From nobody Thu Oct 2 11:50:40 2025 Received: from out30-131.freemail.mail.aliyun.com (out30-131.freemail.mail.aliyun.com [115.124.30.131]) (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 7C80B213236 for ; Thu, 18 Sep 2025 03:47:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758167229; cv=none; b=o7IGdRGKJ+/SA+egUcqp3DEI099/vB+mtHOdKvVvZ0zo8un0al6/ohTwLCxw81M6TC7TIBMs+/17myhSEHAU6lBuXBjxzreFZTvSi7QbUztvnaFsip6Z03TDpKQfiDEfLbtZqS9kyTrtmkBbNxH31nkvTku2cNTIYMuYmeVT0LE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758167229; c=relaxed/simple; bh=akkZKE5MYie+IE+BkOfIF24QBc/GBSowC6Wc116V1nc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BxXAeyKvfQLfqkCFqtj7z3CB67eTUF6veE2bMH8IiVCEZaxnE5Mlae3GVa3DHXApkd64ieBiXbUdr9BdeTkpd1P21bnr5og8JCn5husB/nI737Ihvzln58oi8DX6C7NllLI2oXqp6bXPhVShJtBKG8hskYGEQjJG5NkOAWHMVzo= 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=JvbQ3sPl; arc=none smtp.client-ip=115.124.30.131 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="JvbQ3sPl" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1758167225; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=RTSPriXkykSZAqFc/d3pFWgXfbyl1hq/sl6Tq3Oc8Jo=; b=JvbQ3sPlT3HWknW0YBv4jXaEM1RWp8ghfhtGRjZnAOXKs/YX1SEoa84a3xzg1n3t7ybTyEqAhU6QwUWsh8SRa9g8VQ3mEx6SAYuFbijHFmPwRKBw0M6AYselvU0tWA6YKLNdiDf78XVb8v3zLIHemNvl2aJ15FeZSrkNjcP2oaE= Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0WoEWeJK_1758167222 cluster:ay36) by smtp.aliyun-inc.com; Thu, 18 Sep 2025 11:47:03 +0800 From: Baolin Wang To: akpm@linux-foundation.org, hannes@cmpxchg.org Cc: david@redhat.com, mhocko@kernel.org, zhengqi.arch@bytedance.com, shakeel.butt@linux.dev, lorenzo.stoakes@oracle.com, hughd@google.com, willy@infradead.org, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 2/2] mm: vmscan: simplify the folio refcount check in pageout() Date: Thu, 18 Sep 2025 11:46:54 +0800 Message-ID: <4cbbec5bb92397aa4597105f1f499aabf7a1901c.1758166683.git.baolin.wang@linux.alibaba.com> X-Mailer: git-send-email 2.43.7 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Since we no longer attempt to write back filesystem folios in pageout() (they will be filtered out by the following check in pageout()), and only tmpfs/shmem folios and anonymous swapcache folios can be written back, we can remove the redundant folio_test_private() when checking the folio's refcount, as tmpfs/shmem and swapcache folios do not use the PG_private fla= g. While we're at it, we can open-code the folio refcount check instead of adding a simple helper that has only one user. Acked-by: David Hildenbrand Acked-by: Shakeel Butt Signed-off-by: Baolin Wang --- mm/vmscan.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 930add6d90ab..b3a57db6a445 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -477,17 +477,6 @@ static int reclaimer_offset(struct scan_control *sc) return PGSTEAL_DIRECT - PGSTEAL_KSWAPD; } =20 -static inline int is_page_cache_freeable(struct folio *folio) -{ - /* - * A freeable page cache folio is referenced only by the caller - * that isolated the folio, the page cache and optional filesystem - * private data at folio->private. - */ - return folio_ref_count(folio) - folio_test_private(folio) =3D=3D - 1 + folio_nr_pages(folio); -} - /* * We detected a synchronous write error writing a folio out. Probably * -ENOSPC. We need to propagate that into the address_space for a subseq= uent @@ -696,8 +685,11 @@ static pageout_t pageout(struct folio *folio, struct a= ddress_space *mapping, * block, for some throttling. This happens by accident, because * swap_backing_dev_info is bust: it doesn't reflect the * congestion state of the swapdevs. Easy to fix, if needed. + * + * A freeable shmem or swapcache folio is referenced only by the + * caller that isolated the folio and the page cache. */ - if (!is_page_cache_freeable(folio)) + if (folio_ref_count(folio) !=3D 1 + folio_nr_pages(folio)) return PAGE_KEEP; if (!mapping) { /* --=20 2.43.7