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Message-Id: <204B6410-2EFA-462B-9DF7-64CC5F1D3AD2@broadcom.com> Date: Sat, 30 Dec 2023 11:54:02 +0200 From: Nadav Amit <nadav.amit@...adcom.com> To: Jisheng Zhang <jszhang@...nel.org> Cc: Will Deacon <will@...nel.org>, "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>, Andrew Morton <akpm@...ux-foundation.org>, Nick Piggin <npiggin@...il.com>, Peter Zijlstra <peterz@...radead.org>, Catalin Marinas <catalin.marinas@....com>, Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, Arnd Bergmann <arnd@...db.de>, linux-arch@...r.kernel.org, linux-mm <linux-mm@...ck.org>, linux-arm-kernel@...ts.infradead.org, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, linux-riscv@...ts.infradead.org, Nadav Amit <namit@...are.com>, Andrea Arcangeli <aarcange@...hat.com>, Andy Lutomirski <luto@...nel.org>, Dave Hansen <dave.hansen@...ux.intel.com>, Thomas Gleixner <tglx@...utronix.de>, Yu Zhao <yuzhao@...gle.com>, the arch/x86 maintainers <x86@...nel.org> Subject: Re: [PATCH 1/2] mm/tlb: fix fullmm semantics > On Dec 28, 2023, at 10:46 AM, Jisheng Zhang <jszhang@...nel.org> wrote: > > From: Nadav Amit <namit@...are.com> > > 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 <namit@...are.com> > Signed-off-by: Jisheng Zhang <jszhang@...nel.org> > Cc: Andrea Arcangeli <aarcange@...hat.com> > Cc: Andrew Morton <akpm@...ux-foundation.org> > Cc: Andy Lutomirski <luto@...nel.org> > Cc: Dave Hansen <dave.hansen@...ux.intel.com> > Cc: Peter Zijlstra <peterz@...radead.org> > Cc: Thomas Gleixner <tglx@...utronix.de> > Cc: Will Deacon <will@...nel.org> > Cc: Yu Zhao <yuzhao@...gle.com> > Cc: Nick Piggin <npiggin@...il.com> > Cc: x86@...nel.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; > Thanks for pulling my patch out of the abyss, but the chunk above did not come from my old patch. My knowledge of arm64 is a bit limited, but the code does not seem to match the comment, so if it is correct (which I strongly doubt), the comment should be updated. [1] https://lore.kernel.org/all/20210131001132.3368247-2-namit@vmware.com/ -- This electronic communication and the information and any files transmitted with it, or attached to it, are confidential and are intended solely for the use of the individual or entity to whom it is addressed and may contain information that is confidential, legally privileged, protected by privacy laws, or otherwise restricted from disclosure to anyone else. If you are not the intended recipient or the person responsible for delivering the e-mail to the intended recipient, you are hereby notified that any use, copying, distributing, dissemination, forwarding, printing, or copying of this e-mail is strictly prohibited. If you received this e-mail in error, please return the e-mail to the sender, delete it from your computer, and destroy any printed copy of it.
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