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Fri, 13 Dec 2024 10:37:27 -0800 (PST) MIME-Version: 1.0 References: <20241211082541.GQ21636@noisy.programming.kicks-ass.net> <20241212091659.GU21636@noisy.programming.kicks-ass.net> <20241213095729.GC2484@noisy.programming.kicks-ass.net> <20241213183546.GB12338@noisy.programming.kicks-ass.net> In-Reply-To: <20241213183546.GB12338@noisy.programming.kicks-ass.net> From: Suren Baghdasaryan Date: Fri, 13 Dec 2024 10:37:16 -0800 Message-ID: Subject: Re: [PATCH 3/4] mm: replace rw_semaphore with atomic_t in vma_lock To: Peter Zijlstra Cc: Matthew Wilcox , akpm@linux-foundation.org, liam.howlett@oracle.com, lorenzo.stoakes@oracle.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mjguzik@gmail.com, oliver.sang@intel.com, mgorman@techsingularity.net, david@redhat.com, peterx@redhat.com, oleg@redhat.com, dave@stgolabs.net, paulmck@kernel.org, brauner@kernel.org, dhowells@redhat.com, hdanton@sina.com, hughd@google.com, minchan@google.com, jannh@google.com, shakeel.butt@linux.dev, souravpanda@google.com, pasha.tatashin@soleen.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: C66491A000D X-Stat-Signature: x99tftip195ddykq8yw7yagfues3txka X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1734115020-191349 X-HE-Meta: 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 gRM6qSDB tUeQca1FXq2rNHIPifaylCk4LNn1AAtTZrmOmnur8/sLl/mPeG5M5N9I8llDoG+eKdFNECgjyU5m6z38njDRiTh9SWYdkBXRLSpdboCQJmMh2JVhEFrGQfOoSXCY0u+OJN/vo/OPOl1Aytdg8MN7dAvkPDx8rdJDqaNJ6Zbh4h+41AOyll16zJj0+fbTtQ/ADDDUC1p9sF/jyVGCXDaIS+ZkItsqBwI00NIYuNkE/T0iWty5otNRnWHEVbb+wBdUnbLOx81ZRpRn1hU4nWjeO4XCGtCb6HKk7dDTe2lgFIJvqf+U= X-Bogosity: Ham, tests=bogofilter, spamicity=0.282759, 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 Fri, Dec 13, 2024 at 10:35=E2=80=AFAM Peter Zijlstra wrote: > > On Fri, Dec 13, 2024 at 09:45:33AM -0800, Suren Baghdasaryan wrote: > > On Fri, Dec 13, 2024 at 1:57=E2=80=AFAM Peter Zijlstra wrote: > > > > > > On Thu, Dec 12, 2024 at 08:48:52PM -0800, Suren Baghdasaryan wrote: > > > > > > > I'm not sure if this is the best way to deal with this circular > > > > dependency. Any other ideas? > > > > > > Move the waiting into an out-of-line slow-path? > > > > > > if (atomic_read(&vma->refcnt) !=3D 2) > > > __vma_write_start_wait(mm, vma); > > > > The problem is not a function but the addition of struct rcuwait into > > Durr, in my brain that was a struct task_struct pointer, totally forgot > we had a type there. Yeah, as Willy says, move it to compiler_types.h or > somesuch. Got it. Thank you both!