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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 17 Jun 2019 07:54:02 +0100 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x5H6s1U951839090 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 17 Jun 2019 06:54:01 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3762AAE05D; Mon, 17 Jun 2019 06:54:01 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9FEDBAE051; Mon, 17 Jun 2019 06:53:59 +0000 (GMT) Received: from rapoport-lnx (unknown [9.148.8.53]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Mon, 17 Jun 2019 06:53:59 +0000 (GMT) Date: Mon, 17 Jun 2019 09:53:57 +0300 From: Mike Rapoport To: "Alastair D'Silva" Cc: alastair@d-silva.org, Andrew Morton , David Hildenbrand , Oscar Salvador , Michal Hocko , Pavel Tatashin , Wei Yang , Juergen Gross , Qian Cai , Thomas Gleixner , Ingo Molnar , Josh Poimboeuf , Jiri Kosina , Peter Zijlstra , Mukesh Ojha , Arun KS , Mike Rapoport , Baoquan He , Logan Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/5] mm/hotplug: Avoid RCU stalls when removing large amounts of memory References: <20190617043635.13201-1-alastair@au1.ibm.com> <20190617043635.13201-5-alastair@au1.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190617043635.13201-5-alastair@au1.ibm.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-TM-AS-GCONF: 00 x-cbid: 19061706-0012-0000-0000-00000329BB60 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19061706-0013-0000-0000-00002162D170 Message-Id: <20190617065357.GD16810@rapoport-lnx> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-17_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906170064 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: On Mon, Jun 17, 2019 at 02:36:30PM +1000, Alastair D'Silva wrote: > From: Alastair D'Silva > > When removing sufficiently large amounts of memory, we trigger RCU stall > detection. By periodically calling cond_resched(), we avoid bogus stall > warnings. > > Signed-off-by: Alastair D'Silva > --- > mm/memory_hotplug.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index e096c987d261..382b3a0c9333 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -578,6 +578,9 @@ void __remove_pages(struct zone *zone, unsigned long phys_start_pfn, > __remove_section(zone, __pfn_to_section(pfn), map_offset, > altmap); > map_offset = 0; > + > + if (!(i & 0x0FFF)) No magic numbers please. And a comment would be appreciated. > + cond_resched(); > } > > set_zone_contiguous(zone); > -- > 2.21.0 > -- Sincerely yours, Mike.