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Wed, 1 Apr 2020 16:17:56 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3030.oracle.com with ESMTP id 302g2gwbn7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 01 Apr 2020 16:17:56 +0000 Received: from abhmp0017.oracle.com (abhmp0017.oracle.com [141.146.116.23]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 031GHspi005974; Wed, 1 Apr 2020 16:17:54 GMT Received: from ca-dmjordan1.us.oracle.com (/10.211.9.48) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 01 Apr 2020 09:17:54 -0700 Date: Wed, 1 Apr 2020 12:18:10 -0400 From: Daniel Jordan To: Michal Hocko Cc: Daniel Jordan , David Hildenbrand , Shile Zhang , Andrew Morton , Kirill Tkhai , Pavel Tatashin , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] mm: fix tick timer stall during deferred page init Message-ID: <20200401161810.xvqikca2x46yqrlx@ca-dmjordan1.us.oracle.com> References: <20200311123848.118638-1-shile.zhang@linux.alibaba.com> <20200401154217.GQ22681@dhcp22.suse.cz> <20200401160048.GU22681@dhcp22.suse.cz> <20200401160929.jwekhr24tb44odea@ca-dmjordan1.us.oracle.com> <20200401161243.GW22681@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200401161243.GW22681@dhcp22.suse.cz> User-Agent: NeoMutt/20180716 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9578 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 spamscore=0 mlxscore=0 adultscore=0 phishscore=0 bulkscore=0 suspectscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004010141 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9578 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 phishscore=0 clxscore=1015 malwarescore=0 impostorscore=0 mlxlogscore=999 spamscore=0 mlxscore=0 priorityscore=1501 lowpriorityscore=0 adultscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004010141 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 01, 2020 at 06:12:43PM +0200, Michal Hocko wrote: > On Wed 01-04-20 12:09:29, Daniel Jordan wrote: > > On Wed, Apr 01, 2020 at 06:00:48PM +0200, Michal Hocko wrote: > > > On Wed 01-04-20 17:50:22, David Hildenbrand wrote: > > > > On 01.04.20 17:42, Michal Hocko wrote: > > > > > This needs a double checking but I strongly believe that the lock can be > > > > > simply dropped in this path. > > > > This is what my fix does, it limits the time the resize lock is held. > > Just remove it from the deferred intialization and add a comment that we > deliberately not taking the lock here because abc I think it has to be a little more involved because of the window where interrupts might allocate during deferred init, as Vlastimil pointed out a few years ago when the change was made. I'll explain myself in the changelog.