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X-CSE-ConnectionGUID: uNdAyQyhT2GoIvAL0ANTsQ== X-CSE-MsgGUID: zrbctqh2TU+vxcKD+Mwi6Q== X-IronPort-AV: E=McAfee;i="6800,10657,11518"; a="79750524" X-IronPort-AV: E=Sophos;i="6.17,278,1747724400"; d="scan'208";a="79750524" Received: from orviesa005.jf.intel.com ([10.64.159.145]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Aug 2025 08:10:14 -0700 X-CSE-ConnectionGUID: e80qHBrnQ3+4tIioB2Gvuw== X-CSE-MsgGUID: gQ9FGlJyQies9g8Zki86eg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.17,278,1747724400"; d="scan'208";a="171290349" Received: from black.igk.intel.com ([10.91.253.5]) by orviesa005.jf.intel.com with ESMTP; 11 Aug 2025 08:10:07 -0700 Received: by black.igk.intel.com (Postfix, from userid 1003) id 7E14494; Mon, 11 Aug 2025 17:10:05 +0200 (CEST) Date: Mon, 11 Aug 2025 17:10:05 +0200 From: Andy Shevchenko To: Bhupesh Cc: akpm@linux-foundation.org, kernel-dev@igalia.com, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, oliver.sang@intel.com, lkp@intel.com, laoar.shao@gmail.com, pmladek@suse.com, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, arnaldo.melo@gmail.com, alexei.starovoitov@gmail.com, andrii.nakryiko@gmail.com, mirq-linux@rere.qmqm.pl, peterz@infradead.org, willy@infradead.org, david@redhat.com, viro@zeniv.linux.org.uk, keescook@chromium.org, ebiederm@xmission.com, brauner@kernel.org, jack@suse.cz, mingo@redhat.com, juri.lelli@redhat.com, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-trace-kernel@vger.kernel.org, kees@kernel.org, torvalds@linux-foundation.org Subject: Re: [PATCH v7 2/4] include: Set tsk->comm length to 64 bytes Message-ID: References: <20250811064609.918593-1-bhupesh@igalia.com> <20250811064609.918593-3-bhupesh@igalia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250811064609.918593-3-bhupesh@igalia.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo X-Stat-Signature: tyqzjf9ja5sajin5iqnq4yyc56tbk6wi X-Rspam-User: X-Rspamd-Queue-Id: 3C3868000F X-Rspamd-Server: rspam02 X-HE-Tag: 1754925015-471264 X-HE-Meta: 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 sIq5bZsj KFnoE+p6c7EuM4vqdQKS5UhaDJqtaGo6Vh+ONthl88Ugvf2K+5DiooRrbAxBo30cUkaNfOo2v8o0akHaeOivS+5hK/rFwX+bdcHMeiCBEJ1LKBOQp3zORT61/2jFAqZmT5rtNOmUI8wMxYPqHIEUlFCm/lmx2RjTmL7LAue0K7ecNjdwOUQR745jPx4Fia18UZVOpJrvqKcPbDunebnka/BQVuoXZJMPvtXDF7q9FnUDpVEc+DZZQcYJ9IJybJbqYH2XukEos2Ilzeh8IkNbn87c1ZbIcnwfkvHTbcfFwP/Vd+hluGSbON4hSBocHyapj6VlcqaZmjUrahDC+sbmrFbXdIg== 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: List-Subscribe: List-Unsubscribe: On Mon, Aug 11, 2025 at 12:16:07PM +0530, Bhupesh wrote: > Historically due to the 16-byte length of TASK_COMM_LEN, the > users of 'tsk->comm' are restricted to use a fixed-size target > buffer also of TASK_COMM_LEN for 'memcpy()' like use-cases. > > To fix the same, we now use a 64-byte TASK_COMM_EXT_LEN and > set the comm element inside 'task_struct' to the same length: > struct task_struct { > ..... > char comm[TASK_COMM_EXT_LEN]; > ..... > }; > > where TASK_COMM_EXT_LEN is 64-bytes. > > Note, that the existing users have not been modified to migrate to > 'TASK_COMM_EXT_LEN', in case they have hard-coded expectations of > dealing with only a 'TASK_COMM_LEN' long 'tsk->comm'. ... > - BUILD_BUG_ON(sizeof(from) != TASK_COMM_LEN); \ > + BUILD_BUG_ON(sizeof(from) < TASK_COMM_LEN); \ Wondering if we may convert this to static_assert(). (rather in a separate patch) -- With Best Regards, Andy Shevchenko