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[35.169.212.159]) by smtp.gmail.com with ESMTPSA id w185sm4618092qkd.30.2021.08.06.04.46.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Aug 2021 04:46:55 -0700 (PDT) From: SeongJae Park X-Google-Original-From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , SeongJae Park , Jonathan.Cameron@Huawei.com, acme@kernel.org, alexander.shishkin@linux.intel.com, amit@kernel.org, benh@kernel.crashing.org, brendanhiggins@google.com, corbet@lwn.net, david@redhat.com, dwmw@amazon.com, elver@google.com, fan.du@intel.com, foersleo@amazon.de, greg@kroah.com, gthelen@google.com, guoju.fgj@alibaba-inc.com, jgowans@amazon.com, joe@perches.com, mgorman@suse.de, mheyne@amazon.de, minchan@kernel.org, mingo@redhat.com, namhyung@kernel.org, peterz@infradead.org, riel@surriel.com, rientjes@google.com, rostedt@goodmis.org, rppt@kernel.org, shakeelb@google.com, shuah@kernel.org, sieberf@amazon.com, snu@zelle79.org, vbabka@suse.cz, vdavydov.dev@gmail.com, zgf574564920@gmail.com, linux-damon@amazon.com, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v34 07/13] mm/damon: Implement a debugfs-based user space interface Date: Fri, 6 Aug 2021 11:46:44 +0000 Message-Id: <20210806114645.6777-1-sjpark@amazon.de> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210805174304.3c3d8c8ee971bc9ddf6988af@linux-foundation.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: SeongJae Park On Thu, 5 Aug 2021 17:43:04 -0700 Andrew Morton wrote: > On Fri, 16 Jul 2021 08:14:43 +0000 SeongJae Park wrote: > > > From: SeongJae Park > > > > DAMON is designed to be used by kernel space code such as the memory > > management subsystems, and therefore it provides only kernel space API. > > That said, letting the user space control DAMON could provide some > > benefits to them. For example, it will allow user space to analyze > > their specific workloads and make their own special optimizations. > > > > For such cases, this commit implements a simple DAMON application kernel > > module, namely 'damon-dbgfs', which merely wraps the DAMON api and > > exports those to the user space via the debugfs. > > > > ... > > > > +static int __init damon_dbgfs_init(void) > > +{ > > + int rc; > > + > > + dbgfs_ctxs = kmalloc(sizeof(*dbgfs_ctxs), GFP_KERNEL); > > + if (!dbgfs_ctxs) { > > + pr_err("%s: dbgfs ctxs alloc failed\n", __func__); > > + return -ENOMEM; > > + } > > + dbgfs_ctxs[0] = dbgfs_new_ctx(); > > + if (!dbgfs_ctxs[0]) { > > + kfree(dbgfs_ctxs); > > + pr_err("%s: dbgfs ctx alloc failed\n", __func__); > > + return -ENOMEM; > > + } > > checkpatch points out that the "alloc failed" messages are unneeded - > kmalloc(GFP_KERNEL) will have already emitted a stack trace. Is this > fixup OK? Yes, of course. I also see you already kindly applied this in the -mm tree[1], appreciate! [1] https://www.ozlabs.org/~akpm/mmotm/broken-out/mm-damon-implement-a-debugfs-based-user-space-interface-fix.patch Thanks, SeongJae Park [...]