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 C44F0E9D814 for ; Tue, 7 Apr 2026 06:49:20 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F15726B0089; Tue, 7 Apr 2026 02:49:19 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EEC9A6B008A; Tue, 7 Apr 2026 02:49:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E29F86B008C; Tue, 7 Apr 2026 02:49:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id D16706B0089 for ; Tue, 7 Apr 2026 02:49:19 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 5AD871406D9 for ; Tue, 7 Apr 2026 06:49:19 +0000 (UTC) X-FDA: 84630833238.23.7ABDEB7 Received: from out-177.mta0.migadu.com (out-177.mta0.migadu.com [91.218.175.177]) by imf18.hostedemail.com (Postfix) with ESMTP id 5D9281C000D for ; Tue, 7 Apr 2026 06:49:17 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="WERdu//K"; spf=pass (imf18.hostedemail.com: domain of lance.yang@linux.dev designates 91.218.175.177 as permitted sender) smtp.mailfrom=lance.yang@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1775544557; a=rsa-sha256; cv=none; b=HPkS9b3S4Zzw+7ffM+tJO8hkt+KyQqvu3BzbuSW14edAuCKjBUHQXMU2UX9tsMaoyhCvSP GUQVALtE4WMcm63ETg/Rjs+RBUupkJKuRN3XawJJpCxrqrz6WlKUR+rPjhFx4q+ipYFInH Ku4mmpsGPNV1HRClsB5n2KWVlCsbyBo= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1775544557; 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=XZeY293QSxwS94/+8C2N9QAoOiUfZiEZF2lGyKP5AKE=; b=BrTCjTVHNNWSKJX9Xi/7mfNba4AWXk3nuuZvKsAgZs/Ut8FgEKKevpGYiLJ951C2BXYTL7 TmblYv2lIMF2kfuepaG+xSQZ6B0M7a1jCI0WvIqtxHgtcylO19xtSc/zsNlFKNrCD71eaT rCnZKhAooh4sTdNEx1RI9CjnZsVsr5Q= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="WERdu//K"; spf=pass (imf18.hostedemail.com: domain of lance.yang@linux.dev designates 91.218.175.177 as permitted sender) smtp.mailfrom=lance.yang@linux.dev; dmarc=pass (policy=none) header.from=linux.dev 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=1775544555; 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=XZeY293QSxwS94/+8C2N9QAoOiUfZiEZF2lGyKP5AKE=; b=WERdu//KTfuanPQswZOKAavLD5SrF/saVav3K5wcfXSgigtMYYuOALt64YernykprSFtXw i6mFsg7QITLNACQ68Yf6b8XHZqhXqSBB4xHFlQ9UfOi3vFvZVPltkhALZ5vTUoXQl+OyL8 Jt17LZjfw2Dt1Pu2fMhJm5px5C1wyKk= From: Lance Yang To: baolin.wang@linux.alibaba.com Cc: akpm@linux-foundation.org, hughd@google.com, willy@infradead.org, ziy@nvidia.com, david@kernel.org, ljs@kernel.org, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: shmem: don't set large-order range for internal anonymous shmem mapping Date: Tue, 7 Apr 2026 14:49:03 +0800 Message-Id: <20260407064903.69017-1-lance.yang@linux.dev> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 5D9281C000D X-Stat-Signature: qkgc5pfeu8m51cz4hdjf3qd7qsrenwnr X-HE-Tag: 1775544557-922868 X-HE-Meta: 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 OZ3mQMye 3URoLndLHDjRB3l8uESXMH8mOE/1Xm9IsajNks+lxwUZA7pAvrCJMMws5/EAO2sL+KzMI+zwmKgq89XiQ4h7e86rmdrxVoseY96Mr+l63NLanlBX0Ac+vRSzKPBPqX5ASJdn5C9yK9Ngs1dw2QSVCOLnHBMCF2CCVOlvOIz+YE71gHwWVay9TUkg8Zs6FTczAWhROaFffYu2z2ADVKP0EhCUeyCDF++fon8+ZYQaAFE/xfM8fqQmkDsntgtyCWEYhV7lH Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Apr 07, 2026 at 02:07:27PM +0800, Baolin Wang wrote: >Anonymous shmem large order allocations are dynamically controlled via the >global THP sysfs knob (/sys/kernel/mm/transparent_hugepage/shmem_enabled) >and the per-size mTHP knobs (/sys/kernel/mm/transparent_hugepage/hugepages-kB/shmem_enabled). > >Therefore, anonymous shmem uses shmem_allowable_huge_orders() to check >which large orders are allowed, rather than relying on mapping_max_folio_order(). >Moreover, mapping_max_folio_order() is intended to control large order >allocations only for tmpfs mounts. Clarify this by not setting a large-order >range for internal anonymous shmem mappings, to avoid confusion, as discussed >in the previous thread[1]. > >[1] https://lore.kernel.org/all/ec927492-4577-4192-8fad-85eb1bb43121@linux.alibaba.com/ >Signed-off-by: Baolin Wang >--- > mm/shmem.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > >diff --git a/mm/shmem.c b/mm/shmem.c >index 4ecefe02881d..a60fe067969c 100644 >--- a/mm/shmem.c >+++ b/mm/shmem.c >@@ -3088,8 +3088,17 @@ static struct inode *__shmem_get_inode(struct mnt_idmap *idmap, > if (sbinfo->noswap) > mapping_set_unevictable(inode->i_mapping); > >- /* Don't consider 'deny' for emergencies and 'force' for testing */ >- if (sbinfo->huge) >+ /* >+ * Only set the large order range for tmpfs mounts. The large order >+ * selection for the internal anonymous shmem mount is configured >+ * dynamically via the 'shmem_enabled' interfaces, so there is no >+ * need to set a large order range for the internal anonymous shmem >+ * mapping. >+ * >+ * Note: Don't consider 'deny' for emergencies and 'force' for >+ * testing. >+ */ >+ if (sbinfo->huge && !(sb->s_flags & SB_KERNMOUNT)) FWIW, SB_KERNMOUNT is broader than "internal anonymous shmem" and covers all shm_mnt users too. So maybe "internal shmem mount" would be a better description of what this code is actually checking. > mapping_set_large_folios(inode->i_mapping); > > switch (mode & S_IFMT) { Cheers, Lance