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))) From patchwork Fri Apr 8 20:09:04 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 559178 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 62FA3C43219 for ; Fri, 8 Apr 2022 20:09:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239395AbiDHULQ (ORCPT ); Fri, 8 Apr 2022 16:11:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50802 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239412AbiDHULP (ORCPT ); Fri, 8 Apr 2022 16:11:15 -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 A8756353ABD; Fri, 8 Apr 2022 13:09:06 -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 40D4261E3D; Fri, 8 Apr 2022 20:09:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 943B7C385A5; Fri, 8 Apr 2022 20:09:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1649448545; bh=Uwe61k3TCdIIAb9jWMhOFX99NiRwkoxxsB+Q7xD3Mck=; h=Date:To:From:In-Reply-To:Subject:From; b=vP/PnsHIBa1QkY85u2AzCWADg8BR56BgOHgbNPxvhlodwAHV2uFg+4GZaQnYjzxR7 yTGwqWwXKwNBQeH/KgPabxhmHs3C/yGHkHOxAjQusbesROJyu/SMVuFs3OGvcXXsTI WxKEvc8QjUp4poAk0vPDkxfNm2Euhwq6YXdQ791g= Date: Fri, 08 Apr 2022 13:09:04 -0700 To: stable@vger.kernel.org, seanjc@google.com, pbonzini@redhat.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 5/9] mmmremap.c: avoid pointless invalidate_range_start/end on mremap(old_size=0) Message-Id: <20220408200905.943B7C385A5@smtp.kernel.org> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Paolo Bonzini Subject: mmmremap.c: avoid pointless invalidate_range_start/end on mremap(old_size=0) If an mremap() syscall with old_size=0 ends up in move_page_tables(), it will call invalidate_range_start()/invalidate_range_end() unnecessarily, i.e. with an empty range. This causes a WARN in KVM's mmu_notifier. In the past, empty ranges have been diagnosed to be off-by-one bugs, hence the WARNing. Given the low (so far) number of unique reports, the benefits of detecting more buggy callers seem to outweigh the cost of having to fix cases such as this one, where userspace is doing something silly. In this particular case, an early return from move_page_tables() is enough to fix the issue. Link: https://lkml.kernel.org/r/20220329173155.172439-1-pbonzini@redhat.com Reported-by: syzbot+6bde52d89cfdf9f61425@syzkaller.appspotmail.com Signed-off-by: Paolo Bonzini Cc: Sean Christopherson Cc: Signed-off-by: Andrew Morton --- mm/mremap.c | 3 +++ 1 file changed, 3 insertions(+) --- a/mm/mremap.c~mm-avoid-pointless-invalidate_range_start-end-on-mremapold_size=0 +++ a/mm/mremap.c @@ -486,6 +486,9 @@ unsigned long move_page_tables(struct vm pmd_t *old_pmd, *new_pmd; pud_t *old_pud, *new_pud; + if (!len) + return 0; + old_end = old_addr + len; flush_cache_range(vma, old_addr, old_end);