From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S944973AbcJSRZD (ORCPT ); Wed, 19 Oct 2016 13:25:03 -0400 Received: from gum.cmpxchg.org ([85.214.110.215]:60030 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S944733AbcJSRYz (ORCPT ); Wed, 19 Oct 2016 13:24:55 -0400 From: Johannes Weiner To: Andrew Morton Cc: Linus Torvalds , Jan Kara , Dave Jones , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: [PATCH 5/5] mm: workingset: turn shadow node shrinker bugs into warnings Date: Wed, 19 Oct 2016 13:24:28 -0400 Message-Id: <20161019172428.7649-6-hannes@cmpxchg.org> X-Mailer: git-send-email 2.10.0 In-Reply-To: <20161019172428.7649-1-hannes@cmpxchg.org> References: <20161019172428.7649-1-hannes@cmpxchg.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When the shadow page shrinker tries to reclaim a radix tree node but finds it in an unexpected state--it should contain no pages, and non-zero shadow entries--there is no need to kill the executing task or even the entire system. Warn about the invalid state, then leave that tree node be. Simply don't put it back on the shadow LRU for future reclaim and move on. Signed-off-by: Johannes Weiner --- mm/workingset.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/mm/workingset.c b/mm/workingset.c index 617475f529f4..5f07db171c03 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -418,23 +418,28 @@ static enum lru_status shadow_lru_isolate(struct list_head *item, * no pages, so we expect to be able to remove them all and * delete and free the empty node afterwards. */ - BUG_ON(!workingset_node_shadows(node)); - BUG_ON(workingset_node_pages(node)); + if (WARN_ON_ONCE(!workingset_node_shadows(node))) + goto out_invalid; + if (WARN_ON_ONCE(workingset_node_pages(node))) + goto out_invalid; for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) { if (node->slots[i]) { - BUG_ON(!radix_tree_exceptional_entry(node->slots[i])); + if (WARN_ON_ONCE(!radix_tree_exceptional_entry(node->slots[i]))) + goto out_invalid; node->slots[i] = NULL; workingset_node_shadows_dec(node); - BUG_ON(!mapping->nrexceptional); + if (WARN_ON_ONCE(!mapping->nrexceptional)) + goto out_invalid; mapping->nrexceptional--; } } - BUG_ON(workingset_node_shadows(node)); + if (WARN_ON_ONCE(workingset_node_shadows(node))) + goto out_invalid; inc_node_state(page_pgdat(virt_to_page(node)), WORKINGSET_NODERECLAIM); - if (!__radix_tree_delete_node(&mapping->page_tree, node)) - BUG(); + __radix_tree_delete_node(&mapping->page_tree, node); +out_invalid: spin_unlock(&mapping->tree_lock); ret = LRU_REMOVED_RETRY; out: -- 2.10.0