From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-204.mta1.migadu.com [95.215.58.204]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 46DA6476697 for ; Thu, 13 Aug 2026 17:14:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.204 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786641301; cv=none; b=Zy5zIatSWq3nYWUGnHs59VvuQT/khGdCzL2qSG6tmtXZuKFLUueXID/v1js0pXM4fo8nuk3uYJMFsbpoRppf5hp1JNcAQ1+J0iPrA4uymmyLAMO9XtBUnwNH3kEU6jmd3rpy+vfznub8Q1SB0LIKd81NQcvwfetqPBMmXgHPKRM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786641301; c=relaxed/simple; bh=Yec5Wj8ZUY9zXGuHPs7l8wD80d+XYwicM6WJm2aA3IY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=q6vbLQDliTsK+H80S6xzSQIAY3DtInYmmEmtMLbc3GqwooOCl/0i9auyMMegZHmSa4faMcUAhN7wz3JU9u+axOZFXBnh4UPTqPV9QKxEJePZejONBezBfAyrWUZTCWsMO2ThT1RdwrXAP2hKFTN2AXkEqae1RRHJ3riHsHKHOaI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=ONfwZ9zu; arc=none smtp.client-ip=95.215.58.204 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="ONfwZ9zu" X-Envelope-To: oe-lkp@lists.linux.dev DKIM-Signature: a=rsa-sha256; bh=Yec5Wj8ZUY9zXGuHPs7l8wD80d+XYwicM6WJm2aA3IY=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1786641297; v=1; x=1787246097; b=ONfwZ9zudG1WKFJK7xFgYirQ8JVn1gIlzoW/dJ7mi0E4EXMn2MZnW9CW8DkL1HjG6LuWNomN d1Tq2BsoJ7LSIvqrWlWHoHHFppUdWntH7FkCtvkS1szHo7K2KsAR4W6l8FXHEmi8VW+T1s/P7af EfjLvJwwVB0Hf05C8rvCoc0c= X-Envelope-To: oe-lkp@lists.linux.dev Received: from [IPV6:2a03:83e0:1126:4:9d:a05e:5bd8:c200] (2620:10d:c092:500::6:def8) by smtp.migadu.com with ESMTPS id de41cf8ec9c54807; Thu, 13 Aug 2026 17:14:57 +0000 X-Migadu-Flow: FLOW_OUT Message-ID: <017721a3-5eae-449e-8b86-75cffb503dd3@linux.dev> Date: Thu, 13 Aug 2026 18:14:50 +0100 Precedence: bulk X-Mailing-List: oe-lkp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [linux-next:master] [mm/vmpressure] ea928e9e18: stress-ng.mremap.ops_per_sec 36.2% regression To: Shakeel Butt , kernel test robot Cc: oe-lkp@lists.linux.dev, lkp@intel.com, Andrew Morton , David Hildenbrand , Johannes Weiner , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , =?UTF-8?Q?Michal_Koutn=C3=BD?= , Mike Rapoport , Roman Gushchin , Suren Baghdasaryan , Tejun Heo , Vlastimil Babka , linux-mm@kvack.org, cgroups@vger.kernel.org References: <202608131743.c6a7dda4-lkp@intel.com> Content-Language: en-US From: Usama Arif In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 13/08/2026 18:01, Shakeel Butt wrote: > On Thu, Aug 13, 2026 at 09:16:22PM +0800, kernel test robot wrote: >> >> >> Hello, >> >> kernel test robot noticed a 36.2% regression of stress-ng.mremap.ops_per_sec on: >> >> commit: ea928e9e18da682e9a5bc40aa862bff7ce5ae42e ("mm/vmpressure: move v1 userspace eventfd code into memcontrol-v1.c") https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master >> >> in testcase: stress-ng >> version: stress-ng-x86_64-29ce10a2c-1_20260712 >> with following parameters: >> >> nr_threads: 100% >> testtime: 60s >> test: mremap >> cpufreq_governor: performance >> >> >> >> config: x86_64-rhel-9.4 (CONFIG_MEMCG=y and CONFIG_MEMCG_V1 is not set) >> compiler: gcc-14 >> test machine: 256 threads 4 sockets INTEL(R) XEON(R) PLATINUM 8592+ (Emerald Rapids) with 256G memory >> >> (please refer to attached dmesg/kmsg for entire log/backtrace) >> > > Hi there, > > Can you please test the following patch and see if it fixes the regression? > > > From 84c0b05b3bc5cf73ee66ead75aafb1ad684462c3 Mon Sep 17 00:00:00 2001 > From: Shakeel Butt > Date: Thu, 13 Aug 2026 09:38:28 -0700 > Subject: [PATCH] memcg: keep vmstats_percpu off the memory_events[] cacheline > > Signed-off-by: Shakeel Butt > --- > include/linux/memcontrol.h | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index e78bc98ab229..e25d5b9a1db8 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -246,8 +246,13 @@ struct mem_cgroup { > /* handle for "memory.swap.events" */ > struct cgroup_file swap_events_file; > > - /* memory.stat */ > + /* Read-mostly. */ > struct memcg_vmstats *vmstats; > + struct memcg_vmstats_percpu __percpu *vmstats_percpu; > + int kmemcg_id; > + > + /* Write-hot from here on; do not let it share with the above. */ > + CACHELINE_PADDING(_pad_); > > /* memory.events */ > atomic_long_t memory_events[MEMCG_NR_MEMORY_EVENTS]; > @@ -266,9 +271,6 @@ struct mem_cgroup { > #if BITS_PER_LONG < 64 > seqlock_t socket_pressure_seqlock; > #endif > - int kmemcg_id; > - > - struct memcg_vmstats_percpu __percpu *vmstats_percpu; > > #ifdef CONFIG_CGROUP_WRITEBACK > struct list_head cgwb_list; I was currently testing this diff, not sure which one would be better. diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index e78bc98ab229b..215e2e87f42b2 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -268,10 +268,15 @@ struct mem_cgroup { #endif int kmemcg_id; - struct memcg_vmstats_percpu __percpu *vmstats_percpu; - #ifdef CONFIG_CGROUP_WRITEBACK struct list_head cgwb_list; +#endif + + /* Keep the hot per-CPU stats pointer away from memory event counters. */ + struct memcg_vmstats_percpu __percpu *vmstats_percpu + ____cacheline_aligned_in_smp; + +#ifdef CONFIG_CGROUP_WRITEBACK struct wb_domain cgwb_domain; struct memcg_cgwb_frn cgwb_frn[MEMCG_CGWB_FRN_CNT]; #endif