From patchwork Mon Apr 4 19:23:20 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 556176 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 A452FC4321E for ; Mon, 4 Apr 2022 21:17:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240513AbiDDVTf (ORCPT ); Mon, 4 Apr 2022 17:19:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59298 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1380266AbiDDTZS (ORCPT ); Mon, 4 Apr 2022 15:25:18 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 57D2E3B037; Mon, 4 Apr 2022 12:23:22 -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 CD06160E07; Mon, 4 Apr 2022 19:23:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 26F08C2BBE4; Mon, 4 Apr 2022 19:23:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1649100201; bh=FIdzzLgCt+ibG7BLkK9z9odlDVaP2an4lCC1DuV652s=; h=Date:To:From:Subject:From; b=WAeQJgXDkIFuL5eY+Sj47O2f19n9BYMgg9wFIY7nYwTYoTUAXtyEtCG9r1vYvmBVx psDGxLO4+nRMjtsGRkBYs3zaMX/pp5ecvUzFf9ebdAltkI6nLq1wmcN5yrcDBWoxKw 8NBNnuumsybsAEIwxQh4ZwuektnHrKsMzMjHb95w= Date: Mon, 04 Apr 2022 12:23:20 -0700 To: mm-commits@vger.kernel.org, tglx@linutronix.de, stable@vger.kernel.org, peterz@infradead.org, jcmvbkbc@gmail.com, akpm@linux-foundation.org From: Andrew Morton Subject: + highmem-fix-checks-in-__kmap_local_sched_inout.patch added to -mm tree Message-Id: <20220404192321.26F08C2BBE4@smtp.kernel.org> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch titled Subject: highmem: fix checks in __kmap_local_sched_{in,out} has been added to the -mm tree. Its filename is highmem-fix-checks-in-__kmap_local_sched_inout.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/highmem-fix-checks-in-__kmap_local_sched_inout.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/highmem-fix-checks-in-__kmap_local_sched_inout.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ 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)))