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From: Ignacio Encinas Rubio Subject: Re: [syzbot] [mm?] KCSAN: data-race in try_to_migrate_one / zap_page_range_single To: syzbot+419c4b42acc36c420ad3@syzkaller.appspotmail.com Cc: akpm@linux-foundation.org, hughd@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, linux-kernel-mentees@lists.linux.dev, skhan@linuxfoundation.org References: <67b44eb7.050a0220.173698.004a.GAE@google.com> Content-Language: en-US In-Reply-To: <67b44eb7.050a0220.173698.004a.GAE@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Queue-Id: 8927A4000F X-Rspamd-Server: rspam05 X-Stat-Signature: nxqwz436osj7jec3ww74bs4nhdxsio4j X-HE-Tag: 1742039587-981480 X-HE-Meta: U2FsdGVkX189J2Th7ZcPwLztKAG1dntIEf3klms6U6Esga/v555HW9k8iUiyReDW5F0V8xxmWtNiIv+CTap+Vvxi7Yi/VnVY+2OBGPFANpTOURt1hB3/9w7lJ3tYmJVibI3duVnH2chkz6UqPFEjhe/0xjYkpQx/3a9CdYgSmBtefSttgPMBgW7VMz3VSKghVAz1Zai+If9KfMyUqQip9P+JST8GOunJ6a8jUk7ZhxQqLf6wp4MtHOuxmgmgNL9fuC8uKOLr9CrFvcrGmQsagvtPsLqUeEvOthrHRP53hINUrKtwq5wQnS5NK+3w+ypyYo5iQFwbJ+oZccdxFXf5yu5XfEKkUSACf0yUKrtLJ/xNHc1+oVGcYSmMGI0hlq53lMTR5KOU6lD7JnhIxATeb7ysJZ8oFn9CR3mnX28VuPE3qB9jrXv3QibHUrTIw+yEPrHy9PArp+lgevqNHORSXKb7/GgTObuCkOJL19wSSGbyGWCjmNL308PRTGc9n5UsamKo+h5Sx/OwyTffFVGg0b5QFIH/29LZc5EEX17tScr4zcw2QC8NKhq3YHhw6akDyM9+EyLf0mRWKjOAHSJoLi7ir5nR+kwn9fJWt11NULfn9jG1oIxh39nSO4Zp46GslRNGLAO6TQf178MiMXbE246cJYoIlVZQ6HZ0Scpngzqx6+njHv2jcgdidMtbcmqoIt2jM/jfTaFJbKkKGN6ihqB8l9cP4B60bbRsSohD6J4n5CjxbxsjtJhNDVTGD15Sc05lYqZyB2Ef68nvTGDIs/+aPUSa4eAzBeP0pTaVC6Rhq44PRICtqAvRjSNJ/6/HdyfUi2O/1lV37IqXiQGeVjgwJyS6O05cceMCQdDnlqT979wbq9crP8/00o4HxHK+dtN5U6tF0XV9/DjN3JP3INeptV+tfEZbLM86qq8mZCWSB1CYOkk3ABuBdEyGKBRvH0vUOv7PYzuM6lwX7Gh JBIU/58j rwHJ8/x0y4mjATGmIDUJ8WwQzMoHc8juqFVq1wH/8MkaL7v1hHPup158K5x7f85URjSWE X-Bogosity: Ham, tests=bogofilter, spamicity=0.113201, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hello! This seems like a recurrent complaint from KCSAN (other examples are [1], [2]). >From what I understand looking at the source code, imprecise reporting of the maximum resident set size is considered to be acceptable. Annotating `hiwater_rss` as `__data_racy` [3] should make KCSAN happy. Would this be an acceptable change? Another possibility would be making the update from `update_hiwater_rss` atomic, but it doesn't seem worth the potential slowdown. Let me know if my proposal works for you. Thanks! [1] https://syzkaller.appspot.com/bug?extid=73d65fc86d6338db5990 [2] https://syzkaller.appspot.com/bug?extid=31cd52ba68feee156393 [3] https://docs.kernel.org/dev-tools/kcsan.html#selective-analysis