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t=1793614221; bh=PH8c+vUr2qMHZasd7I5mMP2fuKotNi1klsbALagqctg=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=HJyNJIVazbqTzWrUk8kDzEGk/1v20F9z35tlQgMyPWSHtF1GtZdEOIOxdICFB67Bt WQcCYADRA67Clr/QzQO/ZUZplHzRxgNkIXrr7fktyLCmUwqmHfOHM6P1qG1E9aaeY2 YxORbWpenWBvewka4n/rXLv23cFu+m2USUwNrWZ9T/4b+4ePXnwVPxKhfr2PW6cgnr nlZZCjNAvhdNOAhrPJ9cLuGsxvxskE34mCaVEPLt7PsQzrMGAp+F386OCka6qotHaj Tvb0Jm/yE4N9bpRJyC5r56j5F6bYbuVp1tTGSPrLnK8NC6UkbD1F1QeVIpyJ8H11WE qjPnvPiR3cu/Q== Message-ID: Date: Mon, 2 Nov 2026 11:10:16 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/page_alloc: release isolated freepages on compound range mismatch To: Zhenghui Hao , akpm@linux-foundation.org, ziy@nvidia.com Cc: vbabka@kernel.org, surenb@google.com, mhocko@suse.com, brendan.jackman@linux.dev, hannes@cmpxchg.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <5d79db66-2195-4f8d-a721-e1756bc6ead0@kernel.org> 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-Rspam-User: X-Rspamd-Queue-Id: 787B580005 X-Stat-Signature: mx1se3ww6xj9tqy7u7q1fw17y1t3q1ns X-Rspamd-Server: rspam01 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-HE-Tag: 1793614222-822360 X-HE-Meta: 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 bYsTuc9G In1zDrUrWIUD/kmbawW9pe+RTXQktiJH3lL5TPLCQwHI4gCa3zcF4srEPFYOCRe+Hm5jwxCb2cMIdagcyffeQ6Nd5m+2EzO0e+am0ZfBmRQHEvadoqFSmjKqAYg0TMa6z8kJn+EUUA5ZA9RPQvXFKaHgYUYJyX8M/9Om6bV3xgP7jNl7KqSw1CRP6aNSp+91E3HzsPsceuDBB6SrfKmeI5t2ubmTvoja0+mZcyYSgS5ly2Ho+/M1fJAHCA340YOlsKkqP6kLCGpl81LUaEbzYtDD7TtVa8XOeYED+vkWy3ePzlrZTZhdRb8IJcNrZ0t0wox9e3oBlq6cvKQiU2pTotzhg40exH0bsp7bF 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 11/2/26 10:29, Zhenghui Hao wrote: > > On 2026/11/2 17:11, David Hildenbrand (Arm) wrote: >> On 11/2/26 10:06, Zhenghui Hao wrote: >>> alloc_contig_frozen_range_noprof() isolates [outer_start, outer_end) >>> before checking whether a __GFP_COMP request exactly matches the >>> allocated range. If it does not, the function returns -EINVAL without >>> releasing cc.freepages, leaking the isolated pages. >>> >>> Call release_free_list() before returning -EINVAL, while the pageblock >>> is still isolated, matching the cleanup already used when >>> isolate_freepages_range() fails. >>> >>> Use WARN_ONCE() as well: the condition is reachable through the exported >>> API, and repeated invalid calls should not flood dmesg. >>> >>> Tested with an order-9 free pageblock and a one-page __GFP_COMP >>> subrange: >>> before: free_buddy=0, leaked=512/512 >>> after: free_buddy=1, leaked=0/512 >> How did you reproduce this? Using a hacky kernel module? >> >>> Fixes: e98337d11bbdf ("mm/contig_alloc: support __GFP_COMP") >> I thought we discussed this in the past: if you are able to trigger the WARN >> something is messed up already. >> >> >> And indeed, same patch already here, SMH >> >> https://lore.kernel.org/linux-mm/20260629-free-pfn-on-alloc-contig-range-error-path-v1-1-496ff9ca22db@nvidia.com/ > Thanks for the pointer, and sorry for the duplicate -- I missed the > earlier thread. > > You're right on both points: the reproducer was a synthetic module, not a > real workload, and being able to trigger the WARN means the underlying > path or validation needs fixing rather than papering over it with > WARN_ONCE. > > I'll drop this version and follow the existing thread. I'll check whether > the earlier patch is still pending and only send an update if there is a > real delta on the current tree. @Zi, are you still intending to follow up on the things we discussed in that thread? -- Cheers, David