From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C5F48C77B75 for ; Tue, 16 May 2023 08:07:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=35JeHUsqRscjJBPF6W8dbM6pmVAf99M1k5e92gva7Do=; b=ih2j8aXDEEKAor 7Zb+SKzO5d5fdhZfQzOEERp9h/u6vGTLU/wG9rwReln4VBuOX/NnY0nJhH5EQ5jdPYCoFm/27UWcM NHun7oGLqeDzRx8YDGRKKvg4bayNyeQQKwFUcdmgIjYCLCPbPaqPpASkWaqjohZQQDpqGmMRbq6Zg 2TBu6HKnGvmfb4g5B8OEfm2vWB7u+NAh7OnKGpP/RtsW01/zKJciolvNaosJiyamHgChJdesjdaUn Ai3QIqNuYJP+T508REOx213hZ3MO2sHbJnt9+HCTCcQv4XW86Li+rr1mlkmOU7ipr+O+0RZ5P/A4a uhlRoG3lMYxjiYWm2zFQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1pypiU-004mOS-1f; Tue, 16 May 2023 08:07:30 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1pypiR-004mNB-2W for linux-arm-kernel@lists.infradead.org; Tue, 16 May 2023 08:07:29 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1684224447; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=jFjQWsSQz5NGS4jPuEzVTxLLUxVhxDPgaPzjZr1xlFo=; b=RVLPBQsN9lmeGED0yNgLHyOxfT0bFkAjKi+xkNZs+zBk/2FI3QY+WZDRj0YPevF7WEb81n jfMRb1HA+lftpk90YsAtrFD/Ybno/FcTgS2hxn/Reo0xtHI7zBAOcQo3hmSwrvf97R0cKb S52Q+59e5p9GS8bP0SdAG75TDVarqzU= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-412-N_FfV3yGM9a_z09cgAqLSQ-1; Tue, 16 May 2023 04:07:22 -0400 X-MC-Unique: N_FfV3yGM9a_z09cgAqLSQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1C83D878522; Tue, 16 May 2023 08:07:22 +0000 (UTC) Received: from localhost (ovpn-13-34.pek2.redhat.com [10.72.13.34]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EA61E40C6EC4; Tue, 16 May 2023 08:07:20 +0000 (UTC) Date: Tue, 16 May 2023 16:07:17 +0800 From: Baoquan He To: Thomas Gleixner Cc: Uladzislau Rezki , Andrew Morton , linux-mm@kvack.org, Christoph Hellwig , Lorenzo Stoakes , Peter Zijlstra , John Ogness , linux-arm-kernel@lists.infradead.org, Russell King , Mark Rutland , Marc Zyngier Subject: Re: Excessive TLB flush ranges Message-ID: References: <87a5y5a6kj.ffs@tglx> <87o7mk93tc.ffs@tglx> MIME-Version: 1.0 In-Reply-To: <87o7mk93tc.ffs@tglx> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230516_010727_888091_437B216E X-CRM114-Status: GOOD ( 21.18 ) 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 05/16/23 at 08:40am, Thomas Gleixner wrote: > On Tue, May 16 2023 at 10:26, Baoquan He wrote: > > On 05/15/23 at 08:17pm, Uladzislau Rezki wrote: > >> For systems which lack a full TLB flush and to flush a long range is > >> a problem(it takes time), probably we can flush VA one by one. Because > >> currently we calculate a flush range [min:max] and that range includes > >> the space that might not be mapped at all. Like below: > > > > It's fine if we only calculate a flush range of [min:max] with VA. In > > vm_reset_perms(), it calculates the flush range with the impacted direct > > mapping range, then merge it with VA's range. That looks really strange > > and surprising. If the vm->pages[] are got from a lower part of physical > > memory, the final merged flush will span tremendous range. Wondering why > > we need merge the direct map range with VA range, then do flush. Not > > sure if I misunderstand it. > > So what happens on this BPF teardown is: > > The vfree(8k) ends up flushing 3 entries. The actual vmalloc part (2) and > one extra which is in the direct map. I haven't verified that yet, but I > assume it's the alias of one of the vmalloc'ed pages. It looks like the reason. As Uladzislau pointed out, ARCH-es may have full TLB flush, so won't get trouble from the merged flush in the calculated [min:max] way, e.g arm64 and x86's flush_tlb_kernel_range(). However, arm32 seems lacking the ability of full TLB flash. If agreed, I can make a draft patch to do the flush for direct map and VA seperately, see if it works. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel