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Tue, 10 Feb 2026 07:32:24 -0800 (PST) Received: from DESKTOP-3LEPQG8.localdomain ([23.225.64.159]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a951a638b5sm192702675ad.11.2026.02.10.07.32.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Feb 2026 07:32:22 -0800 (PST) From: Xie Yuanbin To: dave.hansen@intel.com, peterz@infradead.org, tglx@kernel.org, riel@surriel.com, segher@kernel.crashing.org, david@kernel.org, hpa@zytor.com, arnd@arndb.de, anna-maria@linutronix.de, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, luto@kernel.org, houwenlong.hwl@antgroup.com, frederic@kernel.org, akpm@linux-foundation.org, lorenzo.stoakes@oracle.com, bhe@redhat.com, ryan.roberts@arm.com, urezki@gmail.com, nysal@linux.ibm.com, max.kellermann@ionos.com Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Xie Yuanbin Subject: Re: [PATCH v6 RESEND 1/3] x86/mm/tlb: Make enter_lazy_tlb() always inline on x86 Date: Tue, 10 Feb 2026 23:32:02 +0800 Message-ID: <20260210153202.524-1-qq570070308@gmail.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <2e8bf3e4-162d-4245-b438-8f8896a48960@intel.com> References: <2e8bf3e4-162d-4245-b438-8f8896a48960@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Mon, 9 Feb 2026 11:24:06 -0800, Dave Hansen wrote: > On 2/9/26 08:23, Xie Yuanbin wrote: >> +/* >> + * Please ignore the name of this function. It should be called >> + * switch_to_kernel_thread(). >> + * >> + * enter_lazy_tlb() is a hint from the scheduler that we are entering a >> + * kernel thread or other context without an mm. Acceptable implementations >> + * include doing nothing whatsoever, switching to init_mm, or various clever >> + * lazy tricks to try to minimize TLB flushes. >> + * >> + * The scheduler reserves the right to call enter_lazy_tlb() several times >> + * in a row. It will notify us that we're going back to a real mm by >> + * calling switch_mm_irqs_off(). >> + */ >> +#ifndef MODULE > > What's with the #ifndef? Is this to avoid use spreading to modules and > then making us export some other gunk? That seems like a generally good > thing, but it's also totally random, different from the existing > 'extern' declaration of enter_lazy_tlb(), and unique in the header. This was just to fix a compilation error: 'cpu_tlbstate' is defined in 'include/asm/tlbflush.h' inside of '#ifndef MODULE'. So if the '#ifndef MODULE' is not added here, the compilation error will be triggered: ```log arch/x86/include/asm/mmu_context.h: In function 'enter_lazy_tlb': arch/x86/include/asm/mmu_context.h:155:27: error: 'cpu_tlbstate' undeclared (first use in this function); did you mean 'cpuhp_state'? 155 | if (this_cpu_read(cpu_tlbstate.loaded_mm) == &init_mm) | ^~~~~~~~~~~~ ```