From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-113.freemail.mail.aliyun.com (out30-113.freemail.mail.aliyun.com [115.124.30.113]) (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 7810D18EFEC for ; Thu, 20 Jun 2024 08:26:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.113 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718872001; cv=none; b=nZPPobIf335L8oaiE6+HWrqkXW3+OeR+4473fMwVDl+h5Bwt0czOArimW2a6YZ6qQJxpNGodc3e4zMHFrpVnMgek7/+zcs7KsUqzFRtTwCHnrCqDWU6RzaRW6/G13yt4rPKHth7Ti3zOabNX+zzu95qK9LfwCXlO1jL+JxUhhuw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718872001; c=relaxed/simple; bh=v/K4VQme0bvsViQPwjOHP3RbmQFWbhgWUAPcoTTrvYc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=FQGU5W92lk+8vlR9P8ZZ1nQIXfS8heF1YVhwV0c+/TxTEGC+N9u4yl4RSLnxSxOHak93ar7pGW/UZ8uxdnkf6Qdj3Bdga6rEFCoUsdZnygzshUCMZwGfMwfCHPID7uT3yaMVs66uSkcT8JkNsH7s4xYZ+lSThE6Zh0pplkbtEBU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=KwPjxEsz; arc=none smtp.client-ip=115.124.30.113 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="KwPjxEsz" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1718871996; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=ygC+TzlChiS7e/5qCa3pXxwNm9uFHomfKyMe5wbEsQY=; b=KwPjxEsz6sXh8ovh3uPVQytTdZQYYXWN1oSD78UnJ7i/yZiLihQAJsjOzSOA0qxbt2+9BFPgI3yuCtVFMeQVAJ7eA5tvlLvx6MhKe7fTNBUdj9xzgtHm2ju9eH1eL9mSCxzW/Fdck+5kfd5nzGEZmnzc1o2U9Z7AHpk4pdEZfFA= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033045046011;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=17;SR=0;TI=SMTPD_---0W8qePrm_1718871994; Received: from 30.97.56.69(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0W8qePrm_1718871994) by smtp.aliyun-inc.com; Thu, 20 Jun 2024 16:26:35 +0800 Message-ID: <2d778151-9b8c-4be8-a4d3-bafcc1f09778@linux.alibaba.com> Date: Thu, 20 Jun 2024 16:26:33 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/9] mm: vmscan: add validation before spliting shmem large folio To: Yu Zhao Cc: akpm@linux-foundation.org, hughd@google.com, willy@infradead.org, david@redhat.com, wangkefeng.wang@huawei.com, chrisl@kernel.org, ying.huang@intel.com, 21cnbao@gmail.com, ryan.roberts@arm.com, shy828301@gmail.com, ziy@nvidia.com, ioworker0@gmail.com, da.gomez@samsung.com, p.raghav@samsung.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <413866f2f2d996cfbb5c906467b36c96b1a82e2d.1718690645.git.baolin.wang@linux.alibaba.com> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2024/6/20 14:12, Yu Zhao wrote: > On Tue, Jun 18, 2024 at 12:54 AM Baolin Wang > wrote: >> >> Add swap available space validation before spliting shmem large folio to >> avoid redundant split, since we can not write shmem folio to the swap device >> in this case. > > We don't scan anon LRU unless we know we may be able to swap. Even if > there is swap space, we may still not be able to swap. See > can_reclaim_anon_pages(). Right. Another case is MADV_PAGEOUT can still split a large shmem folio even without a swap device. I know this is not a common case, and I can drop this patch if it is less helpful. Thanks for your input. >> Signed-off-by: Baolin Wang >> --- >> mm/vmscan.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/mm/vmscan.c b/mm/vmscan.c >> index 1807e5d95dda..61465f92283f 100644 >> --- a/mm/vmscan.c >> +++ b/mm/vmscan.c >> @@ -1237,6 +1237,14 @@ static unsigned int shrink_folio_list(struct list_head *folio_list, >> } >> } else if (folio_test_swapbacked(folio) && >> folio_test_large(folio)) { >> + >> + /* >> + * Do not split shmem folio if no swap memory >> + * available. >> + */ >> + if (!total_swap_pages) >> + goto activate_locked; >> + >> /* Split shmem folio */ >> if (split_folio_to_list(folio, folio_list)) >> goto keep_locked; >> -- >> 2.39.3 >> >>