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Sat, 14 Dec 2024 14:23:43 +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 V2] mm, compaction: don't use ALLOC_CMA in long term GUP flow Date: Sat, 14 Dec 2024 14:23:40 +0800 Message-Id: <1734157420-31110-1-git-send-email-yangge1116@126.com> X-Mailer: git-send-email 2.7.4 X-CM-TRANSID: qSkvCgDnr_NuJF1n7VZTCQ--.7274S2 X-Coremail-Antispam: 1Uf129KBjvJXoWxtry8Zr4kJrWUGr4xXr4fKrg_yoWxuF13pF 18ZasFyws5XF13Gr48tF409a15tw4xGF18JryIgw1xZw1akFn2v3WkKFy7AF15XryayF4Y qFWq9ryDGFsxAaDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0zNLvKwUUUUU= X-Originating-IP: [118.242.3.34] X-CM-SenderInfo: 51dqwwjhrrila6rslhhfrp/1tbifgq1G2ddD3K5DQAAsp X-Rspamd-Server: rspam05 X-Stat-Signature: 43z8ot78x9i9j9agqc5j8xhpx7bhycpm X-Rspamd-Queue-Id: 5472C180007 X-Rspam-User: X-HE-Tag: 1734157437-570139 X-HE-Meta: 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 /G1LBPz0 OlbJVwzIRdlL+k08DaoK3Cw/M+v2KBkcFRdFvTL2LeWRlEuxYsa+bcASG82AGPWVWN6f6ZG4m2b+B6SoJYj1xXKkPZhtDNjgFA8s2O28Ht4JEeGBetc4Nvlhb1x4mIl/1wrx/ts42DeQjpJBTg15Uv57Q8Hnj2cFm90SUm+SptvSm+03h/u02F1v5INj5taIqwBVj0FpoLVryDTfLBDB8TQ+3TeX3KZlczMnilyVZcj8SFFvqrbmvOAxdb3n/Ad77ae5Qq46V/Dmn77JsngV3sA5CwR9n97FxEUyjxm4ncCfANN9QZS3lrQPXRJf2VGXlaqdZ7uTH8q400qBStNuiZERBPLDXgLGTQzXgt19C76CuZ03nP1ms+dvyOzioDWqMGAiuYL7KXzqdj10= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 == COMPACT_SKIPPED || compact_result == 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 __compaction_suitable()") Cc: Signed-off-by: yangge --- V2: - using the 'cc->alloc_flags' to determin if 'ALLOC_CMA' is needed - rich the commit log description include/linux/compaction.h | 3 ++- mm/compaction.c | 18 +++++++++++------- mm/page_alloc.c | 4 +++- mm/vmscan.c | 4 ++-- 4 files changed, 18 insertions(+), 11 deletions(-) diff --git a/include/linux/compaction.h b/include/linux/compaction.h index e947764..0c6f97a 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); extern void compaction_defer_reset(struct zone *zone, int order, bool alloc_success); diff --git a/mm/compaction.c b/mm/compaction.c index 07bd227..585f5ab 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -2381,9 +2381,11 @@ static enum compact_result compact_finished(struct compact_control *cc) static bool __compaction_suitable(struct zone *zone, int order, int highest_zoneidx, + unsigned int alloc_flags, unsigned long wmark_target) { unsigned long watermark; + bool use_cma; /* * Watermarks for order-0 must be met for compaction to be able to * isolate free pages for migration targets. This means that the @@ -2395,25 +2397,27 @@ 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 = (order > PAGE_ALLOC_COSTLY_ORDER) ? low_wmark_pages(zone) : min_wmark_pages(zone); watermark += compact_gap(order); + use_cma = !!(alloc_flags & ALLOC_CMA); return __zone_watermark_ok(zone, 0, watermark, highest_zoneidx, - ALLOC_CMA, wmark_target); + use_cma ? ALLOC_CMA : 0, wmark_target); } /* * compaction_suitable: Is this suitable to run compaction on this zone now? */ -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; - suitable = __compaction_suitable(zone, order, highest_zoneidx, + suitable = __compaction_suitable(zone, order, highest_zoneidx, alloc_flags, zone_page_state(zone, NR_FREE_PAGES)); /* * fragmentation index determines if allocation failures are due to @@ -2474,7 +2478,7 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order, available = zone_reclaimable_pages(zone) / order; available += zone_page_state_snapshot(zone, NR_FREE_PAGES); if (__compaction_suitable(zone, order, ac->highest_zoneidx, - available)) + alloc_flags, available)) return true; } @@ -2499,7 +2503,7 @@ compaction_suit_allocation_order(struct zone *zone, unsigned int order, alloc_flags)) return COMPACT_SUCCESS; - if (!compaction_suitable(zone, order, highest_zoneidx)) + if (!compaction_suitable(zone, order, highest_zoneidx, alloc_flags)) return COMPACT_SKIPPED; return COMPACT_CONTINUE; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index dde19db..9a5dfda 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2813,6 +2813,7 @@ int __isolate_free_page(struct page *page, unsigned int order) { struct zone *zone = page_zone(page); int mt = get_pageblock_migratetype(page); + bool pin; if (!is_migrate_isolate(mt)) { unsigned long watermark; @@ -2823,7 +2824,8 @@ int __isolate_free_page(struct page *page, unsigned int order) * exists. */ watermark = zone->_watermark[WMARK_MIN] + (1UL << order); - if (!zone_watermark_ok(zone, 0, watermark, 0, ALLOC_CMA)) + pin = !!(current->flags & PF_MEMALLOC_PIN); + if (!zone_watermark_ok(zone, 0, watermark, 0, pin ? 0 : ALLOC_CMA)) return 0; } diff --git a/mm/vmscan.c b/mm/vmscan.c index 5e03a61..806f031 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -5815,7 +5815,7 @@ static inline bool should_continue_reclaim(struct pglist_data *pgdat, sc->reclaim_idx, 0)) return false; - if (compaction_suitable(zone, sc->order, sc->reclaim_idx)) + if (compaction_suitable(zone, sc->order, sc->reclaim_idx, 0)) return false; } @@ -6043,7 +6043,7 @@ static inline bool compaction_ready(struct zone *zone, struct scan_control *sc) return true; /* Compaction cannot yet proceed. Do reclaim. */ - if (!compaction_suitable(zone, sc->order, sc->reclaim_idx)) + if (!compaction_suitable(zone, sc->order, sc->reclaim_idx, 0)) return false; /*