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 X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8485CC433E0 for ; Wed, 12 Aug 2020 01:31:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 648BC2080C for ; Wed, 12 Aug 2020 01:31:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597195903; bh=Q6rApmQDZq4TeKb8rhD6Grm+mRm2ZCIupR/XKyeYeTA=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=xk20vSF1HhwEiSTk+sr3ZDlkH0/imA3o1Dr0L/XA4q2j5R2JYM/IR1kPqF2chZEjC bVFRTxLeO+xeSCHLVdVw0XPJU2I5oD6oogBafYKblSg1LPu+AxaO+8Cw/rxKMAqIj6 FKqBJ6VuMQ/WE5Kv1AkYhb5YdK8K+Od5eQfEWF6I= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726333AbgHLBbm (ORCPT ); Tue, 11 Aug 2020 21:31:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:59264 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726609AbgHLBbk (ORCPT ); Tue, 11 Aug 2020 21:31:40 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E9BB620829; Wed, 12 Aug 2020 01:31:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597195899; bh=Q6rApmQDZq4TeKb8rhD6Grm+mRm2ZCIupR/XKyeYeTA=; h=Date:From:To:Subject:In-Reply-To:From; b=tun4aQW8B6L9tSru65vVl8Ktq5k/qZ+kcStRwR6omnE37B79qG0t8rlIgudXmB65r 82fvv7UbKpMSVz4L5nn3m0PbUy1BULxThOjBZtG3x0n+UAKXS456sPV9idRl8qIyPj Zfp7r6JH9X1utTJ2p6id4L0rHgLpS7WSwnx9peLs= Date: Tue, 11 Aug 2020 18:31:38 -0700 From: Andrew Morton To: aarcange@redhat.com, akpm@linux-foundation.org, aneesh.kumar@linux.vnet.ibm.com, dave@stgolabs.net, hughd@google.com, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, mhocko@kernel.org, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, n-horiguchi@ah.jp.nec.com, prakash.sangappa@oracle.com, stable@vger.kernel.org, torvalds@linux-foundation.org, willy@infradead.org Subject: [patch 026/165] hugetlbfs: remove call to huge_pte_alloc without i_mmap_rwsem Message-ID: <20200812013138.uoXpEHoev%akpm@linux-foundation.org> In-Reply-To: <20200811182949.e12ae9a472e3b5e27e16ad6c@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: mm-commits-owner@vger.kernel.org Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Mike Kravetz Subject: hugetlbfs: remove call to huge_pte_alloc without i_mmap_rwsem Commit c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") requires callers of huge_pte_alloc to hold i_mmap_rwsem in at least read mode. This is because the explicit locking in huge_pmd_share (called by huge_pte_alloc) was removed. When restructuring the code, the call to huge_pte_alloc in the else block at the beginning of hugetlb_fault was missed. Unfortunately, that else clause is exercised when there is no page table entry. This will likely lead to a call to huge_pmd_share. If huge_pmd_share thinks pmd sharing is possible, it will traverse the mapping tree (i_mmap) without holding i_mmap_rwsem. If someone else is modifying the tree, bad things such as addressing exceptions or worse could happen. Simply remove the else clause. It should have been removed previously. The code following the else will call huge_pte_alloc with the appropriate locking. To prevent this type of issue in the future, add routines to assert that i_mmap_rwsem is held, and call these routines in huge pmd sharing routines. Link: http://lkml.kernel.org/r/e670f327-5cf9-1959-96e4-6dc7cc30d3d5@oracle.com Fixes: c0d0381ade79 ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization") Signed-off-by: Mike Kravetz Suggested-by: Matthew Wilcox Cc: Michal Hocko Cc: Hugh Dickins Cc: Naoya Horiguchi Cc: "Aneesh Kumar K.V" Cc: Andrea Arcangeli Cc: "Kirill A.Shutemov" Cc: Davidlohr Bueso Cc: Prakash Sangappa Cc: Signed-off-by: Andrew Morton --- include/linux/fs.h | 10 ++++++++++ include/linux/hugetlb.h | 8 +++++--- mm/hugetlb.c | 15 +++++++-------- mm/rmap.c | 2 +- 4 files changed, 23 insertions(+), 12 deletions(-) --- a/include/linux/fs.h~hugetlbfs-remove-call-to-huge_pte_alloc-without-i_mmap_rwsem +++ a/include/linux/fs.h @@ -518,6 +518,16 @@ static inline void i_mmap_unlock_read(st up_read(&mapping->i_mmap_rwsem); } +static inline void i_mmap_assert_locked(struct address_space *mapping) +{ + lockdep_assert_held(&mapping->i_mmap_rwsem); +} + +static inline void i_mmap_assert_write_locked(struct address_space *mapping) +{ + lockdep_assert_held_write(&mapping->i_mmap_rwsem); +} + /* * Might pages of this file be mapped into userspace? */ --- a/include/linux/hugetlb.h~hugetlbfs-remove-call-to-huge_pte_alloc-without-i_mmap_rwsem +++ a/include/linux/hugetlb.h @@ -164,7 +164,8 @@ pte_t *huge_pte_alloc(struct mm_struct * unsigned long addr, unsigned long sz); pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr, unsigned long sz); -int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep); +int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long *addr, pte_t *ptep); void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma, unsigned long *start, unsigned long *end); struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address, @@ -203,8 +204,9 @@ static inline struct address_space *huge return NULL; } -static inline int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, - pte_t *ptep) +static inline int huge_pmd_unshare(struct mm_struct *mm, + struct vm_area_struct *vma, + unsigned long *addr, pte_t *ptep) { return 0; } --- a/mm/hugetlb.c~hugetlbfs-remove-call-to-huge_pte_alloc-without-i_mmap_rwsem +++ a/mm/hugetlb.c @@ -3967,7 +3967,7 @@ void __unmap_hugepage_range(struct mmu_g continue; ptl = huge_pte_lock(h, mm, ptep); - if (huge_pmd_unshare(mm, &address, ptep)) { + if (huge_pmd_unshare(mm, vma, &address, ptep)) { spin_unlock(ptl); /* * We just unmapped a page of PMDs by clearing a PUD. @@ -4554,10 +4554,6 @@ vm_fault_t hugetlb_fault(struct mm_struc } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) return VM_FAULT_HWPOISON_LARGE | VM_FAULT_SET_HINDEX(hstate_index(h)); - } else { - ptep = huge_pte_alloc(mm, haddr, huge_page_size(h)); - if (!ptep) - return VM_FAULT_OOM; } /* @@ -5034,7 +5030,7 @@ unsigned long hugetlb_change_protection( if (!ptep) continue; ptl = huge_pte_lock(h, mm, ptep); - if (huge_pmd_unshare(mm, &address, ptep)) { + if (huge_pmd_unshare(mm, vma, &address, ptep)) { pages++; spin_unlock(ptl); shared_pmd = true; @@ -5415,12 +5411,14 @@ out: * returns: 1 successfully unmapped a shared pte page * 0 the underlying pte page is not shared, or it is the last user */ -int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep) +int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long *addr, pte_t *ptep) { pgd_t *pgd = pgd_offset(mm, *addr); p4d_t *p4d = p4d_offset(pgd, *addr); pud_t *pud = pud_offset(p4d, *addr); + i_mmap_assert_write_locked(vma->vm_file->f_mapping); BUG_ON(page_count(virt_to_page(ptep)) == 0); if (page_count(virt_to_page(ptep)) == 1) return 0; @@ -5438,7 +5436,8 @@ pte_t *huge_pmd_share(struct mm_struct * return NULL; } -int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep) +int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma, + unsigned long *addr, pte_t *ptep) { return 0; } --- a/mm/rmap.c~hugetlbfs-remove-call-to-huge_pte_alloc-without-i_mmap_rwsem +++ a/mm/rmap.c @@ -1469,7 +1469,7 @@ static bool try_to_unmap_one(struct page * do this outside rmap routines. */ VM_BUG_ON(!(flags & TTU_RMAP_LOCKED)); - if (huge_pmd_unshare(mm, &address, pvmw.pte)) { + if (huge_pmd_unshare(mm, vma, &address, pvmw.pte)) { /* * huge_pmd_unshare unmapped an entire PMD * page. There is no way of knowing exactly _