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 BBC0CCAC587 for ; Tue, 9 Sep 2025 05:58:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 251FF8E0008; Tue, 9 Sep 2025 01:58:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 228E88E0001; Tue, 9 Sep 2025 01:58:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1661D8E0008; Tue, 9 Sep 2025 01:58:33 -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 046C58E0001 for ; Tue, 9 Sep 2025 01:58:33 -0400 (EDT) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 910CC13AAD1 for ; Tue, 9 Sep 2025 05:58:32 +0000 (UTC) X-FDA: 83868657264.29.B51849F Received: from out30-99.freemail.mail.aliyun.com (out30-99.freemail.mail.aliyun.com [115.124.30.99]) by imf24.hostedemail.com (Postfix) with ESMTP id 36B5018000D for ; Tue, 9 Sep 2025 05:58:28 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b=gFUO10Cm; spf=pass (imf24.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.99 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com; dmarc=pass (policy=none) header.from=linux.alibaba.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1757397510; 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=btmA0dgras/e+IP/547OTg6AjeVnYhqLnZKh6bgWqc4=; b=3/JNGuhQzdRL7uWdvFtmR1uBdtZ/IDk9oEUURiq1FVna20ugUt8iFr0Ei3S4m4fwTiGJWf cwIJ6+aeYeZgpmDR4Wh5GBQ5zapgMncyyF8bCrXuZC5PhYClZZKVe0nInDvVKx1qcWlhDg 22/bQHQORh4oc1Kowwl+VH7ZvsAMC/E= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1757397510; a=rsa-sha256; cv=none; b=lZpl02Qtk+zco0MZPjiYqoUcYbgOLqNwItubLozNCyFInRYkw+NYhHI3Sh7eFN61WmPeDm 6+u+pG1tAqvxa3gIVP7+eSTfBz+XG4V5t1ah/QYHWrR15ScBZMcSdZXioAa/+EQRYdQFMr WoPKRJiAc0v8xEFud9SH0HK6RWmiu5s= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=linux.alibaba.com header.s=default header.b=gFUO10Cm; spf=pass (imf24.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.99 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com; dmarc=pass (policy=none) header.from=linux.alibaba.com DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1757397505; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=btmA0dgras/e+IP/547OTg6AjeVnYhqLnZKh6bgWqc4=; b=gFUO10Cma+EsKe1zZcHp1IQZD1AYQm6BGkvNuyF5yBqhwuRn5nfbqXyYPH7j4yRUCbS81eDfnIHmCFuh5F22fBJK0HFUlw/Q/Aw7624tH3ZWs6C2+EmibSK8kN4Iqr4qXdBhMFgEbjlna/KX5nVmafb1dT+FswxbDFCt7dvMNVo= Received: from 30.74.144.127(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Wncf147_1757397504 cluster:ay36) by smtp.aliyun-inc.com; Tue, 09 Sep 2025 13:58:24 +0800 Message-ID: Date: Tue, 9 Sep 2025 13:58:22 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: shmem: fix too little space for tmpfs only fallback 4KB To: Vernon Yang , hughd@google.com, akpm@linux-foundation.org, da.gomez@samsung.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vernon Yang References: <20250908123128.900254-1-vernon2gm@gmail.com> From: Baolin Wang In-Reply-To: <20250908123128.900254-1-vernon2gm@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 36B5018000D X-Stat-Signature: 5jofknq6neoyps3fdpoj67gdkjbeq43h X-Rspam-User: X-HE-Tag: 1757397508-514875 X-HE-Meta: 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 ldlChnyL yP63LTQbrY0cxcsP3D/iNcPZF0/PpFnGuYmjo94SbZ8tI9NeScG/jrIM6Qb4YJAmklSibzU2z8TCqQVlohLM9MYOK7Nq+51NBGa/IbPrl/8FzwEa7IgImNNiQCDPJf95k2vu29ZOhUXVRKQEL0SbMsI3ZPjTEDtdzXTyGzFbSmYFPeFXQhAdl7zu5ZVmJCGmg6BqgzGsYB9gLytf0ES6NKSex8H2ec5cxa8/zAuKxVzNrjckkgJ1Jldk5AkwuAAfY0JK3SFC4Kl9dt4Jy8P5k0Zgkhg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2025/9/8 20:31, Vernon Yang wrote: > From: Vernon Yang > > When the system memory is sufficient, allocating memory is always > successful, but when tmpfs size is low (e.g. 1MB), it falls back > directly from 2MB to 4KB, and other small granularity (8KB ~ 1024KB) > will not be tried. > > Therefore add check whether the remaining space of tmpfs is sufficient > for allocation. If there is too little space left, try smaller large > folio. I don't think so. For a tmpfs mount with 'huge=within_size' and 'size=1M', if you try to write 1M data, it will allocate an order 8 large folio and will not fallback to order 0. For a tmpfs mount with 'huge=always' and 'size=1M', if you try to write 1M data, it will not completely fallback to order 0 either, instead, it will still allocate some order 1 to order 7 large folios. I'm not sure if this is your actual user scenario. If your files are small and you are concerned about not getting large folio allocations, I recommend using the 'huge=within_size' mount option. > Fixes: acd7ccb284b8 ("mm: shmem: add large folio support for tmpfs") No, this doesn't fix anything. > Signed-off-by: Vernon Yang > --- > mm/shmem.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/mm/shmem.c b/mm/shmem.c > index 8c592c6db2a0..b20affd57b23 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -1820,6 +1820,7 @@ static unsigned long shmem_suitable_orders(struct inode *inode, struct vm_fault > unsigned long orders) > { > struct vm_area_struct *vma = vmf ? vmf->vma : NULL; > + struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); > pgoff_t aligned_index; > unsigned long pages; > int order; > @@ -1835,6 +1836,18 @@ static unsigned long shmem_suitable_orders(struct inode *inode, struct vm_fault > while (orders) { > pages = 1UL << order; > aligned_index = round_down(index, pages); > + > + /* > + * Check whether the remaining space of tmpfs is sufficient for > + * allocation. If there is too little space left, try smaller > + * large folio. > + */ > + if (sbinfo->max_blocks && percpu_counter_read(&sbinfo->used_blocks) > + + pages > sbinfo->max_blocks) { > + order = next_order(&orders, order); > + continue; > + } > + > /* > * Check for conflict before waiting on a huge allocation. > * Conflict might be that a huge page has just been allocated