diff options
Diffstat (limited to 'mm/page_alloc.c')
| -rw-r--r-- | mm/page_alloc.c | 217 |
1 files changed, 200 insertions, 17 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 94917c729120..e3ea5bf5c459 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -88,6 +88,9 @@ typedef int __bitwise fpi_t; */ #define FPI_TO_TAIL ((__force fpi_t)BIT(1)) +/* Free the page without taking locks. Rely on trylock only. */ +#define FPI_TRYLOCK ((__force fpi_t)BIT(2)) + /* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */ static DEFINE_MUTEX(pcp_batch_high_lock); #define MIN_PERCPU_PAGELIST_HIGH_FRACTION (8) @@ -1249,13 +1252,44 @@ static void split_large_buddy(struct zone *zone, struct page *page, } while (1); } +static void add_page_to_zone_llist(struct zone *zone, struct page *page, + unsigned int order) +{ + /* Remember the order */ + page->order = order; + /* Add the page to the free list */ + llist_add(&page->pcp_llist, &zone->trylock_free_pages); +} + static void free_one_page(struct zone *zone, struct page *page, unsigned long pfn, unsigned int order, fpi_t fpi_flags) { + struct llist_head *llhead; unsigned long flags; - spin_lock_irqsave(&zone->lock, flags); + if (!spin_trylock_irqsave(&zone->lock, flags)) { + if (unlikely(fpi_flags & FPI_TRYLOCK)) { + add_page_to_zone_llist(zone, page, order); + return; + } + spin_lock_irqsave(&zone->lock, flags); + } + + /* The lock succeeded. Process deferred pages. */ + llhead = &zone->trylock_free_pages; + if (unlikely(!llist_empty(llhead) && !(fpi_flags & FPI_TRYLOCK))) { + struct llist_node *llnode; + struct page *p, *tmp; + + llnode = llist_del_all(llhead); + llist_for_each_entry_safe(p, tmp, llnode, pcp_llist) { + unsigned int p_order = p->order; + + split_large_buddy(zone, p, page_to_pfn(p), p_order, fpi_flags); + __count_vm_events(PGFREE, 1 << p_order); + } + } split_large_buddy(zone, page, pfn, order, fpi_flags); spin_unlock_irqrestore(&zone->lock, flags); @@ -2307,7 +2341,11 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order, unsigned long flags; int i; - spin_lock_irqsave(&zone->lock, flags); + if (!spin_trylock_irqsave(&zone->lock, flags)) { + if (unlikely(alloc_flags & ALLOC_TRYLOCK)) + return 0; + spin_lock_irqsave(&zone->lock, flags); + } for (i = 0; i < count; ++i) { struct page *page = __rmqueue(zone, order, migratetype, alloc_flags); @@ -2595,7 +2633,7 @@ static int nr_pcp_high(struct per_cpu_pages *pcp, struct zone *zone, static void free_frozen_page_commit(struct zone *zone, struct per_cpu_pages *pcp, struct page *page, int migratetype, - unsigned int order) + unsigned int order, fpi_t fpi_flags) { int high, batch; int pindex; @@ -2630,6 +2668,14 @@ static void free_frozen_page_commit(struct zone *zone, } if (pcp->free_count < (batch << CONFIG_PCP_BATCH_SCALE_MAX)) pcp->free_count += (1 << order); + + if (unlikely(fpi_flags & FPI_TRYLOCK)) { + /* + * Do not attempt to take a zone lock. Let pcp->count get + * over high mark temporarily. + */ + return; + } high = nr_pcp_high(pcp, zone, batch, free_high); if (pcp->count >= high) { free_pcppages_bulk(zone, nr_pcp_free(pcp, batch, high, free_high), @@ -2644,7 +2690,8 @@ static void free_frozen_page_commit(struct zone *zone, /* * Free a pcp page */ -void free_frozen_pages(struct page *page, unsigned int order) +static void __free_frozen_pages(struct page *page, unsigned int order, + fpi_t fpi_flags) { unsigned long __maybe_unused UP_flags; struct per_cpu_pages *pcp; @@ -2653,7 +2700,7 @@ void free_frozen_pages(struct page *page, unsigned int order) int migratetype; if (!pcp_allowed_order(order)) { - __free_pages_ok(page, order, FPI_NONE); + __free_pages_ok(page, order, fpi_flags); return; } @@ -2671,23 +2718,33 @@ void free_frozen_pages(struct page *page, unsigned int order) migratetype = get_pfnblock_migratetype(page, pfn); if (unlikely(migratetype >= MIGRATE_PCPTYPES)) { if (unlikely(is_migrate_isolate(migratetype))) { - free_one_page(zone, page, pfn, order, FPI_NONE); + free_one_page(zone, page, pfn, order, fpi_flags); return; } migratetype = MIGRATE_MOVABLE; } + if (unlikely((fpi_flags & FPI_TRYLOCK) && IS_ENABLED(CONFIG_PREEMPT_RT) + && (in_nmi() || in_hardirq()))) { + add_page_to_zone_llist(zone, page, order); + return; + } pcp_trylock_prepare(UP_flags); pcp = pcp_spin_trylock(zone->per_cpu_pageset); if (pcp) { - free_frozen_page_commit(zone, pcp, page, migratetype, order); + free_frozen_page_commit(zone, pcp, page, migratetype, order, fpi_flags); pcp_spin_unlock(pcp); } else { - free_one_page(zone, page, pfn, order, FPI_NONE); + free_one_page(zone, page, pfn, order, fpi_flags); } pcp_trylock_finish(UP_flags); } +void free_frozen_pages(struct page *page, unsigned int order) +{ + __free_frozen_pages(page, order, FPI_NONE); +} + /* * Free a batch of folios */ @@ -2776,7 +2833,7 @@ void free_unref_folios(struct folio_batch *folios) trace_mm_page_free_batched(&folio->page); free_frozen_page_commit(zone, pcp, &folio->page, migratetype, - order); + order, FPI_NONE); } if (pcp) { @@ -2907,7 +2964,11 @@ struct page *rmqueue_buddy(struct zone *preferred_zone, struct zone *zone, do { page = NULL; - spin_lock_irqsave(&zone->lock, flags); + if (!spin_trylock_irqsave(&zone->lock, flags)) { + if (unlikely(alloc_flags & ALLOC_TRYLOCK)) + return NULL; + spin_lock_irqsave(&zone->lock, flags); + } if (alloc_flags & ALLOC_HIGHATOMIC) page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC); if (!page) { @@ -4512,7 +4573,12 @@ static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order, might_alloc(gfp_mask); - if (should_fail_alloc_page(gfp_mask, order)) + /* + * Don't invoke should_fail logic, since it may call + * get_random_u32() and printk() which need to spin_lock. + */ + if (!(*alloc_flags & ALLOC_TRYLOCK) && + should_fail_alloc_page(gfp_mask, order)) return false; *alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, *alloc_flags); @@ -4810,9 +4876,10 @@ unsigned long get_zeroed_page_noprof(gfp_t gfp_mask) EXPORT_SYMBOL(get_zeroed_page_noprof); /** - * __free_pages - Free pages allocated with alloc_pages(). + * ___free_pages - Free pages allocated with alloc_pages(). * @page: The page pointer returned from alloc_pages(). * @order: The order of the allocation. + * @fpi_flags: Free Page Internal flags. * * This function can free multi-page allocations that are not compound * pages. It does not check that the @order passed in matches that of @@ -4829,22 +4896,37 @@ EXPORT_SYMBOL(get_zeroed_page_noprof); * Context: May be called in interrupt context or while holding a normal * spinlock, but not in NMI context or while holding a raw spinlock. */ -void __free_pages(struct page *page, unsigned int order) +static void ___free_pages(struct page *page, unsigned int order, + fpi_t fpi_flags) { /* get PageHead before we drop reference */ int head = PageHead(page); struct alloc_tag *tag = pgalloc_tag_get(page); if (put_page_testzero(page)) - free_frozen_pages(page, order); + __free_frozen_pages(page, order, fpi_flags); else if (!head) { pgalloc_tag_sub_pages(tag, (1 << order) - 1); while (order-- > 0) - free_frozen_pages(page + (1 << order), order); + __free_frozen_pages(page + (1 << order), order, + fpi_flags); } } +void __free_pages(struct page *page, unsigned int order) +{ + ___free_pages(page, order, FPI_NONE); +} EXPORT_SYMBOL(__free_pages); +/* + * Can be called while holding raw_spin_lock or from IRQ and NMI for any + * page type (not only those that came from try_alloc_pages) + */ +void free_pages_nolock(struct page *page, unsigned int order) +{ + ___free_pages(page, order, FPI_TRYLOCK); +} + void free_pages(unsigned long addr, unsigned int order) { if (addr != 0) { @@ -7004,7 +7086,7 @@ static inline bool has_unaccepted_memory(void) static bool cond_accept_memory(struct zone *zone, unsigned int order) { - long to_accept; + long to_accept, wmark; bool ret = false; if (!has_unaccepted_memory()) @@ -7013,8 +7095,18 @@ static bool cond_accept_memory(struct zone *zone, unsigned int order) if (list_empty(&zone->unaccepted_pages)) return false; + wmark = promo_wmark_pages(zone); + + /* + * Watermarks have not been initialized yet. + * + * Accepting one MAX_ORDER page to ensure progress. + */ + if (!wmark) + return try_to_accept_memory_one(zone); + /* How much to accept to get to promo watermark? */ - to_accept = promo_wmark_pages(zone) - + to_accept = wmark - (zone_page_state(zone, NR_FREE_PAGES) - __zone_watermark_unusable_free(zone, order, 0) - zone_page_state(zone, NR_UNACCEPTED)); @@ -7071,3 +7163,94 @@ static bool __free_unaccepted(struct page *page) } #endif /* CONFIG_UNACCEPTED_MEMORY */ + +/** + * try_alloc_pages - opportunistic reentrant allocation from any context + * @nid: node to allocate from + * @order: allocation order size + * + * Allocates pages of a given order from the given node. This is safe to + * call from any context (from atomic, NMI, and also reentrant + * allocator -> tracepoint -> try_alloc_pages_noprof). + * Allocation is best effort and to be expected to fail easily so nobody should + * rely on the success. Failures are not reported via warn_alloc(). + * See always fail conditions below. + * + * Return: allocated page or NULL on failure. + */ +struct page *try_alloc_pages_noprof(int nid, unsigned int order) +{ + /* + * Do not specify __GFP_DIRECT_RECLAIM, since direct claim is not allowed. + * Do not specify __GFP_KSWAPD_RECLAIM either, since wake up of kswapd + * is not safe in arbitrary context. + * + * These two are the conditions for gfpflags_allow_spinning() being true. + * + * Specify __GFP_NOWARN since failing try_alloc_pages() is not a reason + * to warn. Also warn would trigger printk() which is unsafe from + * various contexts. We cannot use printk_deferred_enter() to mitigate, + * since the running context is unknown. + * + * Specify __GFP_ZERO to make sure that call to kmsan_alloc_page() below + * is safe in any context. Also zeroing the page is mandatory for + * BPF use cases. + * + * Though __GFP_NOMEMALLOC is not checked in the code path below, + * specify it here to highlight that try_alloc_pages() + * doesn't want to deplete reserves. + */ + gfp_t alloc_gfp = __GFP_NOWARN | __GFP_ZERO | __GFP_NOMEMALLOC + | __GFP_ACCOUNT; + unsigned int alloc_flags = ALLOC_TRYLOCK; + struct alloc_context ac = { }; + struct page *page; + + /* + * In PREEMPT_RT spin_trylock() will call raw_spin_lock() which is + * unsafe in NMI. If spin_trylock() is called from hard IRQ the current + * task may be waiting for one rt_spin_lock, but rt_spin_trylock() will + * mark the task as the owner of another rt_spin_lock which will + * confuse PI logic, so return immediately if called form hard IRQ or + * NMI. + * + * Note, irqs_disabled() case is ok. This function can be called + * from raw_spin_lock_irqsave region. + */ + if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq())) + return NULL; + if (!pcp_allowed_order(order)) + return NULL; + +#ifdef CONFIG_UNACCEPTED_MEMORY + /* Bailout, since try_to_accept_memory_one() needs to take a lock */ + if (has_unaccepted_memory()) + return NULL; +#endif + /* Bailout, since _deferred_grow_zone() needs to take a lock */ + if (deferred_pages_enabled()) + return NULL; + + if (nid == NUMA_NO_NODE) + nid = numa_node_id(); + + prepare_alloc_pages(alloc_gfp, order, nid, NULL, &ac, + &alloc_gfp, &alloc_flags); + + /* + * Best effort allocation from percpu free list. + * If it's empty attempt to spin_trylock zone->lock. + */ + page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac); + + /* Unlike regular alloc_pages() there is no __alloc_pages_slowpath(). */ + + if (memcg_kmem_online() && page && + unlikely(__memcg_kmem_charge_page(page, alloc_gfp, order) != 0)) { + free_pages_nolock(page, order); + page = NULL; + } + trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype); + kmsan_alloc_page(page, order, alloc_gfp); + return page; +} |