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AJvYcCVe41hHb173KvpA3FWHiuc723svlvcnLWw3hLfGztOUUfgnZzcenaQ9era4winNM8ONeP4bfJao9w==@kvack.org X-Gm-Message-State: AOJu0YwNO39r/2NYKzgvmZ5ARgpSKOSWr0tC4tAGTnGzBluNPA5sgC7J sSLqG6J7+tWI+RWmkogIG2IxgCbhuDNv9poXTpln+lWghOUXjfihNWqjIBb8WGrtkWdFMzh+7+c XRSYteahUGWlGEg1qdSG1Mr/h4gDiC+ch6n4z X-Gm-Gg: ASbGnct0sF3nPvPLuvmxdmWev8CWUtPCj7qT7NlBRYLvwPJF7ej8Kycz1Xe/L3nUisB v3z6NU4xhPGKlDl5xYbw8MX0f5elXY5z/87UmPQ== X-Google-Smtp-Source: AGHT+IECtw4GIes14vwWEzxFvxaCuKJ/1TZUV17FkJlSyJ8bJOD4eX1mf6k4P4SIvfNKoqIwfABSkPrJxR4wiemjLNQ= X-Received: by 2002:a05:622a:1a27:b0:463:6f7b:250d with SMTP id d75a77b69052e-468f979beb6mr545991cf.24.1734382414158; Mon, 16 Dec 2024 12:53:34 -0800 (PST) MIME-Version: 1.0 References: <20241216192419.2970941-1-surenb@google.com> <20241216192419.2970941-11-surenb@google.com> <20241216204223.GA9803@noisy.programming.kicks-ass.net> In-Reply-To: <20241216204223.GA9803@noisy.programming.kicks-ass.net> From: Suren Baghdasaryan Date: Mon, 16 Dec 2024 12:53:23 -0800 Message-ID: Subject: Re: [PATCH v6 10/16] mm: replace vm_lock and detached flag with a reference count To: Peter Zijlstra Cc: akpm@linux-foundation.org, willy@infradead.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, lokeshgidra@google.com, minchan@google.com, jannh@google.com, shakeel.butt@linux.dev, souravpanda@google.com, pasha.tatashin@soleen.com, klarasmodin@gmail.com, corbet@lwn.net, linux-doc@vger.kernel.org, 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-Server: rspam02 X-Rspamd-Queue-Id: 8EC7E100014 X-Stat-Signature: wwjougbjjm1i95cqto6cbxndyssx4fsk X-Rspam-User: X-HE-Tag: 1734382382-515608 X-HE-Meta: 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 hj+PLkiH XpzlGTrTOaAb05CVHkZdrVwpOcd22BGag7ENHwQs3KJeLV7wWL3zDKUK7jpQPwXf7xvgHnSrEDFgZPiCqO6q2AVIuW/xYZeGHiIVLvCuuAwjkRp+NIF6GHsHw0FYgJv4EjSRJiGF6YuUNqDa8lNYPVLAHAd5eNBs5UJ1QD6zlQJt2DyKdzIeAeLWpD5Miz233dMvUaB+whO6F9OnZ3saXiQeaXp/ZPyTpnxnRyEe6y98l8dmjVarwqg36jgwlJ1UCls//H5gfThIoiRLQLyBOKWPaWzCKbb4pFqqk4TXmPFi9GvU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.301377, 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 Mon, Dec 16, 2024 at 12:42=E2=80=AFPM Peter Zijlstra wrote: > > On Mon, Dec 16, 2024 at 11:24:13AM -0800, Suren Baghdasaryan wrote: > > @@ -734,10 +761,12 @@ static inline bool vma_start_read(struct vm_area_= struct *vma) > > * after it has been unlocked. > > * This pairs with RELEASE semantics in vma_end_write_all(). > > */ > > + if (oldcnt & VMA_STATE_LOCKED || > > + unlikely(vma->vm_lock_seq =3D=3D raw_read_seqcount(&vma->vm_m= m->mm_lock_seq))) { > > You likely want that unlikely to cover both conditions :-) True. VMA_STATE_LOCKED is set only while the writer is updating the vm_lock_seq and that's a narrow window. I'll make that change in the next revision. Thanks! > > > + vma_refcount_put(vma); > > return false; > > } > > + > > return true; > > }