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b=Ppjq6ucixIquylI1RXa0glpRlIx0VRokubeu3+Rd9Zd3zOXS9VnLl/cf7El20ued2 LHGK6Xk9IQaRqA1ZpE5lW55bE8uTquQAGIOd9nbpx+msITLI5rBfXXBi6zLH41Zeqc PQVQTbbhTl+Xu3JKPXDUPG5SFtltCsZNT5zDz5R5fMPIh9kI/s6nMR6wCLH/WBSttZ Jd5uHYmnCRco+nGQQ0WjggVO4uKe9cQrI20/3HnGRX8jkvjhI3JLTfX7mJMkM07Cdu F2b+fzMNBq2vYgLkkqQ8IJadCUPcQEYgH5F/oqVQGjN5I00CKnmk+1zKvUPVkVo3LC m4OYLuMKXTIMQ== Message-ID: <5e980194-d892-4b68-80fe-612c910c29d7@kernel.org> Date: Wed, 28 Oct 2026 09:37:39 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 0/8] mm: fix allocator races with memory hotplug To: "Gregory Price (Meta)" , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, kernel-team@meta.com, akpm@linux-foundation.org, mhocko@suse.com, rientjes@google.com, shakeel.butt@linux.dev, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, muchun.song@linux.dev, osalvador@suse.de, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, brendan.jackman@linux.dev, hannes@cmpxchg.org, ziy@nvidia.com, bigeasy@linutronix.de, clrkwllms@kernel.org, mgorman@techsingularity.net, anshuman.khandual@arm.com, Bessel.Wang@huawei.com, jiang.liu@huawei.com References: <20261021023940.1940971-1-gourry@gourry.net> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: D06F0C0005 X-Stat-Signature: n7meqajsn946ecxbphjphfohnr8q1e8r X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1793176669-357116 X-HE-Meta: U2FsdGVkX19o6QJZuU+rL5SB2cQ90Y80toI042bEiTgyXeMK82wIrExZgVK2f/ogMCfSvlV+zwMB/kkLnfNlqrTMALo48pRefBphmlN7MjPkbAlAmOlA5ThYFmXL2+hABZWnjOVkxQSp0DujwEnOTiwAPE4Z5S9phQDHY7zHNfyfz66WXs9aK8cHIbjwzzIMF/OArQJnIkQUfxkVJrUfND2HyL4wYOT5xERej+1ObyF4/1Kb4Ov9thZPDhX8Snwh8LI9uwKnsTiytfGmV+HkhZcrVnofo+93ba9eEDO3amkxOoAThVFMqHxUGesA038Qofp1+g+D4yRAiOwuti9Bexj7sNUaYl4RT8J6X/RZW/lDTGxS1xWfJT/p/IgPM5MUxxJXzzNDlOBNnF/QNPvxZjLU5NpELFhdJMXEzQmkTDF0Uvu/fn/WdsHycq/ooVDMwTz5+w01K9rCppuVmds38yYkZen88RPJgzZ8/8WWfu7ADqUlJ8VGlCd5y6n+zYLxbbz5rRfwfa6aR3WYOAy020Qz6LXt+T/5+XmV68N7NAfsoyzs/QA/IHu0isi1tWHhqRI0jvfifmgSVZrq4eKpmYn0ygeP5PWAZ61ocW9nJX+HAVF3KFn/96P6KC925GfXF6vbCaRPwPsbpaXatrqWzEGti5kpSu7CgxMIX8TUALU0DMVBlgbg0CDPmXW+9N2RLFu/hb8cezFUap0rIbM5gThonVYyi+cWiqM1+uVU2HQCGynUd4G+5BYlQC/V6pVMnwCp8Ix1ojlYhZ0aA3iuwE9GhimjQW5eYN7ThfHboeBkq9lxwvuV38SYniVjlfjOzPktCpc6gE81vOZ8CfDpXI+f2h13LWEfgQcnKuyeA/hACzl1l9H3SD7E7MYFl6NTNO0oTHvnkH835b8KKbSNTRVojv5N1QbPHYKGj8FNvpAS1LqBDToDqWxLmWA1szozYdq3ekiCmIrBAQyJNwu 9qOEHV69 /011Kw8QRa1TVI2xgkm03yY86hcrKob1Ue25zGWdrnGSw3cDp+n0XGZluXjT+i3YMhb6oAGAmdmOFaBvBX4SiXKLWZ9yCZc+wD5oe2VItxHLxWhndDE7GWoXP7gCuvZEPc196CfqvObau0Ldt6aPybl6KdWcZgA2Vmd7CqVRk0c4dSfhSmigdN1RoEcWFxg2TuKYGq98qwxC/M0r7GLbd3WnMX3maRhVJrs521RT0DZzYs0zLJBwXYSAppn2FpAj1xeLpV8FiZcHLDhUXWUp/uD6m6GLmiGTQCcredJM3qpnFSEU1fJBCF22JnakQ0dkT/pOqumvTHWp4GPY= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 10/21/26 04:39, Gregory Price (Meta) wrote: > Eight fixes for allocator paths that can act on state another CPU is > updating: zonelists rebuilt by memory hotplug, and the pagesets of a > zone that offlining empties. > > I've packaged these together because they're all related to hotplug. > > *** Backport note - Patches 5-7 build on patch 1: without it, their > retry is compiled out when CONFIG_MEMORY_HOTREMOVE=n. > > Most of these race conditions stem from zonelists being re-ordered > in-place at runtime during hotplug. The result is a mixture of failed > allocations, NULL dereferences, incorrect placement (GFP_KERNEL in > ZONE_MOVABLE), node misplacement, or incorrectly allowing hugetlb / > contig allocations on a node/zone otherwise not eligible. > > Most of these are incredibly narrow race conditions, but since the most > likely impacted machines are VMs with memory hotplug, the narrow > condition can more easily occur when a vCPU takes a long interrupt / VM > exit of some kind. I've made all of these race conditions > deterministics with a kprobe reproduction module described below. What's the status of this? "memory hotplug" caught my attention, but then then is all page_alloc material :) -- Cheers, David