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 AA2E0F8FA90 for ; Tue, 21 Apr 2026 15:25:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1065E6B0005; Tue, 21 Apr 2026 11:25:47 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0B7A36B0088; Tue, 21 Apr 2026 11:25:47 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EE84F6B0089; Tue, 21 Apr 2026 11:25:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id DCAC46B0005 for ; Tue, 21 Apr 2026 11:25:46 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 88D5713C4FA for ; Tue, 21 Apr 2026 15:25:46 +0000 (UTC) X-FDA: 84682937892.21.0A89451 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by imf24.hostedemail.com (Postfix) with ESMTP id F13BC180009 for ; Tue, 21 Apr 2026 15:25:43 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=ibm.com header.s=pp1 header.b=FAs2zFY+; spf=pass (imf24.hostedemail.com: domain of donettom@linux.ibm.com designates 148.163.158.5 as permitted sender) smtp.mailfrom=donettom@linux.ibm.com; dmarc=pass (policy=none) header.from=ibm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1776785144; a=rsa-sha256; cv=none; b=WG1iRasEumjyUS+c1uP4i1iPxOhYk1m/+rOuWeVz4GvBIb2uu1b7b1ksH5mavz7CK/Ng4R KyStVgzvNo8lKZ6qwK9SnSpyf9zaObEQiiOwzMsRW0ytWE3ZENZYLfjF3UmVTeILwdItWa mvPlOXIXRPp+K721ccOQ0txGI5OBr5g= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=ibm.com header.s=pp1 header.b=FAs2zFY+; spf=pass (imf24.hostedemail.com: domain of donettom@linux.ibm.com designates 148.163.158.5 as permitted sender) smtp.mailfrom=donettom@linux.ibm.com; dmarc=pass (policy=none) header.from=ibm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1776785144; 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=o1X9HPUunIQebJ9dADNmZa8MGaML1kJb/aSg0TZlqss=; b=Pt5oCFZm1oD5klj0QVjzT4Sx6q9w9xKGPWAw9elif9Z241QV/NQPmtRe3rYPMbjjEofsQe 3/RydtW6TlmyMelQisOBtETlm++W00668G6/QvfUfrThJZo0sUCUdlModhwYMu0W/jyXuu 3QI485PeF0plMy2oojfcTxN5iA3X+5Y= Received: from pps.filterd (m0356516.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 63LCfPbw2037844; Tue, 21 Apr 2026 15:25:18 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=o1X9HP UunIQebJ9dADNmZa8MGaML1kJb/aSg0TZlqss=; b=FAs2zFY+seMt5J/wyEvwcX J3Qs8AwdungWDk3ceTc+T4bf52oCVAr6pcSg2BEuFhAbv4HC2tLuNgFyIeZr+QLJ TQnT55zXAcFJmtfxkeJgd9xLQ7/mincVEMir+evb5W0ea9ZUOidUn/zHK+wFDIrw JWAibdWC0syZd+iTkgK8zRTqTNZdMofijb/NY5ONihNSI6ZgTB1MKhkVyx2oWIdj w7uhA2JyL4Jw35Ss+CKEOwng6W5CIb4tItaeiB/gNH7sFF/2SJHfjwtX11FVuBpL VV7EEsGVHIcheQEGKsvOjuFDnwGhD3/gYNi2uhQRLoc+omR3VBZiXbtRYOTrN48w == Received: from ppma23.wdc07v.mail.ibm.com (5d.69.3da9.ip4.static.sl-reverse.com [169.61.105.93]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4dm2h9m78b-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 21 Apr 2026 15:25:17 +0000 (GMT) Received: from pps.filterd (ppma23.wdc07v.mail.ibm.com [127.0.0.1]) by ppma23.wdc07v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 63LFKWUP013111; Tue, 21 Apr 2026 15:25:16 GMT Received: from smtprelay05.wdc07v.mail.ibm.com ([172.16.1.72]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4dmnsh15y7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 21 Apr 2026 15:25:16 +0000 (GMT) Received: from smtpav04.dal12v.mail.ibm.com (smtpav04.dal12v.mail.ibm.com [10.241.53.103]) by smtprelay05.wdc07v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 63LFPGGU23069246 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 21 Apr 2026 15:25:16 GMT Received: from smtpav04.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3635D5805A; Tue, 21 Apr 2026 15:25:16 +0000 (GMT) Received: from smtpav04.