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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E3D7AC433F5 for ; Wed, 20 Oct 2021 01:21:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BC6D361004 for ; Wed, 20 Oct 2021 01:21:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229698AbhJTBXs (ORCPT ); Tue, 19 Oct 2021 21:23:48 -0400 Received: from out30-43.freemail.mail.aliyun.com ([115.124.30.43]:43384 "EHLO out30-43.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229639AbhJTBXs (ORCPT ); Tue, 19 Oct 2021 21:23:48 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04407;MF=xhao@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0Ut-kjiw_1634692891; Received: from B-X3VXMD6M-2058.local(mailfrom:xhao@linux.alibaba.com fp:SMTPD_---0Ut-kjiw_1634692891) by smtp.aliyun-inc.com(127.0.0.1); Wed, 20 Oct 2021 09:21:32 +0800 From: Xin Hao Reply-To: xhao@linux.alibaba.com Subject: Re: [PATCH v2 2/2] mm/damon/dbgfs: Add adaptive_targets list check before enable monitor_on To: SeongJae Park Cc: sjpark@amazon.de, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20211019154243.17474-1-sj@kernel.org> Message-ID: <7376a28e-ac8d-06d0-fa05-81656cd3a994@linux.alibaba.com> Date: Wed, 20 Oct 2021 09:21:30 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20211019154243.17474-1-sj@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/10/19 下午11:42, SeongJae Park wrote: > Hello Xin, > > On Tue, 19 Oct 2021 22:26:04 +0800 Xin Hao wrote: > >> When the ctx->adaptive_targets list is empty, >> i did some test on monitor_on interface like this. > s/i/I/ thanks >> echo on > /sys/kernel/debug/damon/monitor_on >> [ 851.988307] damon: kdamond (5390) starts > Could you please add four spaces in the beginning of this example terminal > outputs? Also, I think confirming targets are empty like below before writing > 'on' could make this example better. > > # cat /sys/kernel/debug/damon/target_ids > # > > or, like below. > > # echo > /sys/kernel/debug/damon/target_ids Oh! thank you so much, i will fix it. > >> Though the ctx->adaptive_targets list is empty, but the >> kthread_run still be called, and the kdamond.x thread still >> be created, this is meaningless. >> >> So there adds a judgment in 'dbgfs_monitor_on_write', >> if the ctx->adaptive_targets list is empty, return -EINVAL. >> >> Signed-off-by: Xin Hao >> --- >> include/linux/damon.h | 1 + >> mm/damon/core.c | 5 +++++ >> mm/damon/dbgfs.c | 10 ++++++++-- >> 3 files changed, 14 insertions(+), 2 deletions(-) >> >> diff --git a/include/linux/damon.h b/include/linux/damon.h >> index 715dadd21f7c..06acf73fe9db 100644 >> --- a/include/linux/damon.h >> +++ b/include/linux/damon.h >> @@ -316,6 +316,7 @@ void damon_destroy_scheme(struct damos *s); >> >> struct damon_target *damon_new_target(unsigned long id); >> void damon_add_target(struct damon_ctx *ctx, struct damon_target *t); >> +int damon_target_empty(struct damon_ctx *ctx); > Seems 'bool' would be better for the return type? ok! > >> void damon_free_target(struct damon_target *t); >> void damon_destroy_target(struct damon_target *t); >> unsigned int damon_nr_regions(struct damon_target *t); >> diff --git a/mm/damon/core.c b/mm/damon/core.c >> index 2f6785737902..c651b49249e5 100644 >> --- a/mm/damon/core.c >> +++ b/mm/damon/core.c >> @@ -156,6 +156,11 @@ void damon_add_target(struct damon_ctx *ctx, struct damon_target *t) >> list_add_tail(&t->list, &ctx->adaptive_targets); >> } >> >> +int damon_target_empty(struct damon_ctx *ctx) >> +{ >> + return list_empty(&ctx->adaptive_targets); >> +} >> + >> static void damon_del_target(struct damon_target *t) >> { >> list_del(&t->list); >> diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c >> index 38188347d8ab..bac42dd358d1 100644 >> --- a/mm/damon/dbgfs.c >> +++ b/mm/damon/dbgfs.c >> @@ -865,9 +865,15 @@ static ssize_t dbgfs_monitor_on_write(struct file *file, >> return -EINVAL; >> } >> >> - if (!strncmp(kbuf, "on", count)) >> + if (!strncmp(kbuf, "on", count)) { >> + int i; >> + >> + for (i = 0; i < dbgfs_nr_ctxs; i++) { >> + if (damon_target_empty(dbgfs_ctxs[i])) >> + return -EINVAL; >> + } >> err = damon_start(dbgfs_ctxs, dbgfs_nr_ctxs); >> - else if (!strncmp(kbuf, "off", count)) >> + } else if (!strncmp(kbuf, "off", count)) >> err = damon_stop(dbgfs_ctxs, dbgfs_nr_ctxs); >> else >> err = -EINVAL; > Please use braces for all above branches: Ok，i will correct it. > > https://docs.kernel.org/process/coding-style.html#placing-braces-and-spaces > > > Thanks, > SJ > >> -- >> 2.31.0 -- Best Regards! Xin Hao