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Mon, 31 Aug 2020 11:08:50 -0700 (PDT) Date: Mon, 31 Aug 2020 20:08:44 +0200 From: Marco Elver To: SeongJae Park Cc: akpm@linux-foundation.org, SeongJae Park , Jonathan.Cameron@Huawei.com, aarcange@redhat.com, acme@kernel.org, alexander.shishkin@linux.intel.com, amit@kernel.org, benh@kernel.crashing.org, brendan.d.gregg@gmail.com, brendanhiggins@google.com, cai@lca.pw, colin.king@canonical.com, corbet@lwn.net, david@redhat.com, dwmw@amazon.com, fan.du@intel.com, foersleo@amazon.de, gthelen@google.com, irogers@google.com, jolsa@redhat.com, kirill@shutemov.name, mark.rutland@arm.com, mgorman@suse.de, minchan@kernel.org, mingo@redhat.com, namhyung@kernel.org, peterz@infradead.org, rdunlap@infradead.org, riel@surriel.com, rientjes@google.com, rostedt@goodmis.org, rppt@kernel.org, sblbir@amazon.com, shakeelb@google.com, shuah@kernel.org, sj38.park@gmail.com, snu@amazon.de, vbabka@suse.cz, vdavydov.dev@gmail.com, yang.shi@linux.alibaba.com, ying.huang@intel.com, zgf574564920@gmail.com, linux-damon@amazon.com, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC v8 01/10] mm/damon/debugfs: Allow users to set initial monitoring target regions Message-ID: <20200831180844.GA3992970@elver.google.com> References: <20200831104730.28970-1-sjpark@amazon.com> <20200831104730.28970-2-sjpark@amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200831104730.28970-2-sjpark@amazon.com> User-Agent: Mutt/1.14.4 (2020-06-18) X-Rspamd-Queue-Id: 5145918038E67 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Aug 31, 2020 at 12:47PM +0200, SeongJae Park wrote: [...] > diff --git a/mm/damon.c b/mm/damon.c > index 7e3c8c82a010..9815d22fc4de 100644 > --- a/mm/damon.c > +++ b/mm/damon.c > @@ -2001,6 +2001,147 @@ static ssize_t debugfs_record_write(struct file *file, > return ret; > } > > +static ssize_t sprint_init_regions(struct damon_ctx *c, char *buf, ssize_t len) > +{ > + struct damon_target *t; > + struct damon_region *r; > + int written = 0; > + int rc; > + > + damon_for_each_target(t, c) { > + damon_for_each_region(r, t) { > + rc = snprintf(&buf[written], len - written, > + "%lu %lu %lu\n", > + t->id, r->ar.start, r->ar.end); This most likely will not work as intended, because snprintf() returns "[...] the number of characters which would be generated for the given input, excluding the trailing null [...]". Would scnprintf() -- which returns "[...] the number of characters written into @buf not including the trailing '\0' [...]" -- do what you intended? > + if (!rc) > + return -ENOMEM; > + written += rc; > + } > + } > + return written; > +} [...]