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3EA1258052; Tue, 21 Apr 2026 15:25:05 +0000 (GMT) Received: from [9.124.216.216] (unknown [9.124.216.216]) by smtpav04.dal12v.mail.ibm.com (Postfix) with ESMTP; Tue, 21 Apr 2026 15:25:04 +0000 (GMT) Message-ID: <24cd6a95-1304-4732-9273-43c73ea858b2@linux.ibm.com> Date: Tue, 21 Apr 2026 20:55:02 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v6 2/5] mm: migrate: Add migrate_misplaced_folios_batch() To: Bharata B Rao , linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Jonathan.Cameron@huawei.com, dave.hansen@intel.com, gourry@gourry.net, mgorman@techsingularity.net, mingo@redhat.com, peterz@infradead.org, raghavendra.kt@amd.com, riel@surriel.com, rientjes@google.com, sj@kernel.org, weixugc@google.com, willy@infradead.org, ying.huang@linux.alibaba.com, ziy@nvidia.com, dave@stgolabs.net, nifan.cxl@gmail.com, xuezhengchu@huawei.com, yiannis@zptcorp.com, akpm@linux-foundation.org, david@redhat.com, byungchul@sk.com, kinseyho@google.com, joshua.hahnjy@gmail.com, yuanchu@google.com, balbirs@nvidia.com, alok.rathore@samsung.com, shivankg@amd.com References: <20260323095104.238982-1-bharata@amd.com> <20260323095104.238982-3-bharata@amd.com> Content-Language: en-US From: Donet Tom In-Reply-To: <20260323095104.238982-3-bharata@amd.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: qy8g05uTAlspSHaPFCbZfBJNS4O0FSOV X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDIxMDE1MyBTYWx0ZWRfX2lvX/8LD+K4d RxWH048hje3Sxp6jwSK9U+ofRWqaJ2KqvssfLkKvBIcoAAZ6VbGYdw99UcNhpmsEaVY+sZZr/5B q+7CxLE9JpALKcgc6JJJq6/lzY4Ipp21AD3fCATiw9eoioquHyE+latF7yEUg5n0H5ufgNI950l rn9rjhI8y/1qf5pFhEOHe8AO3WO5TRiNN7Hjqc1qTz9sf3UJ7zX0zlTP2WhPHrHdMXKpeJA97DK dYkdenDIo/am88ssDl66h6YegxX+lVFVEs68hOu7ND3ECfimi54mnt6Nh4lCSFN5hOjO5OW07dj g/myM9Uag1o0CKslaiYKPUAikeZ63nbJLFvy7xHByWHq/krqUSTr52cZRNO8CJw/XzMkDj5NyV8 kSqcgW5ckIm+kiAjPi1YmO99WmYnUeeJMwTIQPC70WCwyrfVpSAWV4md7GbeqoA5m7efu9Fx/LY lF1jCtdn5kuHhlbFu2Q== X-Authority-Analysis: v=2.4 cv=XLYAjwhE c=1 sm=1 tr=0 ts=69e796de cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=tHa68p0SAAAA:8 a=zd2uoN0lAAAA:8 a=3BaletrFva9TSh3rlm0A:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=ufIsyHvWW7FwcMbVRpPq:22 X-Proofpoint-GUID: nRk-v5W9kOPmZ-0ggMcpCYROJyC80wZF X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-21_03,2026-04-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 bulkscore=0 impostorscore=0 spamscore=0 adultscore=0 priorityscore=1501 phishscore=0 lowpriorityscore=0 malwarescore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604070000 definitions=main-2604210153 X-Rspamd-Queue-Id: F13BC180009 X-Stat-Signature: jb5tro47zeiah6z3msnbj38wi4g7yhqu X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1776785143-172820 X-HE-Meta: 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 g9FjEvn/ QEpVitYgGxrQyNEegZm9fCfaPdO40h8mnlUkMbRlJ4ixQg6yO33W74ZSKBIZsybc0kcgt93PVUu6bKyL6M9EwiQjR9jaJFh1FowRg9X+6tGkQtCPMF1664uKSZ47Pro+uVaSF4ig8Nqkzwz8freaGRlGTgJx1VKmZzkoxv4i2sAMG0Gbii27G0XBNGywtKB0SsrCRplXsg5nTOQCNvU8+ZJMGeqWIIsWpbv4+MUQIOXqJ1XmPuYa9NbW1RGQhLxFLV4qYmNLrEIvMJ4YUAY5HL/SA59+Yi3Ro5PcBtabk7wOSSy1SbT2TdjOwN5QzMyKTOIf0+4+8q2b3BovabSKdHvyA1YIUB7Wv4MQCqkATOj3vndxD2XfJ/9PbB1y4xyr474cCmpo6das+8lR1Hl7C/3U4c01pnVULB6t7FLUWw+LUzr8UiLG5QsG5P0b31Jn+BvnmzoczOt0nokkyMN2doLjjmwod6HnUxWVw+kgNhRGbAnw= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Bharata On 3/23/26 3:21 PM, Bharata B Rao wrote: > From: Gregory Price > > Tiered memory systems often require migrating multiple folios at once. > Currently, migrate_misplaced_folio() handles only one folio per call, > which is inefficient for batch operations. This patch introduces > migrate_misplaced_folios_batch(), a batch variant that leverages > migrate_pages() internally for improved performance. > > The caller must isolate folios beforehand using > migrate_misplaced_folio_prepare(). On return, the folio list will be > empty regardless of success or failure. > > This function