2, this commit sets blksize to the size of the highest supported order returned by shmem_huge_global_enabled(). [1] https://lore.kernel.org/linux-mm/6591a74c-7ef9-4614-9ae9-cb2fbed86ebf@linux.alibaba.com/ Suggested-by: Baolin Wang Acked-by: Zi Yan Signed-off-by: Luiz Capitulino --- mm/shmem.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index 5071177059a9..19534e21b61f 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1287,6 +1287,7 @@ static int shmem_getattr(struct mnt_idmap *idmap, { struct inode *inode = path->dentry->d_inode; struct shmem_inode_info *info = SHMEM_I(inode); + unsigned int orders; /* Fast-path hint; recalc under info->lock corrects any stale read. */ if (data_race(info->alloced - info->swapped != inode->i_mapping->nrpages)) @@ -1303,8 +1304,9 @@ static int shmem_getattr(struct mnt_idmap *idmap, STATX_ATTR_NODUMP); generic_fillattr(idmap, request_mask, inode, stat); - if (shmem_huge_global_enabled(inode, 0, 0, false, NULL, 0)) - stat->blksize = HPAGE_PMD_SIZE; + orders = shmem_huge_global_enabled(inode, 0, 0, false, NULL, 0); + if (orders) + stat->blksize = PAGE_SIZE << highest_order(orders); if (request_mask & STATX_BTIME) { stat->result_mask |= STATX_BTIME; -- 2.55.0