Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752121AbdF3NSm (ORCPT ); Fri, 30 Jun 2017 09:18:42 -0400 Received: from terminus.zytor.com ([65.50.211.136]:59355 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751560AbdF3NSj (ORCPT ); Fri, 30 Jun 2017 09:18:39 -0400 Date: Fri, 30 Jun 2017 06:11:46 -0700 From: tip-bot for Andy Lutomirski Message-ID: Cc: dave.hansen@intel.com, bp@alien8.de, arjan@linux.intel.com, linux-kernel@vger.kernel.org, nadav.amit@gmail.com, hpa@zytor.com, luto@kernel.org, tglx@linutronix.de, mingo@kernel.org, akpm@linux-foundation.org, riel@redhat.com, torvalds@linux-foundation.org, mgorman@suse.de, peterz@infradead.org Reply-To: peterz@infradead.org, mingo@kernel.org, tglx@linutronix.de, torvalds@linux-foundation.org, mgorman@suse.de, akpm@linux-foundation.org, riel@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, nadav.amit@gmail.com, luto@kernel.org, bp@alien8.de, arjan@linux.intel.com, dave.hansen@intel.com In-Reply-To: <55e44997e56086528140c5180f8337dc53fb7ffc.1498751203.git.luto@kernel.org> References: <55e44997e56086528140c5180f8337dc53fb7ffc.1498751203.git.luto@kernel.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/mm] x86/mm: Delete a big outdated comment about TLB flushing Git-Commit-ID: 8781fb7e9749da424e01daacd14834b674658c63 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3104 Lines: 77 Commit-ID: 8781fb7e9749da424e01daacd14834b674658c63 Gitweb: http://git.kernel.org/tip/8781fb7e9749da424e01daacd14834b674658c63 Author: Andy Lutomirski AuthorDate: Thu, 29 Jun 2017 08:53:14 -0700 Committer: Ingo Molnar CommitDate: Fri, 30 Jun 2017 10:12:35 +0200 x86/mm: Delete a big outdated comment about TLB flushing The comment describes the old explicit IPI-based flush logic, which is long gone. Signed-off-by: Andy Lutomirski Cc: Andrew Morton Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dave Hansen Cc: Linus Torvalds Cc: Mel Gorman Cc: Nadav Amit Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/55e44997e56086528140c5180f8337dc53fb7ffc.1498751203.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/mm/tlb.c | 36 ------------------------------------ 1 file changed, 36 deletions(-) diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 1cc4783..014d07a 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -153,42 +153,6 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, switch_ldt(real_prev, next); } -/* - * The flush IPI assumes that a thread switch happens in this order: - * [cpu0: the cpu that switches] - * 1) switch_mm() either 1a) or 1b) - * 1a) thread switch to a different mm - * 1a1) set cpu_tlbstate to TLBSTATE_OK - * Now the tlb flush NMI handler flush_tlb_func won't call leave_mm - * if cpu0 was in lazy tlb mode. - * 1a2) update cpu active_mm - * Now cpu0 accepts tlb flushes for the new mm. - * 1a3) cpu_set(cpu, new_mm->cpu_vm_mask); - * Now the other cpus will send tlb flush ipis. - * 1a4) change cr3. - * 1a5) cpu_clear(cpu, old_mm->cpu_vm_mask); - * Stop ipi delivery for the old mm. This is not synchronized with - * the other cpus, but flush_tlb_func ignore flush ipis for the wrong - * mm, and in the worst case we perform a superfluous tlb flush. - * 1b) thread switch without mm change - * cpu active_mm is correct, cpu0 already handles flush ipis. - * 1b1) set cpu_tlbstate to TLBSTATE_OK - * 1b2) test_and_set the cpu bit in cpu_vm_mask. - * Atomically set the bit [other cpus will start sending flush ipis], - * and test the bit. - * 1b3) if the bit was 0: leave_mm was called, flush the tlb. - * 2) switch %%esp, ie current - * - * The interrupt must handle 2 special cases: - * - cr3 is changed before %%esp, ie. it cannot use current->{active_,}mm. - * - the cpu performs speculative tlb reads, i.e. even if the cpu only - * runs in kernel space, the cpu could load tlb entries for user space - * pages. - * - * The good news is that cpu_tlbstate is local to each cpu, no - * write/read ordering problems. - */ - static void flush_tlb_func_common(const struct flush_tlb_info *f, bool local, enum tlb_flush_reason reason) {