From patchwork Sun Jul 5 15:55:58 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Coly Li X-Patchwork-Id: 11644533 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C75C213B4 for ; Sun, 5 Jul 2020 15:56:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B8F8F20737 for ; Sun, 5 Jul 2020 15:56:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727893AbgGEP4l (ORCPT ); Sun, 5 Jul 2020 11:56:41 -0400 Received: from mx2.suse.de ([195.135.220.15]:38272 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727843AbgGEP4k (ORCPT ); Sun, 5 Jul 2020 11:56:40 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 736E6AC52; Sun, 5 Jul 2020 15:56:39 +0000 (UTC) From: Coly Li To: linux-bcache@vger.kernel.org Cc: linux-block@vger.kernel.org, Coly Li Subject: [RFC PATCH 13/16] bcache: handle btree node memory allocation properly for bucket size > 8MB Date: Sun, 5 Jul 2020 23:55:58 +0800 Message-Id: <20200705155601.5404-14-colyli@suse.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200705155601.5404-1-colyli@suse.de> References: <20200705155601.5404-1-colyli@suse.de> MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Currently the bcache internal btree node occupies a whole bucket. When loading the btree node from cache device into memory, mca_data_alloc() will call bch_btree_keys_alloc() to allocate memory for the whole bucket size, ilog2(b->c->btree_pages) is send to bch_btree_keys_alloc() as the parameter 'page_order'. c->btree_pages is set as bucket_pages() in bch_cache_set_alloc(), for bucket size > 8MB, ilog2(b->c->btree_pages) is 12 for 4KB page size. By default the maximum page order __get_free_pages() accepts is MAX_ORDER (11), in this condition bch_btree_keys_alloc() will always fail. Because of other over-page-order allocation failure fails the cache device registration, such btree node allocation failure wasn't observed during runtime. After other blocking page allocation failures for bucket size > 8MB, this btree node allocation issue may trigger potentical risk e.g. infinite dead-loop to retry btree node allocation after failure. This patch fixes the potential problem by setting c->btree_pages to meta_bucket_pages() in bch_cache_set_alloc(). In the condition that bucket size > 8MB, meta_bucket_pages() will always return a number which won't exceed the maximum page order of the buddy allocator. Signed-off-by: Coly Li --- drivers/md/bcache/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index b0e23012d6c1..2da6d5aa8c63 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -1860,7 +1860,7 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb) c->nr_uuids = meta_bucket_bytes(&c->sb) / sizeof(struct uuid_entry); c->devices_max_used = 0; atomic_set(&c->attached_dev_nr, 0); - c->btree_pages = bucket_pages(c); + c->btree_pages = meta_bucket_pages(&c->sb); if (c->btree_pages > BTREE_MAX_PAGES) c->btree_pages = max_t(int, c->btree_pages / 4, BTREE_MAX_PAGES);