From nobody Wed Dec 17 14:23:31 2025 Received: from m16.mail.126.com (m16.mail.126.com [220.197.31.7]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 2E5512BCF5; Tue, 17 Dec 2024 03:33:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.7 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734406441; cv=none; b=jm+gnQEZmlIq2r/aMF9NHhw8kWDa6MR/QtmmC76XrJxFzhBYuX0XEOr8PR9cO5QqlhmNH9QJwX4qkh4QEkqDzE4cfyiPyOTm+wn1f9Y0aIAlWEBHSIZ+pmSj0U3AAU0RhUSrCfMJVaRozQpcbn/NCXCRl6Mzo7WjuOSxq0I4LLk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734406441; c=relaxed/simple; bh=8pUWEFVcCiSKKBLQq3/HQqfr7CrkLgpwoKUZOGEhZLY=; h=From:To:Cc:Subject:Date:Message-Id; b=CWHFmN4Vusdp95GhuUDC9FlS9smRiw7RD2e2ARHeMBpx3AuKyLoVdNPT93dnYMjyS6P4PCLWISk/5FcKO3yVTGvKAR6LLXakvjRTvIt9yyhun9QNr+xvKEU2DmI8VXsKV4CF1HpQ+9olOBBwz8iRxNZk07IY4+Mf21Twru/LcDs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=126.com; spf=pass smtp.mailfrom=126.com; dkim=pass (1024-bit key) header.d=126.com header.i=@126.com header.b=J8ZKi2nu; arc=none smtp.client-ip=220.197.31.7 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=126.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=126.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=126.com header.i=@126.com header.b="J8ZKi2nu" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=126.com; s=s110527; h=From:Subject:Date:Message-Id; bh=EFyBEGnfljxFoLLjFi /f//r0dupDm0Da3QllS1XtR1w=; b=J8ZKi2nuFusZKXVcqbmE5e5JjhwFt7fQUX sf0b1CyecUffRAaLCWnWjW6XKbE7gkGrfNfEb9s7bWT0iIMe8IjLt41tSrJx0qQd bNf7swFuRLlEDrmhJBJJxwkEXhDwUAbo5pqcniJWs2fEB8ezpfdsjWHiyRA41tgI QUVVMITjw= Received: from hg-OptiPlex-7040.hygon.cn (unknown []) by gzga-smtp-mtada-g1-0 (Coremail) with SMTP id _____wDnL4EH8WBnR6RmAQ--.28907S2; Tue, 17 Dec 2024 11:33:28 +0800 (CST) From: yangge1116@126.com To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, 21cnbao@gmail.com, david@redhat.com, baolin.wang@linux.alibaba.com, vbabka@suse.cz, liuzixing@hygon.cn, yangge Subject: [PATCH V6] mm, compaction: don't use ALLOC_CMA in long term GUP flow Date: Tue, 17 Dec 2024 11:33:25 +0800 Message-Id: <1734406405-25847-1-git-send-email-yangge1116@126.com> X-Mailer: git-send-email 2.7.4 X-CM-TRANSID: _____wDnL4EH8WBnR6RmAQ--.28907S2 X-Coremail-Antispam: 1Uf129KBjvJXoW3Cr4rCFyxGr4fuFy7Kry5twb_yoWkAr47pF 48Za4Iy3yrX3W3GFW8tF4vvF1Yqr4xGF48AryIgw18Zw13KF9F9as7KFy7AFWrWr98AFWY vFWqkrZ7GFsxAaDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0zKsj8bUUUUU= X-CM-SenderInfo: 51dqwwjhrrila6rslhhfrp/1tbiWQa4G2dg7B5gBwAAsu Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: yangge Since commit 984fdba6a32e ("mm, compaction: use proper alloc_flags in __compaction_suitable()") allow compaction to proceed when free pages required for compaction reside in the CMA pageblocks, it's possible that __compaction_suitable() always returns true, and in some cases, it's not acceptable. There are 4 NUMA nodes on my machine, and each NUMA node has 32GB of memory. I have configured 16GB of CMA memory on each NUMA node, and starting a 32GB virtual machine with device passthrough is extremely slow, taking almost an hour. During the start-up of the virtual machine, it will call pin_user_pages_remote(..., FOLL_LONGTERM, ...) to allocate memory. Long term GUP cannot allocate memory from CMA area, so a maximum of 16 GB of no-CMA memory on a NUMA node can be used as virtual machine memory. Since there is 16G of free CMA memory on the NUMA node, watermark for order-0 always be met for compaction, so __compaction_suitable() always returns true, even if the node is unable to allocate non-CMA memory for the virtual machine. For costly allocations, because __compaction_suitable() always returns true, __alloc_pages_slowpath() can't exit at the appropriate place, resulting in excessively long virtual machine startup times. Call trace: __alloc_pages_slowpath if (compact_result =3D=3D COMPACT_SKIPPED || compact_result =3D=3D COMPACT_DEFERRED) goto nopage; // should exit __alloc_pages_slowpath() from here In order to quickly fall back to remote node, we should remove ALLOC_CMA both in __compaction_suitable() and __isolate_free_page() in long term GUP flow. After this fix, starting a 32GB virtual machine with device passthrough takes only a few seconds. Fixes: 984fdba6a32e ("mm, compaction: use proper alloc_flags in __compactio= n_suitable()") Cc: Signed-off-by: yangge Reviewed-by: Baolin Wang --- V6: -- update cc->alloc_flags to keep the original loginc V5: - add 'alloc_flags' parameter for __isolate_free_page() - remove 'usa_cma' variable V4: - rich the commit log description V3: - fix build errors - add ALLOC_CMA both in should_continue_reclaim() and compaction_ready() V2: - using the 'cc->alloc_flags' to determin if 'ALLOC_CMA' is needed - rich the commit log description include/linux/compaction.h | 6 ++++-- mm/compaction.c | 26 +++++++++++++++----------- mm/internal.h | 3 ++- mm/page_alloc.c | 7 +++++-- mm/page_isolation.c | 3 ++- mm/page_reporting.c | 2 +- mm/vmscan.c | 4 ++-- 7 files changed, 31 insertions(+), 20 deletions(-) diff --git a/include/linux/compaction.h b/include/linux/compaction.h index e947764..b4c3ac3 100644 --- a/include/linux/compaction.h +++ b/include/linux/compaction.h @@ -90,7 +90,8 @@ extern enum compact_result try_to_compact_pages(gfp_t gfp= _mask, struct page **page); extern void reset_isolation_suitable(pg_data_t *pgdat); extern bool compaction_suitable(struct zone *zone, int order, - int highest_zoneidx); + int highest_zoneidx, + unsigned int alloc_flags); =20 extern void compaction_defer_reset(struct zone *zone, int order, bool alloc_success); @@ -108,7 +109,8 @@ static inline void reset_isolation_suitable(pg_data_t *= pgdat) } =20 static inline bool compaction_suitable(struct zone *zone, int order, - int highest_zoneidx) + int highest_zoneidx, + unsigned int alloc_flags) { return false; } diff --git a/mm/compaction.c b/mm/compaction.c index 07bd227..d92ba6c 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -655,7 +655,7 @@ static unsigned long isolate_freepages_block(struct com= pact_control *cc, =20 /* Found a free page, will break it into order-0 pages */ order =3D buddy_order(page); - isolated =3D __isolate_free_page(page, order); + isolated =3D __isolate_free_page(page, order, cc->alloc_flags); if (!isolated) break; set_page_private(page, order); @@ -1634,7 +1634,7 @@ static void fast_isolate_freepages(struct compact_con= trol *cc) =20 /* Isolate the page if available */ if (page) { - if (__isolate_free_page(page, order)) { + if (__isolate_free_page(page, order, cc->alloc_flags)) { set_page_private(page, order); nr_isolated =3D 1 << order; nr_scanned +=3D nr_isolated - 1; @@ -2381,6 +2381,7 @@ static enum compact_result