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Mon, 02 Mar 2026 11:43:14 -0800 (PST) Date: Mon, 2 Mar 2026 14:43:11 -0500 From: Johannes Weiner To: Jianyue Wu Cc: akpm@linux-foundation.org, shakeel.butt@linux.dev, mhocko@kernel.org, roman.gushchin@linux.dev, muchun.song@linux.dev, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, inwardvessel@gmail.com Subject: Re: [PATCH v4 1/1] mm: optimize stat output for 11% sys time reduce Message-ID: References: <20260122114242.72139-1-wujianyue000@gmail.com> <20260123150108.43443-1-wujianyue000@gmail.com> <20260123150108.43443-2-wujianyue000@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260123150108.43443-2-wujianyue000@gmail.com> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: B92AB1C000E X-Stat-Signature: 9h6ztmfzjwsbkaeogxpy1f7fqe7h85sg X-Rspam-User: X-HE-Tag: 1772480596-459159 X-HE-Meta: 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 /mJdMmdh KOwx4ysEO843TtCqNdvccLmUifnyS38O5eSmS5aFR7gW6xo4Rf3EFF6UD0zkLFn2mXy1DI7jzOWGjPAENrrhd6oIXdKbYoNMxofmvOPV7Lhni9l+VGhyvRf5LKxRrAS34euxlDfTOZl9QZc3X5VQbqJmwdiObsfNeH1hndyYX2VPFVHCrHnGn7EZibj1RLQd219lkucmEf/NLdvrL114Lu/jpWCeY08jCtpmcPk8X5endgIUVIx9iCO4/AC8K6Z3Io1JqeLB0RQq3i4O/kGszzrfpZKofRP8ABrrhotff5vJSUnDtZPJ0WtihQrBWrw8Vi5kd/m+pGgyNbwu1WZs1bTJ9Zuokv17HZaGaD87uwkMOMkPPKbriTMZxLfmUaWsbkOqiO4eFvUCM6kUoczSqfY1K7A== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jan 23, 2026 at 11:01:08PM +0800, Jianyue Wu wrote: > +void memcg_seq_buf_print_stat(struct seq_buf *s, const char *prefix, > + const char *name, char sep, u64 val) > +{ > + char num_buf[MEMCG_DEC_U64_MAX_LEN + 2]; /* +2 for separator and newline */ > + int num_len; > + > + /* Embed separator at the beginning */ > + num_buf[0] = sep; > + > + /* Convert number starting at offset 1 */ > + num_len = num_to_str(num_buf + 1, sizeof(num_buf) - 2, val, 0); > + if (num_len <= 0) > + return; > + > + /* Embed newline at the end */ > + num_buf[num_len + 1] = '\n'; > + > + if (prefix && *prefix && seq_buf_puts(s, prefix)) > + return; > + if (seq_buf_puts(s, name)) > + return; > + /* Output separator, value, and newline in one call */ > + seq_buf_putmem(s, num_buf, num_len + 2); You seem to be losing the \0 somewhere. I'm getting garbage at the end of memory.stat on mm-new: [...] thp_swpout_fallback 1212 hp_swpout_fallback 1212 hp_swpout_fallback 1054 907 1278 Dropping this patch fixes the issue.