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AJvYcCUSfa6LBk+D330uPepEbPtnsxRirDXa26DcpzsVMhkxxexDGMKhWMd6bS92Yi1Wd4O0mqxcD8n5FA==@kvack.org X-Gm-Message-State: AOJu0Yx32X1rewxq50pEu+0WO5YzxpUwOSOFV+XfTK9b3Zqw/KWHCaMu uEvDBExRW5zpKGU/ffz0mgGvCSFQWErkt2YsAMURlbpKFEdtIAoiYZSqRAqCkyIkdbsK+/lKN+p lW/m696AiNIkcgCH0RkKRGPerzbQ= X-Google-Smtp-Source: AGHT+IEgBQBY50NgmUSwv7WeWN6RgmhxUSqpC8efKbbtYOPUDXTyDNRkjloglseKzk4fJn/E39uuA/XUO26JB9Ea3Yo= X-Received: by 2002:a05:6a21:9206:b0:1d9:1784:49f with SMTP id adf61e73a8af0-1d978bd6445mr3959442637.46.1729710733319; Wed, 23 Oct 2024 12:12:13 -0700 (PDT) MIME-Version: 1.0 References: <20241010205644.3831427-1-andrii@kernel.org> <20241010205644.3831427-3-andrii@kernel.org> <55hskn2iz5ixsl6wvupnhx7hkzcvx2u4muswvzi4wuqplmu2uo@rj72ypyeksjy> <20241023190240.GA11151@noisy.programming.kicks-ass.net> In-Reply-To: <20241023190240.GA11151@noisy.programming.kicks-ass.net> From: Andrii Nakryiko Date: Wed, 23 Oct 2024 12:12:00 -0700 Message-ID: Subject: Re: [PATCH v3 tip/perf/core 2/4] mm: switch to 64-bit mm_lock_seq/vm_lock_seq on 64-bit architectures To: Peter Zijlstra Cc: Suren Baghdasaryan , Shakeel Butt , 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, hannes@cmpxchg.org, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 5B7C3100028 X-Stat-Signature: bwsjdcrtw9sjj1wcc9w8q4uo9z6uc6tj X-Rspam-User: X-HE-Tag: 1729710701-264699 X-HE-Meta: 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 t+yIgQpT 0MCokK1J149QWegAShZ7xCZGY38Nv+zZmnHZRTKVIu6WIb3+6DZbYDZ9oV6SqAqJyLy5f9aDSv/mlB5VYmupwpPtoPtSYcppGNwljaPfyp2r4leMMUDodTN/M38PZrnP44hTL8imFIQkpOjFucMoQ1tyM88S8s0sg7bqzxUOqxZ48B0SMV7REaWdPYrULWwNj/EEzeuiAOMkCBZReYJMraCNEnRTn3x+ynapQ72u+0y0+WYhrRl+q7WvZiXqQAbZyi8eZ1hftKU6JuVFj/+hgPUG8eZKiiKc0anDe5xZnu+8/VrmIh+9a7JYYQbAAfLfsFt8IkT4kRbk6sNh0nVdH1fDEloytujsj5DIhagkPjU37vJAcqcMJUK7axMgx0leqb3ZhlUoFWXa87uOh6JVZh188f9vDqzdKwNW/NRPpzLdVaaaIMZfDU/dIZ1+5KFdFav73TysEw2Zfwyo= X-Bogosity: Ham, tests=bogofilter, spamicity=0.006522, 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 Wed, Oct 23, 2024 at 12:02=E2=80=AFPM Peter Zijlstra wrote: > > On Wed, Oct 16, 2024 at 07:01:59PM -0700, Suren Baghdasaryan wrote: > > On Sun, Oct 13, 2024 at 12:56=E2=80=AFAM Shakeel Butt wrote: > > > > > > On Thu, Oct 10, 2024 at 01:56:42PM GMT, Andrii Nakryiko wrote: > > > > To increase mm->mm_lock_seq robustness, switch it from int to long,= so > > > > that it's a 64-bit counter on 64-bit systems and we can stop worryi= ng > > > > about it wrapping around in just ~4 billion iterations. Same goes f= or > > > > VMA's matching vm_lock_seq, which is derived from mm_lock_seq. > > > > vm_lock_seq does not need to be long but for consistency I guess that > > makes sense. While at it, can you please change these seq counters to > > be unsigned? > > Yeah, that. Kees is waging war on signed types that 'overflow'. These > sequence counter thingies are designed to wrap and should very much be > unsigned. Ah, ok, I already forgot I need to update this. Will do.