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(p200300cbc705df0067e85c3dde724929.dip0.t-ipconnect.de. [2003:cb:c705:df00:67e8:5c3d:de72:4929]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43d43f3328bsm14433465e9.1.2025.03.19.03.16.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 19 Mar 2025 03:16:37 -0700 (PDT) Message-ID: <50f03347-0586-4284-b02d-b16abf89e656@redhat.com> Date: Wed, 19 Mar 2025 11:16:36 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [tip: x86/mm] x86/mm/pat: Fix VM_PAT handling when fork() fails in copy_page_range() To: Borislav Petkov Cc: linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org, xingwei lee , yuxin wang , Marius Fleischer , Ingo Molnar , Andrew Morton , Linus Torvalds , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Rik van Riel , "H. Peter Anvin" , Peter Xu , x86@kernel.org, Dan Carpenter References: <20241029210331.1339581-1-david@redhat.com> <174100624258.10177.4534865061014070904.tip-bot2@tip-bot2> <20250319095357.GAZ9qUNaWSORZMXdRK@fat_crate.local> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20250319095357.GAZ9qUNaWSORZMXdRK@fat_crate.local> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 19.03.25 10:53, Borislav Petkov wrote: > On Wed, Mar 19, 2025 at 09:15:25AM +0100, David Hildenbrand wrote: >> @Ingo, can you drop this patch for now? It's supposed to be "!get_pat_info" >> here, and I want to re-verify now that a couple of months passed, whether >> it's all working as expected with that. >> >> (we could actually complain if get_pat_info() would fail at this point, let >> me think about that) >> >> I'll resend once I get to it. Thanks! > > That patch is deep into the x86/mm branch. We could > > - rebase: not good, especially one week before the merge window > > - send a revert: probably better along with an explanation why we're reverting > > - do a small fix which disables it ontop > > - fix it properly: probably best! :-) Ahh, the commit id is already supposed to be stable, got it. I'm currently testing the following as fix, that avoids the second lookup completely. From 0f42e29d5ba413affa2494f9cbbdf7b5b6b4ae2e Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Fri, 18 Oct 2024 12:44:59 +0200 Subject: [PATCH v1] x86/mm/pat: fix error handling in untrack_pfn_copy() We perform another get_pat_info() to lookup the PFN, but we accidentally Let's fix it by just avoiding another get_pat_info() completely, simplifying untrack_pfn_copy() to simply call untrack_pfn() with the pfn obtained through track_pfn_copy(). Reported-by: Dan Carpenter Closes: https://lkml.kernel.org/r/lore.kernel.org/r/1d5de3d6-999b-47ca-8d43-22703b8442bc@stanley.mountain Cc: Dave Hansen Cc: Andy Lutomirski Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: Peter Xu Cc: Andrew Morton Cc: Ma Wupeng Signed-off-by: David Hildenbrand --- arch/x86/mm/pat/memtype.c | 32 ++++---------------------------- include/linux/pgtable.h | 23 ++++++++++++++++++----- mm/memory.c | 6 +++--- 3 files changed, 25 insertions(+), 36 deletions(-) diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c index 3a9e6dd58e2f0..dc5c8e6e3001e 100644 --- a/arch/x86/mm/pat/memtype.c +++ b/arch/x86/mm/pat/memtype.c @@ -985,7 +985,7 @@ static int get_pat_info(struct vm_area_struct *vma, resource_size_t *paddr, } int track_pfn_copy(struct vm_area_struct *dst_vma, - struct vm_area_struct *src_vma) + struct vm_area_struct *src_vma, unsigned long *pfn) { const unsigned long vma_size = src_vma->vm_end - src_vma->vm_start; resource_size_t paddr; @@ -1002,36 +1002,12 @@ int track_pfn_copy(struct vm_area_struct *dst_vma, if (get_pat_info(src_vma, &paddr, &pgprot)) return -EINVAL; rc = reserve_pfn_range(paddr, vma_size, &pgprot, 1); - if (!rc) + if (!rc) { /* Reservation for the destination VMA succeeded. */ vm_flags_set(dst_vma, VM_PAT); - return rc; -} - -void untrack_pfn_copy(struct vm_area_struct *dst_vma, - struct vm_area_struct *src_vma) -{ - resource_size_t paddr; - unsigned long size; - - if (!