From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-173.mta1.migadu.com (out-173.mta1.migadu.com [95.215.58.173]) (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 136DC3B7B8F for ; Fri, 27 Mar 2026 07:29:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774596575; cv=none; b=fuG9eVcGBgzJNvKBmEJp3Y0cmmprXZ/w8HgVCZvSbr7eHYg0dbc1UEKclO6DlaCDsEQANx0N3v/EJ4Zp/Oon8WpL5EMKkmbbT417T4qAaF+cWafkDznLYCPtxVLKWsUlnfmaPQgiPcmU0t3XOgpkjiemivzvMRlSVVYKqN4Tmtw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774596575; c=relaxed/simple; bh=9lurGn1lSpzBgjH0/+dePgyNKRaFTinujHYU3qgSCgw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=hYSVmf1QIsds3gB4DvV4uftwJ05DCkvxUdpBxrQnpBIsayc8bBX84Q8epGNO6Dd3dNSAD8mvpyrXlQdQE0Uegg64776uNf5ZbccEtdfw/jwZkM9PtZifj09m6B6D8/6xmiGYMe7zy0UZ5SBLi+8Emaq08tjT7itTmEedgerRjTw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=ox3nCwo8; arc=none smtp.client-ip=95.215.58.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="ox3nCwo8" 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=1774596565; 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=8PVUMllx9roLVYGuErAn8ZTvJWl2ucu/IWwrTH7LZxM=; b=ox3nCwo83xjPmHsH25jtZvfi47UYkpcpsgdfU0K+K5oldz/OcHPPSHjnn5pFX42Wls5vXc rNFIQR8MoOh0foEg6JFagB5C7tnJiClvkiS15v7LnC6EeNv12LdziqkhNU90QcKELv89uZ YGP/nfRe6E9BvTuukXmXKEdDLOc/mbQ= From: Lance Yang To: ziy@nvidia.com Cc: willy@infradead.org, songliubraving@fb.com, clm@fb.com, dsterba@suse.com, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, shuah@kernel.org, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v1 02/10] mm/khugepaged: remove READ_ONLY_THP_FOR_FS check Date: Fri, 27 Mar 2026 15:29:17 +0800 Message-Id: <20260327072917.68630-1-lance.yang@linux.dev> In-Reply-To: <20260327014255.2058916-3-ziy@nvidia.com> References: <20260327014255.2058916-3-ziy@nvidia.com> Precedence: bulk X-Mailing-List: linux-fsdevel@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-Migadu-Flow: FLOW_OUT On Thu, Mar 26, 2026 at 09:42:47PM -0400, Zi Yan wrote: >collapse_file() requires FSes supporting large folio with at least >PMD_ORDER, so replace the READ_ONLY_THP_FOR_FS check with that. shmem with >huge option turned on also sets large folio order on mapping, so the check >also applies to shmem. > >While at it, replace VM_BUG_ON with returning failure values. > >Signed-off-by: Zi Yan >--- > mm/khugepaged.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > >diff --git a/mm/khugepaged.c b/mm/khugepaged.c >index d06d84219e1b..45b12ffb1550 100644 >--- a/mm/khugepaged.c >+++ b/mm/khugepaged.c >@@ -1899,8 +1899,11 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr, > int nr_none = 0; > bool is_shmem = shmem_file(file); > >- VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); >- VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); >+ /* "huge" shmem sets mapping folio order and passes the check below */ >+ if (mapping_max_folio_order(mapping) < PMD_ORDER) >+ return SCAN_FAIL; Yep, for shmem inodes, if the mount has huge= enabled, inode creation marks the mapping are large-folio capable: /* Don't consider 'deny' for emergencies and 'force' for testing */ if (sbinfo->huge) mapping_set_large_folios(inode->i_mapping); LGTM! Reviewed-by: Lance Yang