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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 615B6C433EF for ; Sun, 3 Apr 2022 23:52:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1376742AbiDCXyP (ORCPT ); Sun, 3 Apr 2022 19:54:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55152 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233854AbiDCXyL (ORCPT ); Sun, 3 Apr 2022 19:54:11 -0400 Received: from mail-pg1-x52e.google.com (mail-pg1-x52e.google.com [IPv6:2607:f8b0:4864:20::52e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 304853878E for ; Sun, 3 Apr 2022 16:52:17 -0700 (PDT) Received: by mail-pg1-x52e.google.com with SMTP id c2so6933249pga.10 for ; Sun, 03 Apr 2022 16:52:17 -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=jnxVFLHekOunLtWoWlKj8zJBbrok1zNY71HOhIA5VLo=; b=h1wuTbzfBbOsaQ8zE5QA8LCpBtZ1Hce3UXsIXzo1B/3iG/5mu/rQF1Ik3zyIbg9MiG 6K01wodbxSsbULqeK0a+idZPqasVp5/mTTU8jzeghj7zCpFv8912e+2bkwQP4xjfJajO Fbxtujqq3nMtIbwPf5p7g9/h8zlMz11LmyKuUt1BGZJWQSf2DwxX+/NchFm2ZEp80LQU gtNt+4i5Dp2mDmB/LUGUwXxPeJqObJfXT5i77TbHjvUseu5XHRRV5C8d95nQVGYeO5M3 gVBNGEjvMqOMNl9Dqxp7UDCEQtJw44sOhwNJ0DBLt9jwj+Hz3qyB4havcHY5bMin7u27 KBaw== 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=jnxVFLHekOunLtWoWlKj8zJBbrok1zNY71HOhIA5VLo=; b=78BW7huem8eTt6vJdpszcBxewMHpadhoE+b7bfM67k8xEt92yQebkBn6vOtnG7Yi+y T3xsaqq43YYQnnUyWt5haeEazHgTaeZDXHJ4MM1p6jWjNA4mjQx3ki6GoxY8LOEmpGia TAfRynJKC0JB+LzX0bWvFCkIICPBl9dnS39zMpuoYCImeLStOnd8VkYmhcRGYfRBorbj ifUs7rvisEuVJJfYdSSH3Hc1z8QpxJBm2h1LLbRO1I69kctAq5dHe2LTOgDEITf1ow+Y dt+AXXXV4UkYoMrvllHtGvJyHOR7xsgMpwORiwF0gE1gT6NcvcdwNmBempl8/wZBrkm+ osBA== X-Gm-Message-State: AOAM532EChprSqCN+vZcgL9NJb5R3IOAXkDah7aPXfgRXtoCJ7Wmujz9 973XKsydmnmoU8/1s/jx7kyVR2OA+yk= X-Google-Smtp-Source: ABdhPJx0X1oiRABWDciIM9Dn/oUkVnyHhiYKy0/X8Aw3CetecnyuaBA+wneyVoZkDN9jqQvT9ahY0A== X-Received: by 2002:a05:6a00:1581:b0:4fa:e6d4:c3e6 with SMTP id u1-20020a056a00158100b004fae6d4c3e6mr21063889pfk.84.1649029936590; Sun, 03 Apr 2022 16:52:16 -0700 (PDT) Received: from octofox.hsd1.ca.comcast.net ([2601:641:401:1d20:98f7:b9d3:817b:7621]) by smtp.gmail.com with ESMTPSA id u17-20020a056a00159100b004faef351ebcsm9789697pfk.45.2022.04.03.16.52.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 03 Apr 2022 16:52:15 -0700 (PDT) From: Max Filippov To: Thomas Gleixner Cc: "Peter Zijlstra (Intel)" , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Max Filippov Subject: [PATCH] highmem: fix checks in __kmap_local_sched_{in,out} Date: Sun, 3 Apr 2022 16:51:59 -0700 Message-Id: <20220403235159.3498065-1-jcmvbkbc@gmail.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Fixes: 5fbda3ecd14a ("sched: highmem: Store local kmaps in task struct") Signed-off-by: Max Filippov --- mm/highmem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/highmem.c b/mm/highmem.c index 762679050c9a..916b66e0776c 100644 --- a/mm/highmem.c +++ b/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))) -- 2.30.2