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Tue, 15 Sep 2026 17:55:06 +0000 (UTC) Date: Tue, 15 Sep 2026 12:55:03 -0500 From: Kyle Meyer To: Michal Hocko Cc: akpm@linux-foundation.org, corbet@lwn.net, david@redhat.com, linmiaohe@huawei.com, shuah@kernel.org, tony.luck@intel.com, jane.chu@oracle.com, jiaqiyan@google.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, 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 Subject: Re: [PATCH v3] mm/memory-failure: Support disabling soft offline for HugeTLB pages Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Proofpoint-ORIG-GUID: ZGyhASJQPrkZtald6s-qe-XaJzb3rLwu X-Authority-Analysis: v=2.4 cv=SJ3Xx+vH c=1 sm=1 tr=0 ts=6aa98681 cx=c_pps a=5jkVtQsCUlC8zk5UhkBgHg==:117 a=5jkVtQsCUlC8zk5UhkBgHg==:17 a=kj9zAlcOel0A:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=gQcMVamqm3wCPoSYhaRC:22 a=_ZmgHqWwjZUDpi_pur5s:22 a=VwQbUJbxAAAA:8 a=MvuuwTCpAAAA:8 a=OCHxr62PC90mTwIpeikA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTE1MDI2MCBTYWx0ZWRfX/bF3jfMe5L2R j63mU1nIBKQUtxaBXijRxEhjpUkMVc4zIvOsjeAo1gXa6d8EaQ3zY67L76NuqyOpj1PqfHtArmO 2vl0Zj/ywj1xKqs1a/mzZMNwlkOXYrqejAwJQ505r93PdMuHej9YKGoy+OOhjdgIGcbnHU5kPaU yvvrSCWy5ejLgHtdaE3GjSon0dkRbhoyLPGlPM5ivm10iaII7ndWeW/6v4Wb+WicsOGN6iGbq5y TmACnEazHYCmP+PBiUKK1AlL2cSjGIx6qbmqEPScHv5nRJqfghhw+WYCVTjioKj934H6QVwbEyn +l7ofYSeMOrVz1JhspzsrFr1N4lD/2CI+O885v1QKv5nzT3CrROQPCxW5DGn1rcxZV1AAEnv7EB 8HBx6GOAVf7DeSMdD7b3ATQFGeRAgDSkWYdpFHxj64RkQev4NJH17HwCiED+iffIRQ5Flebq0JV zWia0hniMaXW7l/WWHg== X-Proofpoint-Spam-Info: AW1haW4tMjYwOTE1MDI2MCBTYWx0ZWRfX63h0+WaHo6KX o28u0TT4xIFnPPwvxBVPnt73ZCm6PXqMR4K+TANuw3CaFV5L9FIl2AQlI4GVDKvAEj81K9dRKGJ DaYbaSq0UXlb+dnZCcP9Cbxr0DS1x+w= X-Proofpoint-GUID: ZGyhASJQPrkZtald6s-qe-XaJzb3rLwu X-HPE-SCL: -1 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-15_05,2026-09-15_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 priorityscore=1501 phishscore=0 adultscore=0 bulkscore=0 clxscore=1015 lowpriorityscore=0 malwarescore=0 spamscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609150260 X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: A3C1318000C X-Stat-Signature: zmg865p99yqxonuuejqjnfex3x7r9w78 X-HE-Tag: 1789494953-644716 X-HE-Meta: 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 G+6QB9Z7 aFKhdOHBROr5Ss89w6EL8rKwmHZJLI6TDEnQe3FfL3lvM1zI1/gFjrSumgl+7dZdyNuI7NEuKkJZo2L4RK/rOyWLT5p6g+5JhxZ6S9pgvBIxmD/dCR/Tu2TQjkppiktmYVdJGRKEbynGqSLqS3FrmY2Rt7QPmMwP/2eId1fghN13S76LWDGLruucaIdjaDHHrMoM0tlZMUUWFpQdCVFnKLuKKaXXBmCXREWwc4WCVJY1XCJFfF1Psa0yTSaAzTvc2YAhtXALA7qK8NO5Gilk+wylVOnm5rptwICPz Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Sep 15, 2026 at 10:31:42AM +0200, Michal Hocko wrote: > On Mon 14-09-26 18:49:38, Kyle Meyer wrote: > > Soft offlining a HugeTLB page dissolves it, permanently reducing the > > HugeTLB page pool. This can be problematic for workloads that depend on > > a fixed number of HugeTLB pages. > > > > Currently, soft offline must be disabled to prevent HugeTLB pages from > > being soft offlined. > > > > This patch allows soft offline to be disabled for HugeTLB pages while > > remaining enabled for non-HugeTLB pages. > > > > Commit 56374430c5dfc ("mm/memory-failure: userspace controls > > soft-offlining pages") introduced the following sysctl interface to > > control soft offline: > > > > /proc/sys/vm/enable_soft_offline > > > > The interface does not distinguish between page types: > > > > 0 - Soft offline is disabled > > 1 - Soft offline is enabled > > > > Convert enable_soft_offline to a bitmask and support disabling soft > > offline for HugeTLB pages: > > > > Bits: > > > > 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) > > > > Existing behavior is preserved. > > > > Update documentation and HugeTLB soft offline selftests. > > This is adding a lot of user interfaces to control something you can > disable by config option for an admin only functionality. I may be missing it, but I'm not aware of a config option that disables soft offline specifically for HugeTLB pages. > I fail to to see any actual justification for all of that. If an admin > can disolve a hugetlb page it has power to allocate a new one as well. Allocating HugeTLB pages after boot is not guaranteed. > Not to menation that the whole soft offlining is mostly a testing > feature so adding a lot of fine grained configuration space seems > excessive to me. Can you elaborate on "mostly a testing feature"? For example, how does that apply to the BIOS/GHES path discussed here? https://lore.kernel.org/all/aMkOCmGBhZKhKPrI@hpe.com If you think this should be handled differently, I'm open to suggestions. Thanks for the feedback, Kyle Meyer