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 8B619F459F7 for ; Fri, 10 Apr 2026 16:00:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B27F86B009B; Fri, 10 Apr 2026 12:00:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AD8F36B009E; Fri, 10 Apr 2026 12:00:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9EEC26B009F; Fri, 10 Apr 2026 12:00:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 91B356B009B for ; Fri, 10 Apr 2026 12:00:05 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 3F03CB9C2D for ; Fri, 10 Apr 2026 16:00:05 +0000 (UTC) X-FDA: 84643107570.24.E1B2029 Received: from out-172.mta0.migadu.com (out-172.mta0.migadu.com [91.218.175.172]) by imf28.hostedemail.com (Postfix) with ESMTP id 398F8C0011 for ; Fri, 10 Apr 2026 16:00:02 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=lZkU3a2r; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf28.hostedemail.com: domain of lance.yang@linux.dev designates 91.218.175.172 as permitted sender) smtp.mailfrom=lance.yang@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1775836803; a=rsa-sha256; cv=none; b=pZtM7/rApRXY5Mu7Bpjo9kzMCzIVUa2SuPHl6lUL/FuAkFUaZM9kOfCWfiRLrwdwX/aZNX cLY/uBDG6caMtr8f9mGhWm731P3NNUC41ukX0G4LyIvBIJZpYh+ZdO05AlN+9OUarAHS1r 1T469SbC7sBaBfcevXkSkS93z9wQc9s= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=lZkU3a2r; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf28.hostedemail.com: domain of lance.yang@linux.dev designates 91.218.175.172 as permitted sender) smtp.mailfrom=lance.yang@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1775836803; 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-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Fp69nvi8vfzePQ4r72WtQoyz3vGVsf9eWxbGaVqWFg8=; b=QeQ8R4Q2Z94pcN7Lk+W6/vPnITJ7NkxLekZAGUKjsKEXOSolrGWQIpXM+h2j2Q1WaiMco9 4KqGszwO8bMCZV7OPXX6AxTIqIqkyD0CZGGAyreZj0sgWB7/wGhzjnaj0Zc8uWAf3tXLqK zyKN6j+vfVO6C50hqHuDY1Cb5JBveSw= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1775836800; 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=Fp69nvi8vfzePQ4r72WtQoyz3vGVsf9eWxbGaVqWFg8=; b=lZkU3a2r1eBilnZoCEuBaVnKpRHbeu4XB1hX/wQNN0o6A4IkvYn0CdSgIXL8mvywcuamhI 6Rbl7q36L8b7BREjPmzIk6CWxfiXVXMBV7zYTj0rytk1ezzNfgD130Dayp49686v1a7laI lR75D1TZtW8RtqJP+c8wqS8IamWlH9M= From: Lance Yang To: luizcap@redhat.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, david@kernel.org, baolin.wang@linux.alibaba.com, ryan.roberts@arm.com, akpm@linux-foundation.org, ljs@kernel.org, ziy@nvidia.com, Liam.Howlett@oracle.com, npache@redhat.com, dev.jain@arm.com, baohua@kernel.org, Lance Yang Subject: Re: [PATCH v3 06/10] mm: shmem: drop has_transparent_hugepage() usage Date: Fri, 10 Apr 2026 23:59:49 +0800 Message-Id: <20260410155949.61736-1-lance.yang@linux.dev> In-Reply-To: <020a4fe05e8ac52ca47c27b0fbb6a07c163a118f.1775679721.git.luizcap@redhat.com> References: <020a4fe05e8ac52ca47c27b0fbb6a07c163a118f.1775679721.git.luizcap@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: rqjtxmfcc3yhwzie33rpdgt1jbozmwro X-Rspamd-Queue-Id: 398F8C0011 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1775836802-920319 X-HE-Meta: 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 7VKO4u7/ oUhCYHaoqQOSE9MNi0bkHLmFL0zBJXT/3bpNlFuKHci15IWoVwNkzhmjlsrPmkhWpJE6/wres4/iUXXW7VNtvx1uzv1A4mRxfG24VJ1/5Fn1csuphXk32VOrlOR/GRHmKGB3MOH1aNQCq1jB4OzE9vf/xYSY5t2bpvuY35yYWQrR8K/YkPqv+oFmoOeb0pbJ2a4QW7hNP4KXpIyARQI3YUtXGptf9g5pXHJEyiYi4Dbtnke09W5a2eub5jzPqKaPjc/+fyCZIlO2IwinR/WL7lZjcig== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Apr 08, 2026 at 04:23:01PM -0400, Luiz Capitulino wrote: >Shmem uses has_transparent_hugepage() in the following ways: > >- shmem_parse_one() and shmem_parse_huge(): Check if THP is built-in and > if the CPU supports PMD-sized pages > >- shmem_init(): Since the CONFIG_TRANSPARENT_HUGEPAGE guard is outside > the code block calling has_transparent_hugepage(), the > has_transparent_hugepage() call is exclusively checking if the CPU > supports PMD-sized pages > >While it's necessary to check if CONFIG_TRANSPARENT_HUGEPAGE is enabled >in all cases, shmem can determine mTHP size support at folio allocation >time. Therefore, drop has_transparent_hugepage() usage while keeping the >CONFIG_TRANSPARENT_HUGEPAGE checks. > >Signed-off-by: Luiz Capitulino >--- > mm/shmem.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > >diff --git a/mm/shmem.c b/mm/shmem.c >index b40f3cd48961..6f8b20d77e07 100644 >--- a/mm/shmem.c >+++ b/mm/shmem.c >@@ -689,7 +689,7 @@ static int shmem_parse_huge(const char *str) > else > return -EINVAL; > >- if (!has_transparent_hugepage() && >+ if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && > huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY) > return -EINVAL; > >@@ -4664,8 +4664,7 @@ static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param) > case Opt_huge: > ctx->huge = result.uint_32; > if (ctx->huge != SHMEM_HUGE_NEVER && >- !(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && >- has_transparent_hugepage())) >+ !IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) > goto unsupported_parameter; > ctx->seen |= SHMEM_SEEN_HUGE; > break; >@@ -5451,7 +5450,7 @@ void __init shmem_init(void) > #endif > > #ifdef CONFIG_TRANSPARENT_HUGEPAGE >- if (has_transparent_hugepage() && shmem_huge > SHMEM_HUGE_DENY) >+ if (shmem_huge > SHMEM_HUGE_DENY) > SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge; > else > shmem_huge = SHMEM_HUGE_NEVER; /* just in case it was patched */ >-- Although this patch simply drops the early has_transparent_hugepage() checks from the shmem parse/init paths, shmem_allowable_huge_orders() still returns 0 when thp_disabled_by_hw() is set. So on hardware without PMD THP support: unsigned long shmem_allowable_huge_orders(struct inode *inode, struct vm_area_struct *vma, pgoff_t index, loff_t write_end, bool shmem_huge_force) { ... if (thp_disabled_by_hw() || (vma && vma_thp_disabled(vma, vm_flags, shmem_huge_force))) return 0; ... } 1) the fault path still falls back to order-0 allocation 2) do_set_pmd() still falls back 3) khugepaged won't collapse it either Nothing jumped out at me, thanks! Reviewed-by: Lance Yang