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AJvYcCWyfLIyj2LWifsG6cIsIeYGY4ZT9ZzZPWzWkIyrlxTDQpeDJv+lYWs8kNdxS+noF/HQ0OvCGqEUjQ==@kvack.org X-Gm-Message-State: AOJu0YzQM0pfwzPS37oSjq08R7pFHgPDsHkQVyN7wKheNh3pmuBnSJLr N60iz9HaWI9FOsgAM4BG5IWZZvEQw4A1gbpVDrf0fNo/6h3qQU/WRptTX6VlppMxLKOB/tk0HPS k8ib4MceikwGwUMIXG5+aGQagQX2Ebg2SXJXa X-Google-Smtp-Source: AGHT+IGisIN/UZv7/esRlf3uon9fn8YMbFTRhXss794QzDx8oCXm0J9V3yroMLoSfTdav1KAufZuEW84U22WNwJ62yY= X-Received: by 2002:a05:622a:4b0d:b0:460:4841:8eb5 with SMTP id d75a77b69052e-461306d63f2mr89291cf.19.1729803865443; Thu, 24 Oct 2024 14:04:25 -0700 (PDT) MIME-Version: 1.0 References: <20241010205644.3831427-1-andrii@kernel.org> <20241010205644.3831427-2-andrii@kernel.org> <20241023201031.GF11151@noisy.programming.kicks-ass.net> <20241024095659.GD9767@noisy.programming.kicks-ass.net> In-Reply-To: From: Suren Baghdasaryan Date: Thu, 24 Oct 2024 14:04:12 -0700 Message-ID: Subject: Re: [PATCH v3 tip/perf/core 1/4] mm: introduce mmap_lock_speculation_{start|end} To: Peter Zijlstra Cc: Andrii Nakryiko , linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org, oleg@redhat.com, rostedt@goodmis.org, mhiramat@kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, jolsa@kernel.org, paulmck@kernel.org, willy@infradead.org, akpm@linux-foundation.org, mjguzik@gmail.com, brauner@kernel.org, jannh@google.com, mhocko@kernel.org, vbabka@suse.cz, shakeel.butt@linux.dev, hannes@cmpxchg.org, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: 88E2F40018 X-Rspamd-Server: rspam01 X-Stat-Signature: rtz3okmxekiy4odxwkhu89nmqunkh3wx X-HE-Tag: 1729803840-345302 X-HE-Meta: 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 +aRR9FgV m1NYdbA7RVIv+4iByfDpnjKmTmlmO40066bc8QOL72sTF7eWv/qbiok0nDzfy5scQvHzFZH7vcdaswrSx/Kr92vTVSv5wOFgzh6UOuvE/+glwqUQIu/Zsb1ByowXGoGSfczaCG0lfI6TYy+iMQpEry14b6shHmgk7l7w1L4Hy6cIOYeUMqvFqPB218xnX3MYl5zLWjpcrzA44kJDbdNO91ibgsjkF2QPhc4dUPy24CuA2BCi0pt+qK0ClkH8b7QLDmliSht4UN6KZ+K0tubdfXLyBRSkIshHjSX/U1vFAZRkXjN0V2MnJ0e/uCsZn7GX/3cqnVHGIOn0xsixdgg5otyNNt6lukX59Tmw7 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000019, 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 Thu, Oct 24, 2024 at 9:28=E2=80=AFAM Suren Baghdasaryan wrote: > > On Thu, Oct 24, 2024 at 2:57=E2=80=AFAM Peter Zijlstra wrote: > > > > On Wed, Oct 23, 2024 at 03:17:01PM -0700, Suren Baghdasaryan wrote: > > > > > > Or better yet, just use seqcount... > > > > > > Yeah, with these changes it does look a lot like seqcount now... > > > I can take another stab at rewriting this using seqcount_t but one > > > issue that Jann was concerned about is the counter being int vs long. > > > seqcount_t uses unsigned, so I'm not sure how to address that if I > > > were to use seqcount_t. Any suggestions how to address that before I > > > move forward with a rewrite? > > > > So if that issue is real, it is not specific to this case. Specifically > > preemptible seqcount will be similarly affected. So we should probably > > address that in the seqcount implementation. > > Sounds good. Let me try rewriting this patch using seqcount_t and I'll > work with Jann on a separate patch to change seqcount_t. > Thanks for the feedback! I posted the patchset to convert mm_lock_seq into seqcount_t and to add speculative functions at https://lore.kernel.org/all/20241024205231.1944747-1-surenb@google.com/. > > >