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V" , Andrew Morton , Nick Piggin , Peter Zijlstra , Catalin Marinas , Paul Walmsley , Palmer Dabbelt , Albert Ou , Arnd Bergmann , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Nadav Amit , Andrea Arcangeli , Andy Lutomirski , Dave Hansen , Thomas Gleixner , Yu Zhao , x86@kernel.org Subject: Re: [PATCH 1/2] mm/tlb: fix fullmm semantics Message-ID: <20240103175001.GF5954@willie-the-truck> References: <20231228084642.1765-1-jszhang@kernel.org> <20231228084642.1765-2-jszhang@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20231228084642.1765-2-jszhang@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240103_095011_623642_4E8BEFAF X-CRM114-Status: GOOD ( 23.17 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Dec 28, 2023 at 04:46:41PM +0800, Jisheng Zhang wrote: > From: Nadav Amit > > fullmm in mmu_gather is supposed to indicate that the mm is torn-down > (e.g., on process exit) and can therefore allow certain optimizations. > However, tlb_finish_mmu() sets fullmm, when in fact it want to say that > the TLB should be fully flushed. > > Change tlb_finish_mmu() to set need_flush_all and check this flag in > tlb_flush_mmu_tlbonly() when deciding whether a flush is needed. > > At the same time, bring the arm64 fullmm on process exit optimization back. > > Signed-off-by: Nadav Amit > Signed-off-by: Jisheng Zhang > Cc: Andrea Arcangeli > Cc: Andrew Morton > Cc: Andy Lutomirski > Cc: Dave Hansen > Cc: Peter Zijlstra > Cc: Thomas Gleixner > Cc: Will Deacon > Cc: Yu Zhao > Cc: Nick Piggin > Cc: x86@kernel.org > --- > arch/arm64/include/asm/tlb.h | 5 ++++- > include/asm-generic/tlb.h | 2 +- > mm/mmu_gather.c | 2 +- > 3 files changed, 6 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h > index 846c563689a8..6164c5f3b78f 100644 > --- a/arch/arm64/include/asm/tlb.h > +++ b/arch/arm64/include/asm/tlb.h > @@ -62,7 +62,10 @@ static inline void tlb_flush(struct mmu_gather *tlb) > * invalidating the walk-cache, since the ASID allocator won't > * reallocate our ASID without invalidating the entire TLB. > */ > - if (tlb->fullmm) { > + if (tlb->fullmm) > + return; > + > + if (tlb->need_flush_all) { > if (!last_level) > flush_tlb_mm(tlb->mm); > return; Why isn't the 'last_level' check sufficient here? In other words, when do we perform a !last_level invalidation with 'fullmm' set outside of teardown? Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel