diff options
author | Andrey Zhizhikin <andrey.zhizhikin@leica-geosystems.com> | 2021-06-30 14:51:20 +0000 |
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committer | Andrey Zhizhikin <andrey.zhizhikin@leica-geosystems.com> | 2021-06-30 14:51:20 +0000 |
commit | 3aef3ef268648cbd4e39ddfe5c3dd8d2f22a88d2 (patch) | |
tree | cbf9c4f25ba723d2adcf6fa8b72e11bc6ad0ab5d /virt | |
parent | 02375daa33ca0e4766b0e69e0736fa1310683cd1 (diff) | |
parent | 82ffbc138a1fc9076f55e626bd8352fc9a2ca9e9 (diff) |
Merge tag 'v5.4.129' into 5.4-2.3.x-imx
Linux 5.4.129
Signed-off-by: Andrey Zhizhikin <andrey.zhizhikin@leica-geosystems.com>
Diffstat (limited to 'virt')
-rw-r--r-- | virt/kvm/kvm_main.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index f83fa0aeeb45..b2287e7d3ba4 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1593,6 +1593,13 @@ static bool vma_is_valid(struct vm_area_struct *vma, bool write_fault) return true; } +static int kvm_try_get_pfn(kvm_pfn_t pfn) +{ + if (kvm_is_reserved_pfn(pfn)) + return 1; + return get_page_unless_zero(pfn_to_page(pfn)); +} + static int hva_to_pfn_remapped(struct vm_area_struct *vma, unsigned long addr, bool *async, bool write_fault, bool *writable, @@ -1642,13 +1649,21 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma, * Whoever called remap_pfn_range is also going to call e.g. * unmap_mapping_range before the underlying pages are freed, * causing a call to our MMU notifier. + * + * Certain IO or PFNMAP mappings can be backed with valid + * struct pages, but be allocated without refcounting e.g., + * tail pages of non-compound higher order allocations, which + * would then underflow the refcount when the caller does the + * required put_page. Don't allow those pages here. */ - kvm_get_pfn(pfn); + if (!kvm_try_get_pfn(pfn)) + r = -EFAULT; out: pte_unmap_unlock(ptep, ptl); *p_pfn = pfn; - return 0; + + return r; } /* |