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Mon, 24 Nov 2025 18:25:21 +0000 (UTC) Received: from fedora (unknown [10.45.224.27]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 223621800451; Mon, 24 Nov 2025 18:25:18 +0000 (UTC) Received: by fedora (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 24 Nov 2025 19:25:20 +0100 (CET) Date: Mon, 24 Nov 2025 19:25:17 +0100 From: Oleg Nesterov To: Mateusz Guzik Cc: brauner@kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org Subject: Re: [PATCH 2/3] ns: pad refcount Message-ID: References: <20251123063054.3502938-1-mjguzik@gmail.com> <20251123063054.3502938-3-mjguzik@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 19B14180016 X-Stat-Signature: kqwf164igrcf54fyenn1fqcedoisf4rm X-Rspam-User: X-HE-Tag: 1764008726-21197 X-HE-Meta: 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 TEuoqhln N0pF46Z/04k8HvHHzY2groLnBuCW7i5JaE52dsktkUcMAhfWGIzzKpliU1EAtZqBOApvSEWHYwIlmDfT2VVFkgx13svZM28Fr0uicuk//2CF+50fboWpW7rXciCXCCh/QfrkX5R+ZYR7gaYVBm0WlD28D1xT+BPmSIM1z1LsElhoasBeUJLTzk98G1J2G+c6iNoyL/KLl1lz6p7zVkGFp5E0E2JpL5vz9otWXHAfSHTBjdD958SRVI4n217WsMeDBSx8pSSCLTAfmm0ryuBEF10vpystKEVmFA7S6+WbuzdtCuz1YmxKHC977ABaB+/b59H25cyKg9SuAAR6RXdoMWFQ27KoBc1IsvaFMosCe0+LHCqIvy7CxdRGV71pypTzukaxkf5u9nhgy5Vs= 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 11/23, Mateusz Guzik wrote: > > On Sun, Nov 23, 2025 at 7:58 PM Oleg Nesterov wrote: > > > > On 11/23, Mateusz Guzik wrote: > > > > > > struct ns_common { > > > + struct { > > > + refcount_t __ns_ref; /* do not use directly */ > > > + } ____cacheline_aligned_in_smp; > > > > Cough... stupid question. Why not just > > > > refcount_t __ns_ref ____cacheline_aligned_in_smp; > > > > ? why do we need the anonymous struct? > > > > This would merely align the offset of the field, with the rest > directly following. Ah. I didn't bother to read the changelog and misunderstood the intent. OK, thanks. At least I have warned you that my question is stupid ;) Oleg.