From nobody Wed Dec 17 19:51:02 2025 Received: from m16.mail.126.com (m16.mail.126.com [220.197.31.9]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 071B9204088; Mon, 16 Dec 2024 11:55:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.9 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734350147; cv=none; b=g6zs/GvC6iO5M5PpJIxd/P1tgWlwg/RkPPN7cHwp6sBR2/M616AwDFfCYl0IlzOXJR5dJBkUyeR+kmjtu24Qb3JvMxlCInJUtejRUzfeHyhRbyx5FCwjjqmNj8h/mmW19BdC4lptN3uvvQ0HQ7k5WroAcwO/khm/MztEqzcFqyo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734350147; c=relaxed/simple; bh=G5tUMqKyP1F13z/KdIHU03qX75lbfqEpYVMS8+8jhsY=; h=From:To:Cc:Subject:Date:Message-Id; b=YHxRCL5yFU8EI3LN2KdkGNS/dgd4eCt4+MJkcBjQZEh7XF3WJVEJ3E3fh5l0EvX10QesQgMr6UODrqoLIIrJpoit0fICkrcQDItbfqSx2dVgr7GzDRNmDJoEfHIIfOHld8Yl/VzOtz0YwNjxJjSmazGXpd7Jk84MCu6JcjQO6WQ= 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=loZNMNdq; arc=none smtp.client-ip=220.197.31.9 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="loZNMNdq" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=126.com; s=s110527; h=From:Subject:Date:Message-Id; bh=UKrvP/Ymp5jq0pAVdR g5jcH+ViqV5yReScKB+YOXh1Q=; b=loZNMNdqCCuwB8aZY3ZLIRV3eaFrX5LFHK lem8vfSFUYH/sSj/nVGDOzzRP1zkBPKbcbEXOxMGXVhZ/dzLgZYrjsrYd0c4jccv f8HpYsMn9TP0Qc6nGUBmfHX6CwolVv5+OhkgWqBF2IzwU4QnryrR2++PP3qg2zxX 92s1wQHOs= Received: from hg-OptiPlex-7040.hygon.cn (unknown []) by gzga-smtp-mtada-g0-2 (Coremail) with SMTP id _____wDHjwjdFGBnGCMaAg--.3044S2; Mon, 16 Dec 2024 19:54:06 +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 V5] mm, compaction: don't use ALLOC_CMA in long term GUP flow Date: Mon, 16 Dec 2024 19:54:04 +0800 Message-Id: <1734350044-12928-1-git-send-email-yangge1116@126.com> X-Mailer: git-send-email 2.7.4 X-CM-TRANSID: _____wDHjwjdFGBnGCMaAg--.3044S2 X-Coremail-Antispam: 1Uf129KBjvJXoWxtry8Zr4kJrWUGr4xCr1kuFg_yoWDGr18pF 48X3WIy3yrX3W3CrW8JF4vv3WYqw4xGF48AryIgw18Zw13KF92v3Z7KFy7AFy5Wr95AFWY vFWqkrWkGFsxAaDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0zKsj8bUUUUU= X-CM-SenderInfo: 51dqwwjhrrila6rslhhfrp/1tbiOgW3G2dgFFkEhwABsb 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 --- 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 | 20 +++++++++++--------- mm/internal.h | 3 ++- mm/page_alloc.c | 6 ++++-- mm/page_isolation.c | 3 ++- mm/page_reporting.c | 2 +- mm/vmscan.c | 4 ++-- 7 files changed, 26 insertions(+), 18 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..b10d921 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; 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..ecb2fd7 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 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