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AJvYcCUTSOBdy3afUgEAyoCrKad3eJwRTLdQbLWna+JkiiaSusR8E2wtF5gW+cezu5xhxc/1BNDit+jhaw==@kvack.org X-Gm-Message-State: AOJu0YzsPQujTVg4HvabNLwo5vuLxV6heZB7KbaFBqYeS/Yn+tg2Vcmm EO9PvUKRqo/PAOhlgirwKpj9t2gC7lK6K6Pl5PJ6n0ill8PjiFoJWK7f/diiNfmNfNUym80g23x 3K8GgRLaBFlSi9d2F7AHQ930kGIY= X-Google-Smtp-Source: AGHT+IGz7ULrL/xoNu5+rVxJsNZlD+tDD1RJbGgRccyic28alkfr8h3zJBxXB5fAn56GxrJNoWw7RQtGGn0zmHw7i2o= X-Received: by 2002:a05:6a20:d805:b0:1d9:261c:5943 with SMTP id adf61e73a8af0-1d978ad5a29mr9768557637.10.1729812024062; Thu, 24 Oct 2024 16:20:24 -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: Andrii Nakryiko Date: Thu, 24 Oct 2024 16:20:11 -0700 Message-ID: Subject: Re: [PATCH v3 tip/perf/core 1/4] mm: introduce mmap_lock_speculation_{start|end} To: Suren Baghdasaryan Cc: Peter Zijlstra , 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-Stat-Signature: uu6uuw4dq6r4ac7dpbwgypnasojw3mri X-Rspamd-Queue-Id: 579C3120005 X-Rspamd-Server: rspam02 X-HE-Tag: 1729812000-40392 X-HE-Meta: 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 G9lPPueW 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, 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 2:04=E2=80=AFPM Suren Baghdasaryan wrote: > > 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 lon= g. > > > > 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. Specifical= ly > > > preemptible seqcount will be similarly affected. So we should probabl= y > > > 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/. Thanks, Suren! Hopefully it can land soon! > > > > > >