From 5ecf68877ed7ff4c7a96464b82eb84cc34d6d3f3 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Mon, 7 Dec 2020 09:36:14 +0100 Subject: [PATCH 2/2] xen: don't use page->lru for ZONE_DEVICE memory Commit 9e2369c06c8a18 ("xen: add helpers to allocate unpopulated memory") introduced usage of ZONE_DEVICE memory for foreign memory mappings. Unfortunately this collides with using page->lru for Xen backend private page caches. Fix that by using page->zone_device_data instead. Fixes: 9e2369c06c8a18 ("xen: add helpers to allocate unpopulated memory") Signed-off-by: Juergen Gross --- drivers/xen/grant-table.c | 65 +++++++++++++++++++++++++++++---- drivers/xen/unpopulated-alloc.c | 20 +++++----- include/xen/grant_table.h | 4 ++ 3 files changed, 73 insertions(+), 16 deletions(-) diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c index e2e42912f241..ddb38a3d7680 100644 --- a/drivers/xen/grant-table.c +++ b/drivers/xen/grant-table.c @@ -813,10 +813,63 @@ int gnttab_alloc_pages(int nr_pages, struct page **pages) } EXPORT_SYMBOL_GPL(gnttab_alloc_pages); +#ifdef CONFIG_XEN_UNPOPULATED_ALLOC +static inline void cache_init(struct gnttab_page_cache *cache) +{ + cache->pages = NULL; +} + +static inline bool cache_empty(struct gnttab_page_cache *cache) +{ + return cache->pages; +} + +static inline struct page *cache_deq(struct gnttab_page_cache *cache) +{ + struct page *page; + + page = cache->pages; + cache->pages = page->zone_device_data; + + return page; +} + +static inline void cache_enq(struct gnttab_page_cache *cache, struct page *page) +{ + page->zone_device_data = cache->pages; + cache->pages = page; +} +#else +static inline void cache_init(struct gnttab_page_cache *cache) +{ + INIT_LIST_HEAD(&cache->pages); +} + +static inline bool cache_empty(struct gnttab_page_cache *cache) +{ + return list_empty(&cache->pages); +} + +static inline struct page *cache_deq(struct gnttab_page_cache *cache) +{ + struct page *page; + + page = list_first_entry(&cache->pages, struct page, lru); + list_del(&page[0]->lru); + + return page; +} + +static inline void cache_enq(struct gnttab_page_cache *cache, struct page *page) +{ + list_add(&page->lru, &cache->pages); +} +#endif + void gnttab_page_cache_init(struct gnttab_page_cache *cache) { spin_lock_init(&cache->lock); - INIT_LIST_HEAD(&cache->pages); + cache_init(cache); cache->num_pages = 0; } EXPORT_SYMBOL_GPL(gnttab_page_cache_init); @@ -827,13 +880,12 @@ int gnttab_page_cache_get(struct gnttab_page_cache *cache, struct page **page) spin_lock_irqsave(&cache->lock, flags); - if (list_empty(&cache->pages)) { + if (cache_empty(cache)) { spin_unlock_irqrestore(&cache->lock, flags); return gnttab_alloc_pages(1, page); } - page[0] = list_first_entry(&cache->pages, struct page, lru); - list_del(&page[0]->lru); + page[0] = cache_deq(cache); cache->num_pages--; spin_unlock_irqrestore(&cache->lock, flags); @@ -851,7 +903,7 @@ void gnttab_page_cache_put(struct gnttab_page_cache *cache, struct page **page, spin_lock_irqsave(&cache->lock, flags); for (i = 0; i < num; i++) - list_add(&page[i]->lru, &cache->pages); + cache_enq(cache, page[i]); cache->num_pages += num; spin_unlock_irqrestore(&cache->lock, flags); @@ -867,8 +919,7 @@ void gnttab_page_cache_shrink(struct gnttab_page_cache *cache, unsigned int num) spin_lock_irqsave(&cache->lock, flags); while (cache->num_pages > num) { - page[i] = list_first_entry(&cache->pages, struct page, lru); - list_del(&page[i]->lru); + page[i] = cache_deq(cache); cache->num_pages--; if (++i == ARRAY_SIZE(page)) { spin_unlock_irqrestore(&cache->lock, flags); diff --git a/drivers/xen/unpopulated-alloc.c b/drivers/xen/unpopulated-alloc.c index 8c512ea550bb..7762c1bb23cb 100644 --- a/drivers/xen/unpopulated-alloc.c +++ b/drivers/xen/unpopulated-alloc.c @@ -12,7 +12,7 @@ #include static DEFINE_MUTEX(list_lock); -static LIST_HEAD(page_list); +static struct page *page_list; static unsigned int list_count; static int fill_list(unsigned int nr_pages) @@ -84,7 +84,8 @@ static int fill_list(unsigned int nr_pages) struct page *pg = virt_to_page(vaddr + PAGE_SIZE * i); BUG_ON(!virt_addr_valid(vaddr + PAGE_SIZE * i)); - list_add(&pg->lru, &page_list); + pg->zone_device_data = page_list; + page_list = pg; list_count++; } @@ -118,12 +119,10 @@ int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages) } for (i = 0; i < nr_pages; i++) { - struct page *pg = list_first_entry_or_null(&page_list, - struct page, - lru); + struct page *pg = page_list; BUG_ON(!pg); - list_del(&pg->lru); + page_list = pg->zone_device_data; list_count--; pages[i] = pg; @@ -134,7 +133,8 @@ int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages) unsigned int j; for (j = 0; j <= i; j++) { - list_add(&pages[j]->lru, &page_list); + pages[j]->zone_device_data = page_list; + page_list = pages[j]; list_count++; } goto out; @@ -160,7 +160,8 @@ void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages) mutex_lock(&list_lock); for (i = 0; i < nr_pages; i++) { - list_add(&pages[i]->lru, &page_list); + pages[i]->zone_device_data = page_list; + page_list = pages[i]; list_count++; } mutex_unlock(&list_lock); @@ -189,7 +190,8 @@ static int __init init(void) struct page *pg = pfn_to_page(xen_extra_mem[i].start_pfn + j); - list_add(&pg->lru, &page_list); + pg->zone_device_data = page_list; + page_list = pg; list_count++; } } diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h index c6ef8ffc1a09..b9c937b3a149 100644 --- a/include/xen/grant_table.h +++ b/include/xen/grant_table.h @@ -200,7 +200,11 @@ void gnttab_free_pages(int nr_pages, struct page **pages); struct gnttab_page_cache { spinlock_t lock; +#ifdef CONFIG_XEN_UNPOPULATED_ALLOC + struct page *pages; +#else struct list_head pages; +#endif unsigned int num_pages; }; -- 2.26.2