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Fri, 13 Mar 2020 13:17:01 -0700 (PDT) Received: from localhost.localdomain ([2a02:2450:10d2:194d:6183:2c38:fb6d:576a]) by smtp.gmail.com with ESMTPSA id d7sm7634380wrc.25.2020.03.13.13.16.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Mar 2020 13:17:00 -0700 (PDT) From: SeongJae Park To: Jonathan Cameron Cc: SeongJae Park , akpm@linux-foundation.org, SeongJae Park , aarcange@redhat.com, yang.shi@linux.alibaba.com, acme@kernel.org, alexander.shishkin@linux.intel.com, amit@kernel.org, brendan.d.gregg@gmail.com, brendanhiggins@google.com, cai@lca.pw, colin.king@canonical.com, corbet@lwn.net, dwmw@amazon.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, rientjes@google.com, rostedt@goodmis.org, shuah@kernel.org, sj38.park@gmail.com, vbabka@suse.cz, vdavydov.dev@gmail.com, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Re: [PATCH v6 02/14] mm/damon: Implement region based sampling Date: Fri, 13 Mar 2020 21:16:49 +0100 Message-Id: <20200313201649.26646-1-sj38.park@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200313172954.00001f3c@Huawei.com> (raw) 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 Fri, 13 Mar 2020 17:29:54 +0000 Jonathan Cameron wrote: > On Mon, 24 Feb 2020 13:30:35 +0100 > SeongJae Park wrote: > > > From: SeongJae Park > > > > This commit implements DAMON's basic access check and region based > > sampling mechanisms. This change would seems make no sense, mainly > > because it is only a part of the DAMON's logics. Following two commits > > will make more sense. > > [...] > > Came across a minor issue inline. kthread_run calls kthread_create. > That gives a potential sleep while atomic issue given the spin lock. > > Can probably be fixed by preallocating the thread then starting it later. > > Jonathan [...] > > +/* > > + * Start or stop the kdamond > > + * > > + * Returns 0 if success, negative error code otherwise. > > + */ > > +static int damon_turn_kdamond(struct damon_ctx *ctx, bool on) > > +{ > > + spin_lock(&ctx->kdamond_lock); > > + ctx->kdamond_stop = !on; > > + if (!ctx->kdamond && on) { > > + ctx->kdamond = kthread_run(kdamond_fn, ctx, "kdamond"); > > Can't do this under a spin lock. Good catch! And, agree to your suggestion. I will fix this in that way! Thanks, SeongJae Park