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b=lFzKRkRAagp0TVhUdTwIsW0EPgf7xwe5vUnZsgItAsbqWLbYcv7v2Q3oCdo6pdbpH TxK4cHFxGzDDbQDQTmmTAALXtRce7awXslf/w51ZRllOlHQfykkv/S85tSAEJm9jFJ GYwvA6uugwAlC/eFWM7ehADw13/t37TYV5luOUQD7lDrfqGG54YTKnaTyEWvTdRb0c orc+Nn8y24EKqDs+XjojdkthXLkOB/CpwUkMKq+3hkvcz1Knd27dZO22vw3HIZH/oz KeJJqGDMye/t+diEqfyZzsugo6eKkklnr+1Zd5LuUfHG/pa69kR/h1070kPLMeXwGn kaCdIbmTIMmYw== Date: Fri, 3 Oct 2025 12:33:03 +0100 From: Mark Brown To: Byungchul Park Cc: linux-kernel@vger.kernel.org, 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, dave.hansen@linux.intel.com, 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, 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 Subject: Re: [PATCH v17 09/47] arm64, dept: add support CONFIG_ARCH_HAS_DEPT_SUPPORT to arm64 Message-ID: References: <20251002081247.51255-1-byungchul@sk.com> <20251002081247.51255-10-byungchul@sk.com> <20251003014641.GF75385@system.software.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="CPEOfhRT6FsWLRqF" Content-Disposition: inline In-Reply-To: <20251003014641.GF75385@system.software.com> X-Cookie: hangover, n.: X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 23655120004 X-Stat-Signature: js4ba68j8ge3eyqkhrsr739q5aiqborx X-HE-Tag: 1759491220-356781 X-HE-Meta: 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 7XEKuPa0 UzYhRGjcfOc0gqXbC8IkCt78BLXU6yYhw9hOqoeQgwPHeDL7mqJx0NwKx++RBLxLW+kUKz9ECF7K7H9mqtqE0fUnvvSBDeB7hTfvUwYlsdeZkX82J0OQZJG/H8fkM/3StzQwRbAIU1XAzIvS8xCN4Bhsw+xX0uiwFlDnIXwDUxapTdsC+wARxVevr6FD23A6LHbcSap7BirWnduk9WkotAbkA/f+lrWY5D95FMNKLal5LJv/vkvSZ0yEEIQW2kZWeIk3cZlRzV6wopSKtBsiVDv9D1jWo/zFlG+tnrkv5hhK6yLs985/OCAVZWJDSrF91lMhPlZ5/urt/lA8vyXoaFvts2EFJ8YK3bqT/mrYeE96FFtdBX6DNvpJjj2yvtjBhM36Oa8X6rSelLxSzYKR2oYTom4VpeLWNqoG/njNS+3SeGpxHk7hUXXATbtcfMa9GKGVlVAqKZTHNeqXUyq5gSU+4uvuYFFhXTqypl+Dwrbw9UWE= 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: --CPEOfhRT6FsWLRqF Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Oct 03, 2025 at 10:46:41AM +0900, Byungchul Park wrote: > On Thu, Oct 02, 2025 at 12:39:31PM +0100, Mark Brown wrote: > > On Thu, Oct 02, 2025 at 05:12:09PM +0900, Byungchul Park wrote: > > > dept needs to notice every entrance from user to kernel mode to treat > > > every kernel context independently when tracking wait-event dependenc= ies. > > > Roughly, system call and user oriented fault are the cases. > > > Make dept aware of the entrances of arm64 and add support > > > CONFIG_ARCH_HAS_DEPT_SUPPORT to arm64. > > The description of what needs to be tracked probably needs some > > tightening up here, it's not clear to me for example why exceptions for > > mops or the vector extensions aren't included here, or what the > > distinction is with error faults like BTI or GCS not being tracked? > Thanks for the feedback but I'm afraid I don't get you. Can you explain > in more detail with example? Your commit log says we need to track every entrance from user mode to kernel mode but the code only adds tracking to syscalls and some memory faults. The exception types listed above (and some others) also result in entries to the kernel from userspace. > JFYI, pairs of wait and its event need to be tracked to see if each > event can be prevented from being reachable by other waits like: > context X context Y >=20 > lock L > ... > initiate event A context start toward event A > ... ... > wait A // wait for event A and lock L // wait for unlock L and > // prevent unlock L // prevent event A > ... ... > unlock L unlock L > ... > event A > I meant things like this need to be tracked. I don't think that's at all clear from the above context, and the handling for some of the above exception types (eg, the vector extensions) includes taking locks. --CPEOfhRT6FsWLRqF Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmjftG4ACgkQJNaLcl1U h9AJAwf9GUZ8nquWa7D1no47c5NWSm5cMwwvmTjDaPtYC52seNgxT47rqiAa032b rbQuOcdIvbMOoRrk3oOjch4rbo2VSgw1bzxKncoUyWrQ1rw9rhdfmdQpZZSbT1XQ ZE3VcLNDV3bfjO2GU8cTjiUDwM29qIeTSzCIn9ubfHcuEvoaYes1/BrQYAwB6ghQ 7LjwZANFGJdatftOLPlVL8kKM/B5H6eSUlr8bUS9hlZE2g39/1LLb9UexVvnMj8u 6gPRXHiHF5Vzad2FqVmWKt4F1F39CJ4g1c624zJiIGAWP9iBONB8dIyQPlTmK4U7 mnXQy7USXtlxU+Xw5RCO9fy5x0Ahxw== =LMdg -----END PGP SIGNATURE----- --CPEOfhRT6FsWLRqF--