From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CF25BC2D0E4 for ; Fri, 27 Nov 2020 15:49:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8A4462223F for ; Fri, 27 Nov 2020 15:49:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730987AbgK0Ptr (ORCPT ); Fri, 27 Nov 2020 10:49:47 -0500 Received: from mx2.suse.de ([195.135.220.15]:38202 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730675AbgK0Ptr (ORCPT ); Fri, 27 Nov 2020 10:49:47 -0500 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 67FC6AE30; Fri, 27 Nov 2020 15:49:46 +0000 (UTC) Subject: Re: [PATCH] mm: cma: improve pr_debug log in cma_release() To: Charan Teja Reddy , akpm@linux-foundation.org, iamjoonsoo.kim@lge.com, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, vinmenon@codeaurora.org References: <1606318341-29521-1-git-send-email-charante@codeaurora.org> From: Vlastimil Babka Message-ID: Date: Fri, 27 Nov 2020 16:49:43 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <1606318341-29521-1-git-send-email-charante@codeaurora.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/25/20 4:32 PM, Charan Teja Reddy wrote: > It is required to print 'count' of pages, along with the pages, passed > to cma_release to debug the cases of mismatched count value passed > between cma_alloc() and cma_release() from a code path. > > As an example, consider the below scenario: > 1) CMA pool size is 4MB and > 2) User doing the erroneous step of allocating 2 pages but freeing 1 > page in a loop from this CMA pool. > The step 2 causes cma_alloc() to return NULL at one point of time > because of -ENOMEM condition. > > And the current pr_debug logs is not giving the info about these types > of allocation patterns because of count value not being printed in > cma_release(). > > We are printing the count value in the trace logs, just extend the same > to pr_debug logs too. > > Signed-off-by: Charan Teja Reddy Acked-by: Vlastimil Babka > --- > mm/cma.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/cma.c b/mm/cma.c > index 7f415d7..07c904b 100644 > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -512,7 +512,7 @@ bool cma_release(struct cma *cma, const struct page *pages, unsigned int count) > if (!cma || !pages) > return false; > > - pr_debug("%s(page %p)\n", __func__, (void *)pages); > + pr_debug("%s(page %p, count %zu)\n", __func__, (void *)pages, count); > > pfn = page_to_pfn(pages); > >