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AJvYcCVMhYL5koXln4IaVvKHrl7PoAVFQY1iOq3TzFne0VDv7ywia1yS7OThwyFr8ZwcT1tH5w0SDAkoGg==@kvack.org X-Gm-Message-State: AOJu0Ywr2rhB46dwRp94WEyiqjtVPQj8IpiAMR5s3surTTu1cTV9TR0x teeu7zM8u+ggs9Q54OHIaAiiUrmbTCd76Deo/Q5mGvH0Zn9RI8nOa4rVHe19ZiN02AjLlFi+US+ TwJQY3gNEow0gfmr4QWc2I7OgK+HAXNa7chL6U60U X-Gm-Gg: ASbGncsjdCpLaj3L1eRW/wxpYSQyn9DUIoni0fuowdjgRAKXSIHBD0iLW+mwkkPrA8w zbufAoeDUl1WX6XJjfDcyNDC1OOQJWrKSoyGWwGgqJBfLnb2qRJ7DIVNzmlMvn+4HPOW7KkYEV3 mIqx0NQ8HqY9ezaRGmfVx/MYZbDlH145T/Y5kpAGnobvR6+2KvlSy85SitdVMkrMWfRiSRYL+hY x4i6vRZPCEUpfEAROSuxf/jkm4+z5quj/2N59GCfcYq X-Google-Smtp-Source: AGHT+IGEb9fQVFGlEJXvdZv7glWzKfh9yb2g3ypJs/1z3YlFmIJ1fCW1zhKyPJig4x9nGqaEce6mvh0neogmq1REEMo= X-Received: by 2002:a05:600c:4927:b0:45f:5b02:b0cb with SMTP id 5b1f17b1804b1-46149490f52mr1528735e9.0.1758137578779; Wed, 17 Sep 2025 12:32:58 -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 12:32:47 -0700 X-Gm-Features: AS18NWA8ltNJ-1yAPEykUi8kpppNk1zprgJjx3ovrdKhQKA72C47t087_EGFCP8 Message-ID: Subject: Re: [PATCH v2] mm/memory-failure: Support disabling soft offline for HugeTLB pages To: David Hildenbrand , Kyle Meyer Cc: Anshuman Khandual , akpm@linux-foundation.org, corbet@lwn.net, linmiaohe@huawei.com, shuah@kernel.org, tony.luck@intel.com, 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-Stat-Signature: 1cgwdsxyitqabgym7jyt69qom7cyi67b X-Rspam-User: X-Rspamd-Queue-Id: 8A92F18000A X-Rspamd-Server: rspam10 X-HE-Tag: 1758137580-645260 X-HE-Meta: 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 2klQKjmg 93wwxg3ycgMuocoI= 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 12:05=E2=80=AFPM David Hildenbrand wrote: > > On 17.09.25 20:51, Kyle Meyer wrote: > > On Wed, Sep 17, 2025 at 09:02:55AM +0200, David Hildenbrand wrote: > >> > >>>> + > >>>> + 0 - Enable soft offline > >>>> + 1 - Disable soft offline for HugeTLB pages > >>>> + > >>>> +Supported values:: > >>>> + > >>>> + 0 - Soft offline is disabled > >>>> + 1 - Soft offline is enabled > >>>> + 3 - Soft offline is enabled (disabled for HugeTLB pages) > >>> > >>> This looks very adhoc even though existing behavior is preserved. > >>> > >>> - Are HugeTLB pages the only page types to be considered ? > >>> - How the remaining bits here are going to be used later ? > >>> > >> > >> What I proposed (that could be better documented here) is that all oth= er > >> bits except the first one will be a disable mask when bit 0 is set. > >> > >> 2 - ... but yet disabled for hugetlb > >> 4 - ... but yet disabled for $WHATEVER > >> 8 - ... but yet disabled for $WHATEVERELSE > >> > >>> Also without a bit-wise usage roadmap, is not changing a procfs > >>> interface (ABI) bit problematic ? > >> > >> For now we failed setting it to values that are neither 0 or 1, IIUC > >> set_enable_soft_offline() correctly? > > > > Yes, -EINVAL will be returned. > > > >> So there should not be any problem, or which scenario do you have in m= ind? > > > > Here's an alternative approach. > > > > Do not modify the existing sysctl parameter: > > > > /proc/sys/vm/enable_soft_offline > > > > 0 - Soft offline is disabled > > 1 - Soft offline is enabled > > > > Instead, introduce a new sysctl parameter: > > > > /proc/sys/vm/enable_soft_offline_hugetlb > > > > 0 - Soft offline is disabled for HugeTLB pages > > 1 - Soft offline is enabled for HugeTLB pages > > > > and note in documentation that this setting only takes effect if > > enable_soft_offline is enabled. > > > > Anshuman (and David), would you prefer this? > > Hmm, at least I don't particularly like that. For each new exception we +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. > > -- > Cheers > > David / dhildenb >