From patchwork Fri Apr 8 20:08:55 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 559179 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 718E5C4167B for ; Fri, 8 Apr 2022 20:09:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239396AbiDHULD (ORCPT ); Fri, 8 Apr 2022 16:11:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49980 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238869AbiDHULC (ORCPT ); Fri, 8 Apr 2022 16:11:02 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AAC03353ABD; Fri, 8 Apr 2022 13:08:57 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 0F58961E3D; Fri, 8 Apr 2022 20:08:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 602F9C385A6; Fri, 8 Apr 2022 20:08:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1649448536; bh=5eKCVk5qd0asycbla6RyEsTQRSE7pFO3ajyfmUWIWH4=; h=Date:To:From:In-Reply-To:Subject:From; b=kSQZn0X3m8sgM/Ekjkg8XuUrnISN5jHemzWax+Jd6SmKxcnKy9jjhSO2JDALqZEoR aWrMu9H0S6rjAhEw/d8SQm1uIfHorPI1bafdITzFRp2fBDmi0sf4qGL0dL76bYTl6Y penRUT2eyFfaGTjM1SgjSS5vlztHRFd1AXvdlVuo= Date: Fri, 08 Apr 2022 13:08:55 -0700 To: tglx@linutronix.de, stable@vger.kernel.org, peterz@infradead.org, jcmvbkbc@gmail.com, akpm@linux-foundation.org, patches@lists.linux.dev, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220408130819.a89195e527ce58dfbe0700b9@linux-foundation.org> Subject: [patch 2/9] highmem: fix checks in __kmap_local_sched_{in,out} Message-Id: <20220408200856.602F9C385A6@smtp.kernel.org> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Max Filippov Subject: highmem: fix checks in __kmap_local_sched_{in,out} When CONFIG_DEBUG_KMAP_LOCAL is enabled __kmap_local_sched_{in,out} check that even slots in the tsk->kmap_ctrl.pteval are unmapped. The slots are initialized with 0 value, but the check is done with pte_none. 0 pte however does not necessarily mean that pte_none will return true. e.g. on xtensa it returns false, resulting in the following runtime warnings: WARNING: CPU: 0 PID: 101 at mm/highmem.c:627 __kmap_local_sched_out+0x51/0x108 CPU: 0 PID: 101 Comm: touch Not tainted 5.17.0-rc7-00010-gd3a1cdde80d2-dirty #13 Call Trace: dump_stack+0xc/0x40 __warn+0x8f/0x174 warn_slowpath_fmt+0x48/0xac __kmap_local_sched_out+0x51/0x108 __schedule+0x71a/0x9c4 preempt_schedule_irq+0xa0/0xe0 common_exception_return+0x5c/0x93 do_wp_page+0x30e/0x330 handle_mm_fault+0xa70/0xc3c do_page_fault+0x1d8/0x3c4 common_exception+0x7f/0x7f WARNING: CPU: 0 PID: 101 at mm/highmem.c:664 __kmap_local_sched_in+0x50/0xe0 CPU: 0 PID: 101 Comm: touch Tainted: G W 5.17.0-rc7-00010-gd3a1cdde80d2-dirty #13 Call Trace: dump_stack+0xc/0x40 __warn+0x8f/0x174 warn_slowpath_fmt+0x48/0xac __kmap_local_sched_in+0x50/0xe0 finish_task_switch$isra$0+0x1ce/0x2f8 __schedule+0x86e/0x9c4 preempt_schedule_irq+0xa0/0xe0 common_exception_return+0x5c/0x93 do_wp_page+0x30e/0x330 handle_mm_fault+0xa70/0xc3c do_page_fault+0x1d8/0x3c4 common_exception+0x7f/0x7f Fix it by replacing !pte_none(pteval) with pte_val(pteval) != 0. Link: https://lkml.kernel.org/r/20220403235159.3498065-1-jcmvbkbc@gmail.com Fixes: 5fbda3ecd14a ("sched: highmem: Store local kmaps in task struct") Signed-off-by: Max Filippov Reviewed-by: Thomas Gleixner Cc: "Peter Zijlstra (Intel)" Cc: Signed-off-by: Andrew Morton --- mm/highmem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/mm/highmem.c~highmem-fix-checks-in-__kmap_local_sched_inout +++ a/mm/highmem.c @@ -624,7 +624,7 @@ void __kmap_local_sched_out(void) /* With debug all even slots are unmapped and act as guard */ if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) { - WARN_ON_ONCE(!pte_none(pteval)); + WARN_ON_ONCE(pte_val(pteval) != 0); continue; } if (WARN_ON_ONCE(pte_none(pteval))) @@ -661,7 +661,7 @@ void __kmap_local_sched_in(void) /* With debug all even slots are unmapped and act as guard */ if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL) && !(i & 0x01)) { - WARN_ON_ONCE(!pte_none(pteval)); + WARN_ON_ONCE(pte_val(pteval) != 0); continue; } if (WARN_ON_ONCE(pte_none(pteval)))