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AJvYcCWFiRn+j82pIaydg2L6LsBnYaaaFAPRVSHLTojMiu4gpXIJNGlv4hwegXtQBK/srCigMeXEFyoK+Q==@kvack.org X-Gm-Message-State: AOJu0YyOwniGgXOOEgB86/+xtuGk6WIzJuTHXVOOYWgmHeS8HhIgB04P 2W7yPqPF1Q6tsVRtdJ6HUr0SAFNdXNSASNj0Ve5ppjK2wMPfJLq18UOEZUBImfvptZZz26n+CdA XZuFdb2b+GIkaM9n+fiDycvYrIWM= X-Gm-Gg: ASbGncu1BfZvSt/XwQNJzsDLqOioCoYUvA5R8DhjRzGqiI2A7VYyMvXzrMeGKBvLxaT neIhvXxhVlerhVi7rWA90OvPjUe5l90G4E5EWB7ddtTkvWzaPsf/eXMSkGKtHb1AyhenXmhc= X-Google-Smtp-Source: AGHT+IGJ7g3FpSwfuXumgPGfVu8WTf22uug054DFKUwLfW91aWgHDJLQhy/zNtXop1WlJukQZapOIgioQXUMjhts0No= X-Received: by 2002:a05:6402:34c3:b0:5d0:81af:4a43 with SMTP id 4fb4d7f45d1cf-5dc5e6dd167mr73663a12.0.1738089504218; Tue, 28 Jan 2025 10:38:24 -0800 (PST) MIME-Version: 1.0 References: <20250128160743.3142544-1-mjguzik@gmail.com> <20250128182932.GC24845@redhat.com> In-Reply-To: <20250128182932.GC24845@redhat.com> From: Mateusz Guzik Date: Tue, 28 Jan 2025 19:38:11 +0100 X-Gm-Features: AWEUYZk_Ui_qf3h4x0PFrPEi6EByy9c8xuuesD0IPLmVNuTook6KQkzFqXAXjwI Message-ID: Subject: Re: [PATCH v2] exit: perform randomness and pid work without tasklist_lock To: Oleg Nesterov Cc: brauner@kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Eric W. Biederman" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: a6rxjh4ynqne5a9nfe9mfdogw8n3j33u X-Rspamd-Queue-Id: 1534F20004 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1738089505-847500 X-HE-Meta: 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 YWUHVr3x yPsgpgHdoz2Y7LbygtSfp2xxCOYIUxtLy8FHlLcH/DBQQSG+IxOfzw7XVDEq6adq2sRO7SOGl2mPiHvvMbTpkJgJniwRd2kvy/QFalezGa8plep2wAkLhBTiRyV1dD8HVY1pRbmlatB9dmjxcadLO0kwLEJlB8nqSJHRieH1t7k03ME4E04Y3PgUVlKuHxIChMniBf0/XCyzginwRSa0G+u+PzJcdE1GwXj1Q/NKqr9Iwwpck/t+521wYdMRwSLtHYpXG2GG0KtxM/uSGwGKwMDCYe2BEyimSmw/aPM5r+egX4POAg7FGL9Z6Wd0/6b4SxcRalN0OD/NUwAxrkug4/kuPl+NknWCDKK+Kx7BUOfnEWd6DCBOQqG9xdFifQoqzsyHwipA0Cq+0aez0ZIBZlvSVJmL9cZLc7qjO X-Bogosity: Ham, tests=bogofilter, spamicity=0.070312, 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 Tue, Jan 28, 2025 at 7:30=E2=80=AFPM Oleg Nesterov wro= te: > > (Add Eric). > > > On 01/28, Mateusz Guzik wrote: > > > > Both add_device_randomness() and attach_pid()/detach_pid() > > So afaics this patch does 2 different things, and I do think this needs > 2 separate patches. Can you split this change please? > no problem, will send a v3 provided there are no issues reported concerning the pid stuff maybe i'll add few more things pulled out to further justify the struct > As for add_device_randomness(). I must have missed something, but I still= can't > understand why we can't simply shift add_device_randomness(p->sum_exec_ru= ntime) > to release_release_task() and avoid release_task_post->randomness. > > You said: > > I wanted to keep the load where it was > > but why??? Again, I must have missed something, but to me this simply add= s the > unnecessary complications. Either way, ->sum_exec_runtime is not stable e= ven if > task-to-release !=3D current, so what is the point? > Perhaps I should preface this is not a hill I'm going to die on. :-> This is the spot which is known to work and release_task does not access the area otherwise. So for all I know someone will change it later to be freeable, zeroed for "hardening" or some other crap and the read moved to later will quietly break to always add the same value. So by default I don't want to change aspect. However, if you insist on the read to just moving, I'll be more than happy to do that in v3. --=20 Mateusz Guzik