From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f72.google.com (mail-pg0-f72.google.com [74.125.83.72]) by kanga.kvack.org (Postfix) with ESMTP id 532996B000C for ; Wed, 21 Mar 2018 00:38:24 -0400 (EDT) Received: by mail-pg0-f72.google.com with SMTP id v126so118526pgb.23 for ; Tue, 20 Mar 2018 21:38:24 -0700 (PDT) Received: from mailout4.samsung.com (mailout4.samsung.com. [203.254.224.34]) by mx.google.com with ESMTPS id b7si2219038pgc.551.2018.03.20.21.38.22 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 20 Mar 2018 21:38:23 -0700 (PDT) Received: from epcas5p3.samsung.com (unknown [182.195.41.41]) by mailout4.samsung.com (KnoxPortal) with ESMTP id 20180321043820epoutp04554ef1e2f9ebf6d6fde07fa49f22a748~d1ZiPXRrN1601316013epoutp04k for ; Wed, 21 Mar 2018 04:38:20 +0000 (GMT) From: Maninder Singh Subject: [PATCH 1/1] mm/page_owner: fix recursion bug after changing skip entries Date: Wed, 21 Mar 2018 10:07:23 +0530 Message-Id: <1521607043-34670-1-git-send-email-maninder1.s@samsung.com> Content-Type: text/plain; charset="utf-8" References: Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org, vbabka@suse.cz, mhocko@suse.com, osalvador@techadventures.net, gregkh@linuxfoundation.org, ayush.m@samsung.com, guptap@codeaurora.org, vinmenon@codeaurora.org, gomonovych@gmail.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, a.sahrawat@samsung.com, pankaj.m@samsung.com, Maninder Singh , Vaneet Narang This patch fixes "5f48f0bd4e368425db4424b9afd1bd251d32367a". (mm, page_owner: skip unnecessary stack_trace entries) Because if we skip first two entries then logic of checking count value as 2 for recursion is broken and code will go in one depth recursion. so we need to check only one call of _RET_IP(__set_page_owner) while checking for recursion. Current Backtrace while checking for recursion:- (save_stack) from (__set_page_owner) // (But recursion returns true here) (__set_page_owner) from (get_page_from_freelist) (get_page_from_freelist) from (__alloc_pages_nodemask) (__alloc_pages_nodemask) from (depot_save_stack) (depot_save_stack) from (save_stack) // recursion should return true here (save_stack) from (__set_page_owner) (__set_page_owner) from (get_page_from_freelist) (get_page_from_freelist) from (__alloc_pages_nodemask+) (__alloc_pages_nodemask) from (depot_save_stack) (depot_save_stack) from (save_stack) (save_stack) from (__set_page_owner) (__set_page_owner) from (get_page_from_freelist) Correct Backtrace with fix: (save_stack) from (__set_page_owner) // recursion returned true here (__set_page_owner) from (get_page_from_freelist) (get_page_from_freelist) from (__alloc_pages_nodemask+) (__alloc_pages_nodemask) from (depot_save_stack) (depot_save_stack) from (save_stack) (save_stack) from (__set_page_owner) (__set_page_owner) from (get_page_from_freelist) Signed-off-by: Maninder Singh Signed-off-by: Vaneet Narang --- mm/page_owner.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/page_owner.c b/mm/page_owner.c index 8592543..46ab1c4 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -123,13 +123,13 @@ void __reset_page_owner(struct page *page, unsigned int order) static inline bool check_recursive_alloc(struct stack_trace *trace, unsigned long ip) { - int i, count; + int i; if (!trace->nr_entries) return false; - for (i = 0, count = 0; i < trace->nr_entries; i++) { - if (trace->entries[i] == ip && ++count == 2) + for (i = 0; i < trace->nr_entries; i++) { + if (trace->entries[i] == ip) return true; } -- 1.7.1