From nobody Sun Apr 19 00:24:32 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C56D8CCA47F for ; Fri, 8 Jul 2022 08:05:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237629AbiGHIFe (ORCPT ); Fri, 8 Jul 2022 04:05:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40678 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237149AbiGHIFb (ORCPT ); Fri, 8 Jul 2022 04:05:31 -0400 Received: from mail-pj1-x102c.google.com (mail-pj1-x102c.google.com [IPv6:2607:f8b0:4864:20::102c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 30EA380488 for ; Fri, 8 Jul 2022 01:05:31 -0700 (PDT) Received: by mail-pj1-x102c.google.com with SMTP id v4-20020a17090abb8400b001ef966652a3so1180048pjr.4 for ; Fri, 08 Jul 2022 01:05:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=KpsViEXZYHaSKdo2Y5tfQa2GHPWQpzwRjvyBNJo59WU=; b=QD+aXyufjYV5Rhg7g9mfLcGxaoTj7cmPQTrt3D9uRtWwYIH8z6Valy/m/ZlLU7GeiT 1EnfnMAEEekJP2mj88bW+jDYHsM+CJ5HSgYc03i+rLDa/K26IcLX7dDBB8n8qZWjD6Pk 1/WG8KcKtyXf2eHl6M0nDWp3YEfU+dkn1DAACfrWjXSt6kPCHsuhmG4pk6jtiRZRJFLV Or/krkaK+/Hc2bddE6KxyoiuQ5W5z3Sk/MRH1seFkab8gN0j6IHeiC4CKI2ZNb5JjwIN GiMozYnu5loweh0SxxE/VnRPyHhT+dKJRkCKtm3rSmU962lysfmEkrp88Ejw531Rluop WCKw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=KpsViEXZYHaSKdo2Y5tfQa2GHPWQpzwRjvyBNJo59WU=; b=vCQ+UYIVZ/MWiE94FRr2wh03KFXPnNinDmbkrsbMenwgR+1sFP/2XZVvpuyCTLQY+7 AJVVJfxyVLDx5XNjcDQNz6xBAtyrHacyZwQXn52elH6nCD+ZmqJPNpOkvk95cjbKIEpY eTegR8yGSJVCZR4BlWJXWvO8MTv6AgTn5kTFPZc/lZIJ8kBmZR4jQcqpgTvVnI9bJ1Uo ktQl/KWTqjHWc8GZJoqzPsigZ5ZUtuHRYh4n0/xVLHyjTWXF4H6uTeSoUDEJVP9s+T3Z jzS6d0n8u6MTKMk1eGfWXKZQwks26y4sY4bOkC0ww4IOcMbUsvKGoF3e2BgCtyg23HmT WJIw== X-Gm-Message-State: AJIora/CTLX/O+SQfeTRaM32Y2C8Uzbp9oTyROFarRBQZPXDbTX7eAcc 5K0zrJfSFfabIa1Fap0vbMMwB8MAdjo= X-Google-Smtp-Source: AGRyM1uaRRfDeP9jrOYeJppPRbXd05sAchFcz1uJ3YbkZdmE4BJ78z/Mok35DRObt1hqvwYOPFO2Pw== X-Received: by 2002:a17:902:bd43:b0:16b:953d:9e0e with SMTP id b3-20020a170902bd4300b0016b953d9e0emr2269539plx.63.1657267530175; Fri, 08 Jul 2022 01:05:30 -0700 (PDT) Received: from sc2-haas01-esx0118.eng.vmware.com ([66.170.99.1]) by smtp.gmail.com with ESMTPSA id e11-20020a6558cb000000b00408b89e4282sm27207738pgu.47.2022.07.08.01.05.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Jul 2022 01:05:29 -0700 (PDT) From: Nadav Amit X-Google-Original-From: Nadav Amit To: linux-kernel@vger.kernel.org, Hugh Dickins , Thomas Gleixner Cc: Ingo Molnar , Borislav Petkov , x86@kernel.org, Linux MM , Nadav Amit , Dave Hansen , Peter Zijlstra , Andy Lutomirski Subject: [PATCH] x86/mm/tlb: ignore f->new_tlb_gen when zero Date: Thu, 7 Jul 2022 17:30:53 -0700 Message-Id: <20220708003053.158480-1-namit@vmware.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Nadav Amit Commit aa44284960d5 ("x86/mm/tlb: Avoid reading mm_tlb_gen when possible") introduced an optimization of skipping the flush if the TLB generation that is flushed (as provided in flush_tlb_info) was already flushed. However, arch_tlbbatch_flush() does not provide any generation in flush_tlb_info. As a result, try_to_unmap_one() would not perform any TLB flushes. Fix it by checking whether f->new_tlb_gen is nonzero. Zero value is anyhow is an invalid generation value. In addition, add the missing unlikely() and jump to get tracing right. Fixes: aa44284960d5 ("x86/mm/tlb: Avoid reading mm_tlb_gen when possible") Reported-by: Hugh Dickins Cc: Dave Hansen Cc: Peter Zijlstra (Intel) Cc: Andy Lutomirski Signed-off-by: Nadav Amit Tested-by: Hugh Dickins --- arch/x86/mm/tlb.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index d9314cc8b81f..d81b4084bb8a 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -771,14 +771,14 @@ static void flush_tlb_func(void *info) return; } =20 - if (f->new_tlb_gen <=3D local_tlb_gen) { + if (unlikely(f->new_tlb_gen !=3D 0 && f->new_tlb_gen <=3D local_tlb_gen))= { /* * The TLB is already up to date in respect to f->new_tlb_gen. * While the core might be still behind mm_tlb_gen, checking * mm_tlb_gen unnecessarily would have negative caching effects * so avoid it. */ - return; + goto done; } =20 /* --=20 2.25.1