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b=HA/tmooAm7H0WnStcyUYwNwCrxEXDDjkCXD8RRMBEBxkJmTWFMu9+AXrRydUGHzU1 DSdPbQJ0TMVDvsj4SHJBuCZvEOLxbj4HNdamPG5v9/aOnwqxKrwRph4/HY1P7xSSkm dfY8bLps097wtInJHSQhc/5nmZ67k9zwObuphCTg= Date: Wed, 1 Apr 2026 17:44:40 -0700 From: Andrew Morton To: Anthony Yznaga Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, david@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, jannh@google.com, pfalcato@suse.de, Jason@zx2c4.com, shuah@kernel.org Subject: Re: [PATCH 1/2] mm: fix mmap errno value when MAP_DROPPABLE is not supported Message-Id: <20260401174440.0f85ea303f0a027b50d99e5d@linux-foundation.org> In-Reply-To: <20260402003417.438037-2-anthony.yznaga@oracle.com> References: <20260402003417.438037-1-anthony.yznaga@oracle.com> <20260402003417.438037-2-anthony.yznaga@oracle.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: 6j3ciowy55e3me7oeaggkrun9xaqsbtj X-Rspamd-Queue-Id: 3D00540013 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1775090683-162951 X-HE-Meta: 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 Gv2aPiW5 gKZdZXzOmNmP5tFRN32eiQVNFwYElttp0gNksJWBSbTUOTBN391G/VUs8agdmB4bQd4+SHObwtPosOw0bUMwHVYIx/rL55rUWP/e9KEJpbv38TDcZSycQFw/1t+GvTGw0dmcKGAM5JX70cdy9Lxe8hyd3BxQdgOfzTFZ/3L7FtIs/wNQn1pDBlMAV+qBdLKA6qBfZ9bvNWsYOtW+br71/kyJMer8Jy8xHfe0IEwS8q5oA+zA0/MFSUadM1hpGCgtVvngXG8LhGAqodIuUbFOOCA83Nv28Pu+/smKdzDfnk2ZMqMFfibqNCIpK593g5vWYSuLk Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 1 Apr 2026 17:34:16 -0700 Anthony Yznaga wrote: > On configs where MAP_DROPPABLE is not supported (currently any 32-bit > config except for PPC32), mmap fails with errno set to ENOTSUPP. > However, ENOTSUPP is not a standard error value that userspace knows > about. The acceptable userspace-visible errno to use is EOPNOTSUPP. > checkpatch.pl has a warning to this affect. Sounds very reasonable. EOPNOTSUPP is clearly a networking thing so what on earth is it doing coming out of mmap code? Our poor operator is now looking at a networking error code and wondering what this supposedly non-networking application is up to. But just that's a pet peeve - I lost that one decades ago. > Fixes: 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always lazily freeable mappings") Nearly two years ago so I think I'll add this to mm-unstable for 7.1-rc1 and shall let it trickle back a little more slowly than might a 7.0-rcX hotfix.