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[209.85.167.41]) by smtp.gmail.com with ESMTPSA id a9sm9392572ljb.57.2020.08.10.11.57.48 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 10 Aug 2020 11:57:48 -0700 (PDT) Received: by mail-lf1-f41.google.com with SMTP id m15so5294891lfp.7 for ; Mon, 10 Aug 2020 11:57:48 -0700 (PDT) X-Received: by 2002:a05:6512:3b7:: with SMTP id v23mr1282665lfp.10.1597085867750; Mon, 10 Aug 2020 11:57:47 -0700 (PDT) MIME-Version: 1.0 References: <20200806231643.a2711a608dd0f18bff2caf2b@linux-foundation.org> <20200807061706.unk5_0KtC%akpm@linux-foundation.org> In-Reply-To: From: Linus Torvalds Date: Mon, 10 Aug 2020 11:57:31 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [patch 001/163] mm/memory.c: avoid access flag update TLB flush for retried page fault To: Yang Shi Cc: Andrew Morton , Catalin Marinas , Johannes Weiner , Hillf Danton , Hugh Dickins , Josef Bacik , "Kirill A . Shutemov" , Linux-MM , mm-commits@vger.kernel.org, stable , Will Deacon , Matthew Wilcox , Yu Xu , Yang Shi Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: C4E7E28A4E8 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Aug 10, 2020 at 10:48 AM Yang Shi wrote: > > It looks the retried fault still flush TLB with this change. > > Shouldn't we do something like this to skip spurious TLB flush: I have no idea what code-base you're basing your patches against, and what you're comparing my patch. Your patch does *exactly* the same thing mine did. Except it does a "goto unlock" to jump over the flush_tlb_fix_spurious_fault(), while my pseudo-patch just changed the if (vmf->flags & FAULT_FLAG_WRITE) to be a if (vmf->flags & (FAULT_FLAG_WRITE | FAULT_FLAG_TRIED)) but it has the same effect: it skips the flush_tlb_fix_spurious_fault(). So if you think your patch does something else, then your source code doesn't match mine. The *only* thing you jumped over was that same thing that I disabled. Somebody is confused. Linus