will be used by pghot kmigrated thread. > > Signed-off-by: Gregory Price > [Rewrote commit description] > Signed-off-by: Bharata B Rao > --- > include/linux/migrate.h | 6 ++++++ > mm/migrate.c | 48 +++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 54 insertions(+) > > diff --git a/include/linux/migrate.h b/include/linux/migrate.h > index d5af2b7f577b..5c1e2691cec2 100644 > --- a/include/linux/migrate.h > +++ b/include/linux/migrate.h > @@ -111,6 +111,7 @@ static inline void softleaf_entry_wait_on_locked(softleaf_t entry, spinlock_t *p > int migrate_misplaced_folio_prepare(struct folio *folio, > struct vm_area_struct *vma, int node); > int migrate_misplaced_folio(struct folio *folio, int node); > +int migrate_misplaced_folios_batch(struct list_head *folio_list, int node); > #else > static inline int migrate_misplaced_folio_prepare(struct folio *folio, > struct vm_area_struct *vma, int node) > @@ -121,6 +122,11 @@ static inline int migrate_misplaced_folio(struct folio *folio, int node) > { > return -EAGAIN; /* can't migrate now */ > } > +static inline int migrate_misplaced_folios_batch(struct list_head *folio_list, > + int node) > +{ > + return -EAGAIN; /* can't migrate now */ > +} > #endif /* CONFIG_NUMA_BALANCING */ > > #ifdef CONFIG_MIGRATION > diff --git a/mm/migrate.c b/mm/migrate.c > index a15184950e65..94daec0f49ef 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -2751,5 +2751,53 @@ int migrate_misplaced_folio(struct folio *folio, int node) > BUG_ON(!list_empty(&migratepages)); > return nr_remaining ? -EAGAIN : 0; > } > + > +/** > + * migrate_misplaced_folios_batch() - Batch variant of migrate_misplaced_folio > + * Attempts to migrate a folio list to the specified destination. > + * @folio_list: Isolated list of folios to be batch-migrated. > + * @node: The NUMA node ID to where the folios should be migrated. > + * > + * Caller is expected to have isolated the folios by calling > + * migrate_misplaced_folio_prepare(), which will result in an > + * elevated reference count on the folio. All the isolated folios > + * in the list must belong to the same memcg so that NUMA_PAGE_MIGRATE > + * stat can be attributed correctly to the memcg. > + * > + * This function will un-isolate the folios, drop the elevated reference > + * and remove them from the list before returning. This is called > + * only for batched promotion of hot pages from lower tier nodes. > + * > + * Return: 0 on success and -EAGAIN on failure or partial migration. > + * On return, @folio_list will be empty regardless of success/failure. > + */ > +int migrate_misplaced_folios_batch(struct list_head *folio_list, int node) > +{ > + pg_data_t *pgdat = NODE_DATA(node); > + struct mem_cgroup *memcg = NULL; > + unsigned int nr_succeeded = 0; > + int nr_remaining; > + > + if (!list_empty(folio_list)) { > We seem to proceed even when the list is empty. Should we instead return early in that case? > + struct folio *first = list_first_entry(folio_list, struct folio, lru); > + memcg = get_mem_cgroup_from_folio(first); I had a small question—are we ensuring that a single list contains folios from the same memcg? -Donet > + } > + > + nr_remaining = migrate_pages(folio_list, alloc_misplaced_dst_folio, > + NULL, node, MIGRATE_ASYNC, > + MR_NUMA_MISPLACED, &nr_succeeded); > + if (nr_remaining) > + putback_movable_pages(folio_list); > + > + if (nr_succeeded) { > + count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded); > + mod_node_page_state(pgdat, PGPROMOTE_SUCCESS, nr_succeeded); > + count_memcg_events(memcg, NUMA_PAGE_MIGRATE, nr_succeeded); > + } > + > + mem_cgroup_put(memcg); > + WARN_ON(!list_empty(folio_list)); > + return nr_remaining ? -EAGAIN : 0; > +} > #endif /* CONFIG_NUMA_BALANCING */ > #endif /* CONFIG_NUMA */