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 X-Spam-Level: X-Spam-Status: No, score=-1.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,URIBL_DBL_ABUSE_MALW autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2FCC4C35247 for ; Tue, 4 Feb 2020 01:36:56 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E76262084E for ; Tue, 4 Feb 2020 01:36:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="HgIRvqL5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E76262084E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 981556B02B7; Mon, 3 Feb 2020 20:36:55 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9585D6B02B9; Mon, 3 Feb 2020 20:36:55 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 86F1D6B02BA; Mon, 3 Feb 2020 20:36:55 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0195.hostedemail.com [216.40.44.195]) by kanga.kvack.org (Postfix) with ESMTP id 6C8876B02B7 for ; Mon, 3 Feb 2020 20:36:55 -0500 (EST) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 1D7FF2493 for ; Tue, 4 Feb 2020 01:36:55 +0000 (UTC) X-FDA: 76450730790.14.unit95_1f4198a69b52f X-HE-Tag: unit95_1f4198a69b52f X-Filterd-Recvd-Size: 3116 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf46.hostedemail.com (Postfix) with ESMTP for ; Tue, 4 Feb 2020 01:36:54 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D35A220732; Tue, 4 Feb 2020 01:36:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580780214; bh=Ip8uGc+lfdbdCdsFavdSlqR9kr9q86P1Z5bJqdTtAUc=; h=Date:From:To:Subject:In-Reply-To:From; b=HgIRvqL555A9aWT/cK4Teb1liQH40rJVRZ5x7ltz2jEp+9c4bmHfm6/EGjB2NDGH9 68/egjVflH8LZ6OPeVzs/kxbZ+5rpYlxrqmI1YQjkzm/UjorEtpUdbFOhqOowlII3d 1p/eVvU0z6YRzXbQzoFcRRyPnEF9pnSXRK81Ri+8= Date: Mon, 03 Feb 2020 17:36:53 -0800 From: Andrew Morton To: akpm@linux-foundation.org, aneesh.kumar@linux.ibm.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, mpe@ellerman.id.au, peterz@infradead.org, torvalds@linux-foundation.org Subject: [patch 50/67] asm-generic/tlb: avoid potential double flush Message-ID: <20200204013653.4NMd_OKtw%akpm@linux-foundation.org> In-Reply-To: <20200203173311.6269a8be06a05e5a4aa08a93@linux-foundation.org> User-Agent: s-nail v14.8.16 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: From: Peter Zijlstra Subject: asm-generic/tlb: avoid potential double flush Aneesh reported that: tlb_flush_mmu() tlb_flush_mmu_tlbonly() tlb_flush() <-- #1 tlb_flush_mmu_free() tlb_table_flush() tlb_table_invalidate() tlb_flush_mmu_tlbonly() tlb_flush() <-- #2 does two TLBIs when tlb->fullmm, because __tlb_reset_range() will not clear tlb->end in that case. Observe that any caller to __tlb_adjust_range() also sets at least one of the tlb->freed_tables || tlb->cleared_p* bits, and those are unconditionally cleared by __tlb_reset_range(). Change the condition for actually issuing TLBI to having one of those bits set, as opposed to having tlb->end != 0. Link: http://lkml.kernel.org/r/20200116064531.483522-4-aneesh.kumar@linux.ibm.com Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Aneesh Kumar K.V Reported-by: "Aneesh Kumar K.V" Cc: Michael Ellerman Signed-off-by: Andrew Morton --- include/asm-generic/tlb.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/include/asm-generic/tlb.h~asm-generic-tlb-avoid-potential-double-flush +++ a/include/asm-generic/tlb.h @@ -402,7 +402,12 @@ tlb_update_vma_flags(struct mmu_gather * static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb) { - if (!tlb->end) + /* + * Anything calling __tlb_adjust_range() also sets at least one of + * these bits. + */ + if (!(tlb->freed_tables || tlb->cleared_ptes || tlb->cleared_pmds || + tlb->cleared_puds || tlb->cleared_p4ds)) return; tlb_flush(tlb); _