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b=oGEsB6fbV/dzhN37U1+RQ28sdVXA7PV+Jhd23VCCc+m5vRC4YFVWL63sjPl5Z83UT sHcQuNkGTTugbpeJ6266kYcCVb8QGuK0LQEOzfsKwPsBtzNJWezcytbztyPa1gmuVU FnTYCjFRtbID+jp/GOdlTRMdpbmi04RQdpjF1cgvAQI/zlwGyb5E4RzCzSY9j0DDDW WbM3MsTVHumEgm9UduB1aKyeF1dvNhib7upT+Urp//4wdQ8tZC/Ycb7JeGBIi0bBGO g2W2/yJ2QSAneLThgB8/4GckV6yVcR0IKiphUzjGSnK8jsFXBv4JxKClFa3r933o+e eXabq9uB5ahtA== Date: Thu, 19 Mar 2026 11:12:59 +0000 From: "Lorenzo Stoakes (Oracle)" To: "David Hildenbrand (Arm)" Cc: Lance Yang , syzbot , willy@infradead.org, baolin.wang@linux.alibaba.com, npache@redhat.com, linux-mm@kvack.org, baohua@kernel.org, ryan.roberts@arm.com, syzkaller-bugs@googlegroups.com, dev.jain@arm.com, ziy@nvidia.com, linux-kernel@vger.kernel.org, Liam.Howlett@oracle.com, akpm@linux-foundation.org Subject: Re: [syzbot] [mm?] kernel BUG in collapse_scan_file Message-ID: <024ed30f-db2d-403d-ad3a-3e74a55c6a4a@lucifer.local> References: <69bba3c0.050a0220.227207.002b.GAE@google.com> <10e5f1d6-077d-4783-aa16-6c8b98cb9e74@lucifer.local> <8ab10631-4672-4196-b32e-7c5a01707424@kernel.org> <37b48d94-9576-4529-8576-d4ed615d4768@kernel.org> <5a4fc5ba-ab0b-4294-9577-9b5ee30b2c56@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5a4fc5ba-ab0b-4294-9577-9b5ee30b2c56@kernel.org> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 8B8B21C0010 X-Stat-Signature: ebpm8opdj39iqcir3u6upkfjqmcfkntz X-Rspam-User: X-HE-Tag: 1773918786-32177 X-HE-Meta: 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 RuRjMgSM g4KIw7nAAcC6KtBSJyaBCA0hlfosO+XAnXWXEZndAiSGPkYjlcVGshCzg6q/LuVYQzugVgwg1bfm25lJ0k+T3nmlRegfc6339GrbWAlYR/GPrforitwhFQYXk+SbimpfblgQOiaamRDdEytsZq/7BK6NBpJ4KDZoOETXeXGgf6PyfkZuVaRqE61vL7MMZe12tf9cTkF8xLutAD5qhGvbh3Wrm+m94nUBR3G8oEqvG4liP8gscoxrpV80UD0A4qPp6z7L/9qN3Y4nn1iZQTEBxDM7+gLbZ6icKGS1Bu2hK6Ti+FCzjtpsrBsL1PweZVi9XLc4wmwm6rpDCYTXl6PKO1jVkXgt7Tq773lXygAjluzVMft6gSS3nKLKxHDdFjTaRNFrcQplbC6yGQTKGj75GgOQjKQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Mar 19, 2026 at 12:10:36PM +0100, David Hildenbrand (Arm) wrote: > >> "This isn't the kind of thing where you can just jump in with a one line > >> patch and actually be helpful, sorry." > > > > > > Yup, so again really I don't think the kernel should take the xarray debug patch > > until it is discussed and verified as correct on-list. > > > > See the discussion with Vlastimil. > > Agreed. > > > > >> > >> So I am clueless if there is a real problem there or whether it's just a > >> false positive. And whether (if it's a real problem) the simple fix > >> would actually be a good temporary fix ("make other bugs more likely"). > >> > >> I can try finding some time to look into that, but pagecache code is not > >> particularly the code I'm familiar with ... > > > > I don't think we should waste our time on it, willy's series should be yoinked > > until it can prove itself for-sure well behaved. > > I hear you. At the same time it has the smell of "test case fails, so > let's remove the test case" vibes. > > Well, arguable, it's worse than a test case that fails :( > > I'm fine with dropping that asap. At the same time, I hope we won't lose > our reminder that something possibly bad is broken upstream. I mean hopefully once we have a _working_ version of this it will get reflagged again in any case. The uncertainty makes this worse than a bug report unfortunately because it's a maybe/maybe not and there's literally nothing we can do with that :( > > -- > Cheers, > > David Thanks, Lorenzo