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[24.6.216.183]) by smtp.gmail.com with ESMTPSA id dw13-20020a17090b094d00b00226f49eca92sm1840043pjb.28.2023.01.18.14.22.18 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 18 Jan 2023 14:22:18 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3731.300.101.1.3\)) Subject: Re: [PATCH v6 3/5] lazy tlb: shoot lazies, non-refcounting lazy tlb mm reference handling scheme From: Nadav Amit In-Reply-To: <20230118080011.2258375-4-npiggin@gmail.com> Date: Wed, 18 Jan 2023 14:22:07 -0800 Content-Transfer-Encoding: quoted-printable Message-Id: <5F3590B8-3F25-4EFB-BE3A-D32AAAC0B2F4@gmail.com> References: <20230118080011.2258375-1-npiggin@gmail.com> <20230118080011.2258375-4-npiggin@gmail.com> To: Nicholas Piggin X-Mailer: Apple Mail (2.3731.300.101.1.3) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch , linuxppc-dev@lists.ozlabs.org, linux-mm , Andy Lutomirski , Andrew Morton , Linus Torvalds Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" > On Jan 18, 2023, at 12:00 AM, Nicholas Piggin = wrote: >=20 > +static void do_shoot_lazy_tlb(void *arg) > +{ > + struct mm_struct *mm =3D arg; > + > + if (current->active_mm =3D=3D mm) { > + WARN_ON_ONCE(current->mm); > + current->active_mm =3D &init_mm; > + switch_mm(mm, &init_mm, current); > + } > +} I might be out of touch - doesn=E2=80=99t a flush already take place = when we free the page-tables, at least on common cases on x86? IIUC exit_mmap() would free page-tables, and whenever page-tables are freed, on x86, we do shootdown regardless to whether the target CPU TLB = state marks is_lazy. Then, flush_tlb_func() should call switch_mm_irqs_off() = and everything should be fine, no? [ I understand you care about powerpc, just wondering on the effect on = x86 ]