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smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com; spf=pass smtp.mailfrom=sk.com; arc=none smtp.client-ip=166.125.252.92 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sk.com X-AuditID: a67dfc5b-c2dff70000001609-de-693287767d46 From: Byungchul Park To: linux-kernel@vger.kernel.org Cc: kernel_team@skhynix.com, torvalds@linux-foundation.org, damien.lemoal@opensource.wdc.com, linux-ide@vger.kernel.org, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, will@kernel.org, tglx@linutronix.de, rostedt@goodmis.org, joel@joelfernandes.org, sashal@kernel.org, daniel.vetter@ffwll.ch, duyuyang@gmail.com, johannes.berg@intel.com, tj@kernel.org, tytso@mit.edu, willy@infradead.org, david@fromorbit.com, amir73il@gmail.com, gregkh@linuxfoundation.org, kernel-team@lge.com, linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@kernel.org, minchan@kernel.org, hannes@cmpxchg.org, vdavydov.dev@gmail.com, sj@kernel.org, jglisse@redhat.com, dennis@kernel.org, cl@linux.com, penberg@kernel.org, rientjes@google.com, vbabka@suse.cz, ngupta@vflare.org, linux-block@vger.kernel.org, josef@toxicpanda.com, linux-fsdevel@vger.kernel.org, jack@suse.cz, jlayton@kernel.org, dan.j.williams@intel.com, hch@infradead.org, djwong@kernel.org, dri-devel@lists.freedesktop.org, rodrigosiqueiramelo@gmail.com, melissa.srw@gmail.com, hamohammed.sa@gmail.com, harry.yoo@oracle.com, chris.p.wilson@intel.com, gwan-gyeong.mun@intel.com, max.byungchul.park@gmail.com, boqun.feng@gmail.com, longman@redhat.com, yunseong.kim@ericsson.com, ysk@kzalloc.com, yeoreum.yun@arm.com, netdev@vger.kernel.org, matthew.brost@intel.com, her0gyugyu@gmail.com, corbet@lwn.net, catalin.marinas@arm.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, luto@kernel.org, sumit.semwal@linaro.org, gustavo@padovan.org, christian.koenig@amd.com, andi.shyti@kernel.org, arnd@arndb.de, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org, surenb@google.com, mcgrof@kernel.org, petr.pavlu@suse.com, da.gomez@kernel.org, samitolvanen@google.com, paulmck@kernel.org, frederic@kernel.org, neeraj.upadhyay@kernel.org, joelagnelf@nvidia.com, josh@joshtriplett.org, urezki@gmail.com, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, qiang.zhang@linux.dev, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, chuck.lever@oracle.com, neil@brown.name, okorniev@redhat.com, Dai.Ngo@oracle.com, tom@talpey.com, trondmy@kernel.org, anna@kernel.org, kees@kernel.org, bigeasy@linutronix.de, clrkwllms@kernel.org, mark.rutland@arm.com, ada.coupriediaz@arm.com, kristina.martsenko@arm.com, wangkefeng.wang@huawei.com, broonie@kernel.org, kevin.brodsky@arm.com, dwmw@amazon.co.uk, shakeel.butt@linux.dev, ast@kernel.org, ziy@nvidia.com, yuzhao@google.com, baolin.wang@linux.alibaba.com, usamaarif642@gmail.com, joel.granados@kernel.org, richard.weiyang@gmail.com, geert+renesas@glider.be, tim.c.chen@linux.intel.com, linux@treblig.org, alexander.shishkin@linux.intel.com, lillian@star-ark.net, chenhuacai@kernel.org, francesco@valla.it, guoweikang.kernel@gmail.com, link@vivo.com, jpoimboe@kernel.org, masahiroy@kernel.org, brauner@kernel.org, thomas.weissschuh@linutronix.de, oleg@redhat.com, mjguzik@gmail.com, andrii@kernel.org, wangfushuai@baidu.com, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-i2c@vger.kernel.org, linux-arch@vger.kernel.org, linux-modules@vger.kernel.org, rcu@vger.kernel.org, linux-nfs@vger.kernel.org, linux-rt-devel@lists.linux.dev, 2407018371@qq.com, dakr@kernel.org, miguel.ojeda.sandonis@gmail.com, neilb@ownmail.net, bagasdotme@gmail.com, wsa+renesas@sang-engineering.com, dave.hansen@intel.com, geert@linux-m68k.org, ojeda@kernel.org, alex.gaynor@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org, a.hindborg@kernel.org, aliceryhl@google.com, tmgross@umich.edu, rust-for-linux@vger.kernel.org Subject: [PATCH v18 41/42] SUNRPC: relocate struct rcu_head to the first field of struct rpc_xprt Date: Fri, 5 Dec 2025 16:18:54 +0900 Message-Id: <20251205071855.72743-42-byungchul@sk.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20251205071855.72743-1-byungchul@sk.com> References: <20251205071855.72743-1-byungchul@sk.com> Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; 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\ | ^~~~~~~~~~~~ ./include/linux/rcupdate.h:1047:29: note: in expansion of macro 'kvfree_rcu_arg_2' 1047 | #define kfree_rcu(ptr, rhf) kvfree_rcu_arg_2(ptr, rhf) | ^~~~~~~~~~~~~~~~ net/sunrpc/xprt.c:1856:9: note: in expansion of macro 'kfree_rcu' 1856 | kfree_rcu(xprt, rcu); | ^~~~~~~~~ CC net/kcm/kcmproc.o make[4]: *** [scripts/Makefile.build:203: net/sunrpc/xprt.o] Error 1 Since kfree_rcu() assumes 'offset of struct rcu_head in a rcu-managed struct < 4096', the offest of struct rcu_head in struct rpc_xprt should not exceed 4096 but does, due to the debug information added by DEPT. Relocate struct rcu_head to the first field of struct rpc_xprt from an arbitrary location to avoid the issue and meet the assumption. Reported-by: Yunseong Kim Signed-off-by: Byungchul Park --- include/linux/sunrpc/xprt.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h index f46d1fb8f71a..666e42a17a31 100644 --- a/include/linux/sunrpc/xprt.h +++ b/include/linux/sunrpc/xprt.h @@ -211,6 +211,14 @@ enum xprt_transports { struct rpc_sysfs_xprt; struct rpc_xprt { + /* + * Place struct rcu_head within the first 4096 bytes of struct + * rpc_xprt if sizeof(struct rpc_xprt) > 4096, so that + * kfree_rcu() can simply work assuming that. See the comment + * in kfree_rcu(). + */ + struct rcu_head rcu; + struct kref kref; /* Reference count */ const struct rpc_xprt_ops *ops; /* transport methods */ unsigned int id; /* transport id */ @@ -317,7 +325,6 @@ struct rpc_xprt { #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) struct dentry *debugfs; /* debugfs directory */ #endif - struct rcu_head rcu; const struct xprt_class *xprt_class; struct rpc_sysfs_xprt *xprt_sysfs; bool main; /*mark if this is the 1st transport */ -- 2.17.1