(dst_vma->vm_flags & VM_PAT)) - return; - - /* - * As the page tables might not have been copied yet, the PAT - * information is obtained from the src VMA, just like during - * track_pfn_copy(). - */ - if (get_pat_info(src_vma, &paddr, NULL)) { - size = src_vma->vm_end - src_vma->vm_start; - free_pfn_range(paddr, size); + *pfn = PHYS_PFN(paddr); } - - /* - * Reservation was freed, any copied page tables will get cleaned - * up later, but without getting PAT involved again. - */ - vm_flags_clear(dst_vma, VM_PAT); + return rc; } /* diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index acf387d199d7b..97f8afccfec76 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -1509,10 +1509,11 @@ static inline void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot, /* * track_pfn_copy is called when a VM_PFNMAP VMA is about to get the page - * tables copied during copy_page_range(). + * tables copied during copy_page_range(). Returns the pfn to be passed to + * untrack_pfn_copy() if anything goes wrong while copying page tables. */ static inline int track_pfn_copy(struct vm_area_struct *dst_vma, - struct vm_area_struct *src_vma) + struct vm_area_struct *src_vma, unsigned long *pfn) { return 0; } @@ -1553,14 +1554,26 @@ extern int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot, extern void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot, pfn_t pfn); extern int track_pfn_copy(struct vm_area_struct *dst_vma, - struct vm_area_struct *src_vma); -extern void untrack_pfn_copy(struct vm_area_struct *dst_vma, - struct vm_area_struct *src_vma); + struct vm_area_struct *src_vma, unsigned long *pfn); extern void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn, unsigned long size, bool mm_wr_locked); extern void untrack_pfn_clear(struct vm_area_struct *vma); #endif +/* + * untrack_pfn_copy is called when a VM_PFNMAP VMA failed to copy during + * copy_page_range(), but after track_pfn_copy() was already called. + */ +static inline void untrack_pfn_copy(struct vm_area_struct *dst_vma, + unsigned long pfn) +{ + untrack_pfn(dst_vma, pfn, dst_vma->vm_end - dst_vma->vm_start, true); + /* + * Reservation was freed, any copied page tables will get cleaned + * up later, but without getting PAT involved again. + */ +} + #ifdef CONFIG_MMU #ifdef __HAVE_COLOR_ZERO_PAGE static inline int is_zero_pfn(unsigned long pfn) diff --git a/mm/memory.c b/mm/memory.c index e4b6e599c34d8..dc8efa1358e94 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1362,12 +1362,12 @@ int copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) { pgd_t *src_pgd, *dst_pgd; - unsigned long next; unsigned long addr = src_vma->vm_start; unsigned long end = src_vma->vm_end; struct mm_struct *dst_mm = dst_vma->vm_mm; struct mm_struct *src_mm = src_vma->vm_mm; struct mmu_notifier_range range; + unsigned long next, pfn; bool is_cow; int ret; @@ -1378,7 +1378,7 @@ copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) return copy_hugetlb_page_range(dst_mm, src_mm, dst_vma, src_vma); if (unlikely(src_vma->vm_flags & VM_PFNMAP)) { - ret = track_pfn_copy(dst_vma, src_vma); + ret = track_pfn_copy(dst_vma, src_vma, &pfn); if (ret) return ret; } @@ -1425,7 +1425,7 @@ copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) mmu_notifier_invalidate_range_end(&range); } if (ret && unlikely(src_vma->vm_flags & VM_PFNMAP)) - untrack_pfn_copy(dst_vma, src_vma); + untrack_pfn_copy(dst_vma, pfn); return ret; } -- 2.48.1 -- Cheers, David / dhildenb