From patchwork Fri Apr 9 20:27:44 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12195039 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 62C05C43461 for ; Fri, 9 Apr 2021 20:27:47 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1152361178 for ; Fri, 9 Apr 2021 20:27:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1152361178 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 A8D846B0083; Fri, 9 Apr 2021 16:27:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A64776B0085; Fri, 9 Apr 2021 16:27:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 952216B0087; Fri, 9 Apr 2021 16:27:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0092.hostedemail.com [216.40.44.92]) by kanga.kvack.org (Postfix) with ESMTP id 7AEAD6B0083 for ; Fri, 9 Apr 2021 16:27:46 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 41FD78248047 for ; Fri, 9 Apr 2021 20:27:46 +0000 (UTC) X-FDA: 78013964532.14.D211E46 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf11.hostedemail.com (Postfix) with ESMTP id 5F0EC2000255 for ; Fri, 9 Apr 2021 20:27:39 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id C7899610A8; Fri, 9 Apr 2021 20:27:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1618000065; bh=xSdAOEalDE+MzSeUP8Q8DSnNQTJEg6WUR9CPuoOPar8=; h=Date:From:To:Subject:In-Reply-To:From; b=XSp8yRitph7lvDT4yJN8Rpy4cGM3NGSaT9a8GcnXdz3Pgg9LtOIeUoyBCO/zISG0O +gQaly/gfbkBe+CLCKS2V1qwXM8f4vRVOi6oAL770VscXXITe0IXxIVY7Ll+60khX8 3FCAuIijPuZUTZfvNkfm68/79AJawHwy1uu9FHo4= Date: Fri, 09 Apr 2021 13:27:44 -0700 From: Andrew Morton To: akpm@linux-foundation.org, andreyknvl@google.com, dvyukov@google.com, elver@google.com, glider@google.com, jannh@google.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, tomi.p.sarvela@intel.com, torvalds@linux-foundation.org Subject: [patch 15/16] kfence, x86: fix preemptible warning on KPTI-enabled systems Message-ID: <20210409202744.raBMoNOTx%akpm@linux-foundation.org> In-Reply-To: <20210409132633.6855fc8fea1b3905ea1bb4be@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 5F0EC2000255 X-Stat-Signature: emjkpxw5tqdja6e8fsnxcqhsk8wukb3h Received-SPF: none (linux-foundation.org>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618000059-992272 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: Marco Elver Subject: kfence, x86: fix preemptible warning on KPTI-enabled systems On systems with KPTI enabled, we can currently observe the following warning: BUG: using smp_processor_id() in preemptible caller is invalidate_user_asid+0x13/0x50 CPU: 6 PID: 1075 Comm: dmesg Not tainted 5.12.0-rc4-gda4a2b1a5479-kfence_1+ #1 Hardware name: Hewlett-Packard HP Pro 3500 Series/2ABF, BIOS 8.11 10/24/2012 Call Trace: dump_stack+0x7f/0xad check_preemption_disabled+0xc8/0xd0 invalidate_user_asid+0x13/0x50 flush_tlb_one_kernel+0x5/0x20 kfence_protect+0x56/0x80 ... While it normally makes sense to require preemption to be off, so that the expected CPU's TLB is flushed and not another, in our case it really is best-effort (see comments in kfence_protect_page()). Avoid the warning by disabling preemption around flush_tlb_one_kernel(). Link: https://lore.kernel.org/lkml/YGIDBAboELGgMgXy@elver.google.com/ Link: https://lkml.kernel.org/r/20210330065737.652669-1-elver@google.com Signed-off-by: Marco Elver Reported-by: Tomi Sarvela Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Andrey Konovalov Cc: Jann Horn Signed-off-by: Andrew Morton --- arch/x86/include/asm/kfence.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/arch/x86/include/asm/kfence.h~kfence-x86-fix-preemptible-warning-on-kpti-enabled-systems +++ a/arch/x86/include/asm/kfence.h @@ -56,8 +56,13 @@ static inline bool kfence_protect_page(u else set_pte(pte, __pte(pte_val(*pte) | _PAGE_PRESENT)); - /* Flush this CPU's TLB. */ + /* + * Flush this CPU's TLB, assuming whoever did the allocation/free is + * likely to continue running on this CPU. + */ + preempt_disable(); flush_tlb_one_kernel(addr); + preempt_enable(); return true; }