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[208.91.0.190]) by mx.google.com with ESMTPS id a85si23305392pfj.12.2019.04.25.12.14.34 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 25 Apr 2019 12:14:34 -0700 (PDT) Received-SPF: pass (google.com: domain of namit@vmware.com designates 208.91.0.190 as permitted sender) client-ip=208.91.0.190; Authentication-Results: mx.google.com; spf=pass (google.com: domain of namit@vmware.com designates 208.91.0.190 as permitted sender) smtp.mailfrom=namit@vmware.com; dmarc=pass (p=QUARANTINE sp=NONE dis=NONE) header.from=vmware.com Received: from sc9-mailhost3.vmware.com (10.113.161.73) by EX13-EDG-OU-002.vmware.com (10.113.208.156) with Microsoft SMTP Server id 15.0.1156.6; Thu, 25 Apr 2019 12:14:31 -0700 Received: from sc2-haas01-esx0118.eng.vmware.com (sc2-haas01-esx0118.eng.vmware.com [10.172.44.118]) by sc9-mailhost3.vmware.com (Postfix) with ESMTP id 74328412D1; Thu, 25 Apr 2019 12:14:32 -0700 (PDT) From: Nadav Amit To: Greg Kroah-Hartman , "Michael S. Tsirkin" CC: Arnd Bergmann , Julien Freche , "VMware, Inc." , Jason Wang , , , , Nadav Amit Subject: [PATCH v4 4/4] vmw_balloon: Split refused pages Date: Thu, 25 Apr 2019 04:54:45 -0700 Message-ID: <20190425115445.20815-5-namit@vmware.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190425115445.20815-1-namit@vmware.com> References: <20190425115445.20815-1-namit@vmware.com> MIME-Version: 1.0 Content-Type: text/plain Received-SPF: None (EX13-EDG-OU-002.vmware.com: namit@vmware.com does not designate permitted sender hosts) 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: The hypervisor might refuse to inflate pages. While the balloon driver handles this scenario correctly, a refusal to inflate a 2MB pages might cause the same page to be allocated again later just for its inflation to be refused again. This wastes energy and time. To avoid this situation, split the 2MB page to 4KB pages, and then try to inflate each one individually. Most of the 4KB pages out of the 2MB should be inflated successfully, and the balloon is likely to prevent the scenario of repeated refused inflation. Reviewed-by: Xavier Deguillard Signed-off-by: Nadav Amit --- drivers/misc/vmw_balloon.c | 63 +++++++++++++++++++++++++++++++------- 1 file changed, 52 insertions(+), 11 deletions(-) diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c index 4b5e939ff4c8..043eed845246 100644 --- a/drivers/misc/vmw_balloon.c +++ b/drivers/misc/vmw_balloon.c @@ -239,6 +239,7 @@ static DEFINE_STATIC_KEY_FALSE(balloon_stat_enabled); struct vmballoon_ctl { struct list_head pages; struct list_head refused_pages; + struct list_head prealloc_pages; unsigned int n_refused_pages; unsigned int n_pages; enum vmballoon_page_size_type page_size; @@ -668,15 +669,25 @@ static int vmballoon_alloc_page_list(struct vmballoon *b, unsigned int i; for (i = 0; i < req_n_pages; i++) { - if (ctl->page_size == VMW_BALLOON_2M_PAGE) - page = alloc_pages(__GFP_HIGHMEM|__GFP_NOWARN| + /* + * First check if we happen to have pages that were allocated + * before. This happens when 2MB page rejected during inflation + * by the hypervisor, and then split into 4KB pages. + */ + if (!list_empty(&ctl->prealloc_pages)) { + page = list_first_entry(&ctl->prealloc_pages, + struct page, lru); + list_del(&page->lru); + } else { + if (ctl->page_size == VMW_BALLOON_2M_PAGE) + page = alloc_pages(__GFP_HIGHMEM|__GFP_NOWARN| __GFP_NOMEMALLOC, VMW_BALLOON_2M_ORDER); - else - page = balloon_page_alloc(); + else + page = balloon_page_alloc(); - /* Update statistics */ - vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC, - ctl->page_size); + vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC, + ctl->page_size); + } if (page) { vmballoon_mark_page_offline(page, ctl->page_size); @@ -922,7 +933,8 @@ static void vmballoon_release_page_list(struct list_head *page_list, __free_pages(page, vmballoon_page_order(page_size)); } - *n_pages = 0; + if (n_pages) + *n_pages = 0; } @@ -1054,6 +1066,32 @@ static void vmballoon_dequeue_page_list(struct vmballoon *b, *n_pages = i; } +/** + * vmballoon_split_refused_pages() - Split the 2MB refused pages to 4k. + * + * If inflation of 2MB pages was denied by the hypervisor, it is likely to be + * due to one or few 4KB pages. These 2MB pages may keep being allocated and + * then being refused. To prevent this case, this function splits the refused + * pages into 4KB pages and adds them into @prealloc_pages list. + * + * @ctl: pointer for the %struct vmballoon_ctl, which defines the operation. + */ +static void vmballoon_split_refused_pages(struct vmballoon_ctl *ctl) +{ + struct page *page, *tmp; + unsigned int i, order; + + order = vmballoon_page_order(ctl->page_size); + + list_for_each_entry_safe(page, tmp, &ctl->refused_pages, lru) { + list_del(&page->lru); + split_page(page, order); + for (i = 0; i < (1 << order); i++) + list_add(&page[i].lru, &ctl->prealloc_pages); + } + ctl->n_refused_pages = 0; +} + /** * vmballoon_inflate() - Inflate the balloon towards its target size. * @@ -1065,6 +1103,7 @@ static void vmballoon_inflate(struct vmballoon *b) struct vmballoon_ctl ctl = { .pages = LIST_HEAD_INIT(ctl.pages), .refused_pages = LIST_HEAD_INIT(ctl.refused_pages), + .prealloc_pages = LIST_HEAD_INIT(ctl.prealloc_pages), .page_size = b->max_page_size, .op = VMW_BALLOON_INFLATE }; @@ -1112,10 +1151,10 @@ static void vmballoon_inflate(struct vmballoon *b) break; /* - * Ignore errors from locking as we now switch to 4k - * pages and we might get different errors. + * Split the refused pages to 4k. This will also empty + * the refused pages list. */ - vmballoon_release_refused_pages(b, &ctl); + vmballoon_split_refused_pages(&ctl); ctl.page_size--; } @@ -1129,6 +1168,8 @@ static void vmballoon_inflate(struct vmballoon *b) */ if (ctl.n_refused_pages != 0) vmballoon_release_refused_pages(b, &ctl); + + vmballoon_release_page_list(&ctl.prealloc_pages, NULL, ctl.page_size); } /** -- 2.19.1