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AJvYcCVBmfxbJPznD2qiDsFTo6KL134Mu6onAa647/sOXcDltu86etft/GUP/GhGcwLarj6Gbx/AtfJkDQ==@kvack.org X-Gm-Message-State: AOJu0Ywk0mUahsMr8Sf2pgEnx7nXgU558UK5R2fKaSwKOUsaJK/lrYXV g6bLSaVknn0Pz3GKWFiDwoFdJlOA7uv9lLiMlxuTHN+jGaC9+SFO4L2VB6SqsP60NPpn+h6XU+b So0AnEa4WV0Lv61sZsqCa+Vup5m//8wky1Ehkq4nb X-Gm-Gg: ASbGncttVUrd07+E/hGqQXt0AEPiIrh3k9hrOIC4O04evWUYcWl5aLg9tiTBtPhw9dJ 41xU/AlEfy2ANSYE0Y5c2u3/ym/Dz7mx58slXCgGMJx9R+VtqtRq2DkrlIlcBDM8QbjLgTLL2o1 WBB79RQ5QmxR65u4wrhz8Tdhim6862oCRbLhjLlaIcgYneT3+pIlCz3b1vfKbiOxNZI+kwghWQ4 5FDiuMPr8ojsQI/lGPS24hD0p8km6cABvU60aHyoo4eRsAOPbdj+7YqyDhHM7Y= X-Google-Smtp-Source: AGHT+IETa168RMgXYCyuMbREDGOaHVmJadjLDpn2kmhrTSuNtoIw5sYpaUJCBGdkIQavpq6g1JLeI6FZ1TdA3bdskYU= X-Received: by 2002:a05:600c:3f0e:b0:45f:2e6d:c9ee with SMTP id 5b1f17b1804b1-4615364d0efmr2582795e9.6.1758147352822; Wed, 17 Sep 2025 15:15:52 -0700 (PDT) MIME-Version: 1.0 References: <8c3188da-7078-4099-973a-1d0d74db2720@redhat.com> In-Reply-To: From: Jiaqi Yan Date: Wed, 17 Sep 2025 15:15:41 -0700 X-Gm-Features: AS18NWB0Be2bZgwB40bum70rJy1DrSew59KlnBWueOxwtEk5FxFH7XCa5Jb7Kdo Message-ID: Subject: Re: [PATCH v2] mm/memory-failure: Support disabling soft offline for HugeTLB pages To: Kyle Meyer Cc: "Luck, Tony" , David Hildenbrand , Anshuman Khandual , akpm@linux-foundation.org, corbet@lwn.net, linmiaohe@huawei.com, shuah@kernel.org, jane.chu@oracle.com, Liam.Howlett@oracle.com, bp@alien8.de, hannes@cmpxchg.org, jack@suse.cz, joel.granados@kernel.org, laoar.shao@gmail.com, lorenzo.stoakes@oracle.com, mclapinski@google.com, mhocko@suse.com, nao.horiguchi@gmail.com, osalvador@suse.de, rafael.j.wysocki@intel.com, rppt@kernel.org, russ.anderson@hpe.com, shawn.fan@intel.com, surenb@google.com, vbabka@suse.cz, linux-acpi@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 8FFBB1A000D X-Stat-Signature: rqxyobmjcefrstpooiqj1ajexj6p3qxg X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1758147354-958818 X-HE-Meta: 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 KMNU8K1B u+RcBl2nI9CKDi9R8HTvyC+w3dEocCVAdffqPAUqFUC1fcFJGdgPBzUigKFcJ1lY6SSAIDNk4K2UsJgadmEMKaHz5tbRk37+w/HLYagfi/rDUjpKqlvhHqGC4JvBEe/z1CufQSZdaeGnLTkY+CZ23a5XrUlT4+FuSRoMYsiZsr/FzgmeS0XsianMVp0eeXwMb9ztzuQWaj3aR7/cdzTfo2IXk/VX+vBLi2Oub6CgFzAvHx3KjOJ7SnH0/50xFxtOqj/afKDlkIgJgvAHq7qFGG4/Hlf9eFLFsSRQO X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Sep 17, 2025 at 2:39=E2=80=AFPM Kyle Meyer wro= te: > > On Wed, Sep 17, 2025 at 12:54:09PM -0700, Luck, Tony wrote: > > On Wed, Sep 17, 2025 at 12:32:47PM -0700, Jiaqi Yan wrote: > > > +1. Given /proc/sys/vm/enable_soft_offline is extensible, I would > > > prefer a compact userspace API. > > > > > > > would create a new file, and the file has weird semantics such that= it > > > > has no meaning when enable_soft_offline=3D0. > > > > So the expand the bitmask idea from earlier in this thread? > > > > Bit0 0 =3D soft offline disabled. 1 =3D Enabled (but see other bits) > > Bit1 0 =3D allow offline of 4K pages, 1 =3D suppress 4K offline > > Bit2 0 =3D allow offline of hugetlb, 1 =3D suppress hugetlb offline > > Bit3 0 =3D allow breakup of transparent huge pages to just offline 4K,= 1 =3D suppress transparent breakup > > Bit4+ Reserved for suppressing other page types we invent in the future > > > > Values 0 and 1 keep their original meaning. > > > > Value 5 means: offline 4K, keep hugetlb, breakup transparent huge pages= . > > Do you happen to have any use cases or reasoning for why someone might wa= nt > to disable soft offline for 4K pages or transparent huge pages? I'd like = to > understand the motivation for adding the extra bits. Not sure if making sense, but something I can think of are: one may really not want performance impact as THP will be split, THP and 4K pages will be migrated, and even wildly willing to defragment with 4K pages with corrected errors? > > Thanks, > Kyle Meyer