compact_finished(struct co= mpact_control *cc) =20 static bool __compaction_suitable(struct zone *zone, int order, int highest_zoneidx, + unsigned int alloc_flags, unsigned long wmark_target) { unsigned long watermark; @@ -2395,25 +2396,26 @@ static bool __compaction_suitable(struct zone *zone= , int order, * even if compaction succeeds. * For costly orders, we require low watermark instead of min for * compaction to proceed to increase its chances. - * ALLOC_CMA is used, as pages in CMA pageblocks are considered - * suitable migration targets + * In addition to long term GUP flow, ALLOC_CMA is used, as pages in + * CMA pageblocks are considered suitable migration targets */ watermark =3D (order > PAGE_ALLOC_COSTLY_ORDER) ? low_wmark_pages(zone) : min_wmark_pages(zone); watermark +=3D compact_gap(order); return __zone_watermark_ok(zone, 0, watermark, highest_zoneidx, - ALLOC_CMA, wmark_target); + alloc_flags & ALLOC_CMA, wmark_target); } =20 /* * compaction_suitable: Is this suitable to run compaction on this zone no= w? */ -bool compaction_suitable(struct zone *zone, int order, int highest_zoneidx) +bool compaction_suitable(struct zone *zone, int order, int highest_zoneidx, + unsigned int alloc_flags) { enum compact_result compact_result; bool suitable; =20 - suitable =3D __compaction_suitable(zone, order, highest_zoneidx, + suitable =3D __compaction_suitable(zone, order, highest_zoneidx, alloc_fl= ags, zone_page_state(zone, NR_FREE_PAGES)); /* * fragmentation index determines if allocation failures are due to @@ -2474,7 +2476,7 @@ bool compaction_zonelist_suitable(struct alloc_contex= t *ac, int order, available =3D zone_reclaimable_pages(zone) / order; available +=3D zone_page_state_snapshot(zone, NR_FREE_PAGES); if (__compaction_suitable(zone, order, ac->highest_zoneidx, - available)) + alloc_flags, available)) return true; } =20 @@ -2499,7 +2501,7 @@ compaction_suit_allocation_order(struct zone *zone, u= nsigned int order, alloc_flags)) return COMPACT_SUCCESS; =20 - if (!compaction_suitable(zone, order, highest_zoneidx)) + if (!compaction_suitable(zone, order, highest_zoneidx, alloc_flags)) return COMPACT_SKIPPED; =20 return COMPACT_CONTINUE; @@ -2893,6 +2895,7 @@ static int compact_node(pg_data_t *pgdat, bool proact= ive) struct compact_control cc =3D { .order =3D -1, .mode =3D proactive ? MIGRATE_SYNC_LIGHT : MIGRATE_SYNC, + .alloc_flags =3D ALLOC_CMA, .ignore_skip_hint =3D true, .whole_zone =3D true, .gfp_mask =3D GFP_KERNEL, @@ -3037,7 +3040,7 @@ static bool kcompactd_node_suitable(pg_data_t *pgdat) =20 ret =3D compaction_suit_allocation_order(zone, pgdat->kcompactd_max_order, - highest_zoneidx, ALLOC_WMARK_MIN); + highest_zoneidx, ALLOC_CMA | ALLOC_WMARK_MIN); if (ret =3D=3D COMPACT_CONTINUE) return true; } @@ -3058,6 +3061,7 @@ static void kcompactd_do_work(pg_data_t *pgdat) .search_order =3D pgdat->kcompactd_max_order, .highest_zoneidx =3D pgdat->kcompactd_highest_zoneidx, .mode =3D MIGRATE_SYNC_LIGHT, + .alloc_flags =3D ALLOC_CMA | ALLOC_WMARK_MIN, .ignore_skip_hint =3D false, .gfp_mask =3D GFP_KERNEL, }; @@ -3078,7 +3082,7 @@ static void kcompactd_do_work(pg_data_t *pgdat) continue; =20 ret =3D compaction_suit_allocation_order(zone, - cc.order, zoneid, ALLOC_WMARK_MIN); + cc.order, zoneid, cc.alloc_flags); if (ret !