From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-199.mta1.migadu.com [95.215.58.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E11053B42D7 for ; Mon, 17 Aug 2026 07:11:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786950704; cv=none; b=BDM6u6M0dWhw4iRR45kiIkLhHTUjn4qVw9Z5lia6FiWxA3+jgcUaShMfbq6fndwg1naIsvgrg3j8Akm2Slmgc0xB3DkRi4GU+PwbZKliVmKiFd8yU8gPqltEsyxyl6k2+Am1AAuRINUKIQRO4RGsjfZjFIrN8xzre79NQEzLn8o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786950704; c=relaxed/simple; bh=fD49dsTg8jKka6RcPvdvEUs8O3U0mhIuolE9NHAVDZ0=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=MMSnynIfwgUTYJxW8t3aj8ScUxKh8b1EyA1QvN66yZiM4KmqkZWXMbIlCxNcZCWpRQu9bOE1+hU2U+EtUYjJmzYCqD/QC0zYEq2/RefG5lVqPX1qnyw5RuTzKezXjQnYlohTgYlmcA+550nksx/J5IR8pPo9s1PAxMy4hxZ2Hy0= 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=Sobgg+Ef; arc=none smtp.client-ip=95.215.58.199 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="Sobgg+Ef" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=fD49dsTg8jKka6RcPvdvEUs8O3U0mhIuolE9NHAVDZ0=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1786950700; v=1; x=1787555500; b=Sobgg+EfinEhe27Skx7s7Ptq75J1IcSxpx3dyO2GbHaoiNuLnXznByHpQda28B2sAeWNNcLI Sz4oTRuy5GyIKBMZyJANLbLgW9hxL2N9QmOHEjUFoQtchs4v6sKeBMKNbl5W5pQrcmACRoM82f/ KMkusgGvkxjWwIbldaZd+mCM= X-Envelope-To: linux-kernel@vger.kernel.org Received: from teawater-KVM-Virtual-Machine (39.156.73.13) by smtp.migadu.com with ESMTPS id 8808c3c6d6410fc6; Mon, 17 Aug 2026 07:11:30 +0000 X-Migadu-Flow: FLOW_OUT From: "Hui Zhu" To: Andrew Morton , Kairui Song , Qi Zheng , Shakeel Butt , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Johannes Weiner , David Hildenbrand , Michal Hocko , Lorenzo Stoakes , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Hui Zhu Subject: [PATCH mm-unstable v2 0/2] mm/vmscan: fix NR_ISOLATED accounting and throttling for MGLRU Date: Mon, 17 Aug 2026 15:11:17 +0800 Message-ID: X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Hui Zhu The legacy reclaim path updates the NR_ISOLATED_ANON/FILE node counters around isolation and throttles direct reclaimers via too_many_isolated() when isolated folios pile up. The MGLRU eviction path does neither: evict_folios() isolates folios without touching the counters and never consults too_many_isolated(). Patch 1 updates NR_ISOLATED_ANON/FILE around isolation in evict_folios(), reusing the existing nr_isolated. Without this the counters stay at zero while MGLRU reclaim is active, so compaction's too_many_isolated() cannot see the pages MGLRU has isolated. Patch 2 extracts the throttling loop from shrink_inactive_list() into throttle_isolated() and calls it from evict_folios() as well, keeping the two reclaim paths unified, in line with what was done previously for writeback reclaim. This way the MGLRU eviction path is throttled when isolated folios pile up instead of thrashing the shrinking LRU lists - the scenario the too_many_isolated() check exists for. A dying task fakes reclaim progress exactly like the legacy path so it exits reclaim quickly. Testing ======= Test on 8G RAM qemu. The reproducer confines stress-ng workers in a 192M memcg and swaps through dm-delay (300ms write latency) so pageout is slow and isolated folios pile up; the workload is intentionally extreme to force the throttle path. Throttle events are counted via the mm_vmscan_throttled tracepoint. The test scripts and test log is in [1]. Test 1, reclaim throttling, parallel direct reclaim in the memcg: before after throttle events (ISOLATED) 0 512472 - from kswapd 0 0 nr_isolated_anon peak 0 3670 pswpout 3383673 87134 Without the series MGLRU reclaim swaps heavily while nr_isolated_* stays at 0 and nothing is throttled. With the series the counters are updated and direct reclaimers are throttled (the pswpout drop is the reclaimers backing off); kswapd stays exempt. Test 2, counters visible to compaction, same pressure plus compact_memory in parallel: before after nr_isolated peak 59 1093 The "before" 59 is compaction's own transient isolation; reclaim's isolation is invisible. With patch 1 it becomes visible to compaction's too_many_isolated(). (Compaction's own throttling threshold, (inactive + active) / 16, is ~23k pages on this box and needs more pile-up than the box can generate; test 1 exercises the same throttling mechanism end to end on the reclaim side.) [1] https://gist.github.com/teawater/d3968aac92eb6bd1378beb54a82933f4 Changelog: v2: Accoding to the commens of Kairun, Rebased on mm-unstable. Split into two patches; patch 2 is new and adds the too_many_isolated() throttling to the MGLRU eviction path, which v1 did not cover. Add test infomations. Hui Zhu (2): mm/vmscan: fix missing NR_ISOLATED counter update in MGLRU reclaim path mm/vmscan: apply too_many_isolated() throttling to MGLRU eviction mm/vmscan.c | 74 +++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 63 insertions(+), 11 deletions(-) -- 2.53.0