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 12820C433F5 for ; Wed, 20 Oct 2021 10:04:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E8819610D0 for ; Wed, 20 Oct 2021 10:04:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229771AbhJTKGR (ORCPT ); Wed, 20 Oct 2021 06:06:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:43952 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230091AbhJTKGJ (ORCPT ); Wed, 20 Oct 2021 06:06:09 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id DEDB2610D0; Wed, 20 Oct 2021 10:03:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1634724235; bh=lrPMdPFAqscn7Rpjk8b6fNTYESlFC3wEHYb4rxUKF8g=; h=From:To:Cc:Subject:Date:In-Reply-To:From; b=AhjfgR+kfD0iXHN8WahIBAiZsXceoYRbLnAySaQTa/55pvc89T2Oqo748oiscc+Ej hFml1/ADubHTsjE4LVECHcS3/Vla2ybT/XiQWK60fMQ55A4k4Bw8UOV4GFtAseeMOv UDmhGGqRaVPs7g6FeLC0xKsQIPrsD1YTWQlbT7KWEieYaGvNXoUhqQ5u5DbVrxnfX9 Bt4UoAYY5kNd76Oc8F1hMebegiSzpAKliDpetlURdSGciiH3JPU9ARMi7Ju/qEXFoB 92tbrmTLZlt0XLkNGZ60W5z2fJU3QX1X6eYLDCy/FmVuPUzQfDk4MFjt4crnUqK1Ln dvu8/SYrioJ2g== From: SeongJae Park To: Xin Hao Cc: sjpark@amazon.de, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V4 2/2] mm/damon/dbgfs: Add adaptive_targets list check before enable monitor_on Date: Wed, 20 Oct 2021 10:03:52 +0000 Message-Id: <20211020100352.31747-1-sj@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <0a60a6e8ec9d71989e0848a4dc3311996ca3b5d4.1634720326.git.xhao@linux.alibaba.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 20 Oct 2021 17:03:01 +0800 Xin Hao wrote: > When the ctx->adaptive_targets list is empty, > I did some test on monitor_on interface like this. > > # cat /sys/kernel/debug/damon/target_ids > # > # echo on > /sys/kernel/debug/damon/monitor_on > # damon: kdamond (5390) starts > > 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 Reviewed-by: SeongJae Park Thanks, SJ > --- > include/linux/damon.h | 1 + > mm/damon/core.c | 5 +++++ > mm/damon/dbgfs.c | 15 ++++++++++++--- > 3 files changed, 18 insertions(+), 3 deletions(-) > > diff --git a/include/linux/damon.h b/include/linux/damon.h > index 715dadd21f7c..4fce5f1f6dad 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); > +bool damon_targets_empty(struct damon_ctx *ctx); > 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..c3a1374dbe0b 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); > } > > +bool damon_targets_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 c90988a20fa4..a02cf6bee8e8 100644 > --- a/mm/damon/dbgfs.c > +++ b/mm/damon/dbgfs.c > @@ -861,12 +861,21 @@ 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_targets_empty(dbgfs_ctxs[i])) { > + kfree(kbuf); > + return -EINVAL; > + } > + } > ret = damon_start(dbgfs_ctxs, dbgfs_nr_ctxs); > - else if (!strncmp(kbuf, "off", count)) > + } else if (!strncmp(kbuf, "off", count)) { > ret = damon_stop(dbgfs_ctxs, dbgfs_nr_ctxs); > - else > + } else { > ret = -EINVAL; > + } > > if (!ret) > ret = count; > -- > 2.31.0