=3D COMPACT_CONTINUE) continue; =20 diff --git a/mm/internal.h b/mm/internal.h index 3922788..6d257c8 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -662,7 +662,8 @@ static inline void clear_zone_contiguous(struct zone *z= one) zone->contiguous =3D false; } =20 -extern int __isolate_free_page(struct page *page, unsigned int order); +extern int __isolate_free_page(struct page *page, unsigned int order, + unsigned int alloc_flags); extern void __putback_isolated_page(struct page *page, unsigned int order, int mt); extern void memblock_free_pages(struct page *page, unsigned long pfn, diff --git a/mm/page_alloc.c b/mm/page_alloc.c index dde19db..1bfdca3 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2809,7 +2809,8 @@ void split_page(struct page *page, unsigned int order) } EXPORT_SYMBOL_GPL(split_page); =20 -int __isolate_free_page(struct page *page, unsigned int order) +int __isolate_free_page(struct page *page, unsigned int order, + unsigned int alloc_flags) { struct zone *zone =3D page_zone(page); int mt =3D get_pageblock_migratetype(page); @@ -2823,7 +2824,8 @@ int __isolate_free_page(struct page *page, unsigned i= nt order) * exists. */ watermark =3D zone->_watermark[WMARK_MIN] + (1UL << order); - if (!zone_watermark_ok(zone, 0, watermark, 0, ALLOC_CMA)) + if (!zone_watermark_ok(zone, 0, watermark, 0, + alloc_flags & ALLOC_CMA)) return 0; } =20 @@ -6454,6 +6456,7 @@ int alloc_contig_range_noprof(unsigned long start, un= signed long end, .order =3D -1, .zone =3D page_zone(pfn_to_page(start)), .mode =3D MIGRATE_SYNC, + .alloc_flags =3D ALLOC_CMA, .ignore_skip_hint =3D true, .no_set_skip_hint =3D true, .alloc_contig =3D true, diff --git a/mm/page_isolation.c b/mm/page_isolation.c index c608e9d..a1f2c79 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -229,7 +229,8 @@ static void unset_migratetype_isolate(struct page *page= , int migratetype) buddy =3D find_buddy_page_pfn(page, page_to_pfn(page), order, NULL); if (buddy && !is_migrate_isolate_page(buddy)) { - isolated_page =3D !!__isolate_free_page(page, order); + isolated_page =3D !!__isolate_free_page(page, order, + ALLOC_CMA); /* * Isolating a free page in an isolated pageblock * is expected to always work as watermarks don't diff --git a/mm/page_reporting.c b/mm/page_reporting.c index e4c428e..fd3813b 100644 --- a/mm/page_reporting.c +++ b/mm/page_reporting.c @@ -198,7 +198,7 @@ page_reporting_cycle(struct page_reporting_dev_info *pr= dev, struct zone *zone, =20 /* Attempt to pull page from list and place in scatterlist */ if (*offset) { - if (!__isolate_free_page(page, order)) { + if (!__isolate_free_page(page, order, ALLOC_CMA)) { next =3D page; break; } diff --git a/mm/vmscan.c b/mm/vmscan.c index 5e03a61..33f5b46 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -5815,7 +5815,7 @@ static inline bool should_continue_reclaim(struct pgl= ist_data *pgdat, sc->reclaim_idx, 0)) return false; =20 - if (compaction_suitable(zone, sc->order, sc->reclaim_idx)) + if (compaction_suitable(zone, sc->order, sc->reclaim_idx, ALLOC_CMA)) return false; } =20 @@ -6043,7 +6043,7 @@ static inline bool compaction_ready(struct zone *zone= , struct scan_control *sc) return true; =20 /* Compaction cannot yet proceed. Do reclaim. */ - if (!compaction_suitable(zone, sc->order, sc->reclaim_idx)) + if (!compaction_suitable(zone, sc->order, sc->reclaim_idx, ALLOC_CMA)) return false; =20 /* --=20 2.7.4