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To: Michal Hocko Cc: Mel Gorman , Mel Gorman , Vlastimil Babka , "linux-mm@kvack.org" , linux-kernel , Andrea Arcangeli , Johannes Weiner References: <20190423071953.GC25106@dhcp22.suse.cz> <04329fea-cd34-4107-d1d4-b2098ebab0ec@suse.cz> <20190701085920.GB2812@suse.de> <80036eed-993d-1d24-7ab6-e495f01b1caa@oracle.com> <20190703094325.GB2737@techsingularity.net> <571d5557-2153-59ea-334b-8636cc1a49c9@oracle.com> <20190704110903.GE5620@dhcp22.suse.cz> From: Mike Kravetz Message-ID: Date: Thu, 4 Jul 2019 08:11:44 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190704110903.GE5620@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9307 signatures=668688 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=962 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907040191 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9307 signatures=668688 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=989 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907040192 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/4/19 4:09 AM, Michal Hocko wrote: > On Wed 03-07-19 16:54:35, Mike Kravetz wrote: >> On 7/3/19 2:43 AM, Mel Gorman wrote: >>> Indeed. I'm getting knocked offline shortly so I didn't give this the >>> time it deserves but it appears that part of this problem is >>> hugetlb-specific when one node is full and can enter into this continual >>> loop due to __GFP_RETRY_MAYFAIL requiring both nr_reclaimed and >>> nr_scanned to be zero. >> >> Yes, I am not aware of any other large order allocations consistently made >> with __GFP_RETRY_MAYFAIL. But, I did not look too closely. Michal believes >> that hugetlb pages allocations should use __GFP_RETRY_MAYFAIL. > > Yes. The argument is that this is controlable by an admin and failures > should be prevented as much as possible. I didn't get to understand > should_continue_reclaim part of the problem but I have a strong feeling > that __GFP_RETRY_MAYFAIL handling at that layer is not correct. What > happens if it is simply removed and we rely only on the retry mechanism > from the page allocator instead? Does the success rate is reduced > considerably? It certainly will be reduced. I 'think' it will be hard to predict how much it will be reduced as this will depend on the state of memory usage and fragmentation at the time of the attempt. I can try to measure this, but I will be a few days due to U.S. holiday. -- Mike Kravetz