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X-CSE-ConnectionGUID: O2hm+Ks1Tc+UW/kV6VndGQ== X-CSE-MsgGUID: 6pjwxM0iREKdGNcXzaIIyQ== X-IronPort-AV: E=McAfee;i="6700,10204,11128"; a="18010085" X-IronPort-AV: E=Sophos;i="6.09,196,1716274800"; d="scan'208";a="18010085" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Jul 2024 18:54:13 -0700 X-CSE-ConnectionGUID: s2Qi/WdoRquWjzTeorG42Q== X-CSE-MsgGUID: QO1rVt3IRMWuZ6BRmT06Hg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.09,196,1716274800"; d="scan'208";a="47960876" Received: from unknown (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Jul 2024 18:54:11 -0700 From: "Huang, Ying" To: Yafang Shao Cc: akpm@linux-foundation.org, mgorman@techsingularity.net, linux-mm@kvack.org Subject: Re: [PATCH 1/3] mm/page_alloc: A minor fix to the calculation of pcp->free_count In-Reply-To: <20240707094956.94654-2-laoar.shao@gmail.com> (Yafang Shao's message of "Sun, 7 Jul 2024 17:49:54 +0800") References: <20240707094956.94654-1-laoar.shao@gmail.com> <20240707094956.94654-2-laoar.shao@gmail.com> Date: Wed, 10 Jul 2024 09:52:20 +0800 Message-ID: <87cynmau97.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: A56D21C0005 X-Stat-Signature: byiy55od3z46hsczutfou4xoi93uij1r X-HE-Tag: 1720576453-749890 X-HE-Meta: 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 5mVjEmN4 xxUxBG+yZpzXgSgTzk9+qp4jbKD0b/qKmYqqtSpL81m247Oxf2z9OUFs3HtOkx4oStT+pMZA6Ue/KqqfQHbd8rTzWpP8WeK0Cpb0CrlcpxRemlnt6jaUYuIw6p4bbsVvF6IHqXN+VVJN0wO6q9HjXetfzcOP41QTQCoH2ZYGIWAKEK3JA+jyaeA6q630XOlaTxZsTifBdEsh/vv96BrulJCJF5dytDf+y/eUunYO8GmYCrFGZug75QqgbwSaIcnFRpqND1ncq1bX+T6yoGD2CJhDNyWPZxmsQggZvuBxXzYcK6KvXHIQC8fNA2Q== 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: Yafang Shao writes: > Currently, At worst, the pcp->free_count can be > (batch - 1 + (1 << MAX_ORDER)), which may exceed the expected max value of > (batch << CONFIG_PCP_BATCH_SCALE_MAX). > > This issue was identified through code review, and no real problems have > been observed. > > Signed-off-by: Yafang Shao > Cc: "Huang, Ying" LGTM, Thanks! Reviewed-by: "Huang, Ying" > --- > mm/page_alloc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 2e22ce5675ca..8e2f4e1ab4f2 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2534,7 +2534,8 @@ static void free_unref_page_commit(struct zone *zone, struct per_cpu_pages *pcp, > pcp->flags &= ~PCPF_PREV_FREE_HIGH_ORDER; > } > if (pcp->free_count < (batch << CONFIG_PCP_BATCH_SCALE_MAX)) > - pcp->free_count += (1 << order); > + pcp->free_count = min(pcp->free_count + (1 << order), > + batch << CONFIG_PCP_BATCH_SCALE_MAX); > high = nr_pcp_high(pcp, zone, batch, free_high); > if (pcp->count >= high) { > free_pcppages_bulk(zone, nr_pcp_free(pcp, batch, high, free_high),