From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0F4FD539B for ; Mon, 15 Aug 2022 23:42:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 649B6C433D6; Mon, 15 Aug 2022 23:42:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1660606932; bh=58yaH86pz9K1ViOeBYMbEaj6JwLLYw1QuwMYWbFIqSU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Z5tfJVQnWKVAG16qIRgqi3fCmE3mTSQw0KPhfX3Q6aJIooYnLto5EuCtluPfX7DAZ Pr9ppSo8LDcHBOoy8cPr6L3pqYg3Qtj2dw17v1972R+12v/7HuZtLP+ScPG9jfixwW PkPCrnlbx7g4PXj4hEkVpBa/F9sOJgvVXjk+poFANQBGkzM6V4os/7/Ufpz3aftUec UPC+cGIfbQmMU2r5PfNihQB95A7s6P3flii9RewL0DG6m7AWY2kfhR0UQ6ngla+93L HzjpIZNnQWfZQdytFtmg0gCzxv9cK1rP4pu3d79+IPJkIkNleLqWtQ7u9BeDUHfV0R SvwSwFi80YRpQ== From: SeongJae Park To: "Pulavarty, Badari" Cc: SeongJae Park , "damon@lists.linux.dev" , "linux-mm@kvack.org" Subject: RE: [PATCH] DAMON dbgfs_mk_context() error handling Date: Mon, 15 Aug 2022 23:42:10 +0000 Message-Id: <20220815234210.95016-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Badari, On Mon, 15 Aug 2022 21:51:04 +0000 "Pulavarty, Badari" wrote: > [-- Attachment #1: Type: text/plain, Size: 350 bytes --] > > Hi SI, > > > Nice finding, thank you! But, the return value of the debugfs call is intentionally ignored[2]. How about doing the duplicated name check in > > dbgfs_mk_context() itself before the debugfs_create_dir() call? Please don't unwrap wrapped message. My monitor is not so wide :'( > > > > [2] https://lore.kernel.org/linux-mm/20210205155902.31102-1-sjpark@amazon.com/ > > How about this? > > Thanks, > Badari > > > > [-- Attachment #2: damon-mkcontext-fix.patch --] > [-- Type: application/octet-stream, Size: 858 bytes --] Could you please don't send a patch as an attached file of the mail but put it in the mail body so that we can easily read the patch and comment in line? > > damon dbgfs_mk_context() should check to make sure there is no existing > context with the same name. Otherwise, it will cause failure when we > enabling the monitor. > > Test case: > > echo "off" > /sys/kernel/debug/damon/monitor_on > echo "abc" > /sys/kernel/debug/damon/mk_context > echo "abc" > /sys/kernel/debug/damon/mk_context > echo > /sys/kernel/debug/damon/abc/target_ids > echo "on" > /sys/kernel/debug/damon/monitor_on <<< fails > > Signed-off-by: Badari Pulavarty > --- It would be good to put the changelog of this patch here: https://docs.kernel.org/process/submitting-patches.html#the-canonical-patch-format > --- a/mm/damon/dbgfs.c 2022-08-15 14:27:38.308806431 -0700 > +++ b/mm/damon/dbgfs.c 2022-08-15 14:33:31.661163048 -0700 > @@ -817,6 +817,12 @@ > if (!root) > return -ENOENT; > > + new_dir = debugfs_lookup(name, root); > + if (new_dir) { > + dput(new_dir); > + return -EEXIST; > + } > + The change looks ok to me at a glance, but the attached file seems not an appropriate patch. Could you please repost this as a formal patch as suggested for a better review? Thanks, SJ > new_dir = debugfs_create_dir(name, root); > dbgfs_dirs[dbgfs_nr_ctxs] = new_dir;