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 EFAC3C636D7 for ; Fri, 17 Feb 2023 02:56:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230195AbjBQC4Z (ORCPT ); Thu, 16 Feb 2023 21:56:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60644 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229489AbjBQC4X (ORCPT ); Thu, 16 Feb 2023 21:56:23 -0500 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C6EA5382B for ; Thu, 16 Feb 2023 18:56:21 -0800 (PST) Received: from dggpemm500014.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4PHxJn4D1LzrRsv; Fri, 17 Feb 2023 10:55:53 +0800 (CST) Received: from localhost.localdomain (10.175.112.125) by dggpemm500014.china.huawei.com (7.185.36.153) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.17; Fri, 17 Feb 2023 10:56:19 +0800 From: Wupeng Ma To: , , , CC: , , , , , , Subject: [RFC PATCH 1/1] x86/mm/pat: Clear VM_PAT if copy_p4d_range failed Date: Fri, 17 Feb 2023 10:56:15 +0800 Message-ID: <20230217025615.1595558-1-mawupeng1@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.112.125] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500014.china.huawei.com (7.185.36.153) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ma Wupeng x86/mm/pat: Clear VM_PAT if copy_p4d_range failed. Syzbot reports a warning in untrack_pfn(). Digging into the root we found that this is due to memory allocation failure in pmd_alloc_one. And this failure is produced due to failslab. In copy_page_range(), memory alloaction for pmd failed. During the error handling process in copy_page_range(), mmput() is called to remove all vmas. While untrack_pfn this empty pfn, warning happens. Here's a simplified flow: dup_mm dup_mmap copy_page_range copy_p4d_range copy_pud_range copy_pmd_range pmd_alloc __pmd_alloc pmd_alloc_one page = alloc_pages(gfp, 0); if (!page) return NULL; mmput exit_mmap unmap_vmas unmap_single_vma untrack_pfn follow_phys WARN_ON_ONCE(1); Since this vma is not generate successfully, we can clear flag VM_PAT. In this case, untrack_pfn() will not be called while cleaning this vma. Function untrack_pfn_moved() has also been renamed to fit the new logic. Reported-by: syzbot+5f488e922d047d8f00cc@syzkaller.appspotmail.com Signed-off-by: Ma Wupeng --- arch/x86/mm/pat/memtype.c | 12 ++++++++---- include/linux/pgtable.h | 7 ++++--- mm/memory.c | 1 + mm/mremap.c | 2 +- 4 files changed, 14 insertions(+), 8 deletions(-) diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c index fb4b1b5e0dea..558bb71ff350 100644 --- a/arch/x86/mm/pat/memtype.c +++ b/arch/x86/mm/pat/memtype.c @@ -1070,11 +1070,15 @@ void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn, } /* - * untrack_pfn_moved is called, while mremapping a pfnmap for a new region, - * with the old vma after its pfnmap page table has been removed. The new - * vma has a new pfnmap to the same pfn & cache type with VM_PAT set. + * untrack_pfn_clear is called if the following situation fits: + * + * 1) while mremapping a pfnmap for a new region, with the old vma after + * its pfnmap page table has been removed. The new vma has a new pfnmap + * to the same pfn & cache type with VM_PAT set. + * 2) while duplicating vm area, the new vma fails to copy the pgtable from + * old vma. */ -void untrack_pfn_moved(struct vm_area_struct *vma) +void untrack_pfn_clear(struct vm_area_struct *vma) { vma->vm_flags &= ~VM_PAT; } diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 1159b25b0542..e211124f4330 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -1219,9 +1219,10 @@ static inline void untrack_pfn(struct vm_area_struct *vma, } /* - * untrack_pfn_moved is called while mremapping a pfnmap for a new region. + * untrack_pfn_clear is called while mremapping a pfnmap for a new region + * or fails to copy pgtable during duplicate vm area. */ -static inline void untrack_pfn_moved(struct vm_area_struct *vma) +static inline void untrack_pfn_clear(struct vm_area_struct *vma) { } #else @@ -1233,7 +1234,7 @@ extern void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot, extern int track_pfn_copy(struct vm_area_struct *vma); extern void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn, unsigned long size); -extern void untrack_pfn_moved(struct vm_area_struct *vma); +extern void untrack_pfn_clear(struct vm_area_struct *vma); #endif #ifdef CONFIG_MMU diff --git a/mm/memory.c b/mm/memory.c index f526b9152bef..846d4136d1de 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1278,6 +1278,7 @@ copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) continue; if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd, addr, next))) { + untrack_pfn_clear(dst_vma); ret = -ENOMEM; break; } diff --git a/mm/mremap.c b/mm/mremap.c index 930f65c315c0..6ed28eeae5a8 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -682,7 +682,7 @@ static unsigned long move_vma(struct vm_area_struct *vma, /* Tell pfnmap has moved from this vma */ if (unlikely(vma->vm_flags & VM_PFNMAP)) - untrack_pfn_moved(vma); + untrack_pfn_clear(vma); if (unlikely(!err && (flags & MREMAP_DONTUNMAP))) { /* We always clear VM_LOCKED[ONFAULT] on the old vma */ -- 2.25.1