Messages in this thread Patch in this message |  | | From | liuqiangneo@163 ... | | Subject | [PATCH v2] lib/test_hmm: Check alloc_page_vma() return value | | Date | Mon, 18 May 2026 11:19:03 +0800 |
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From: Qiang Liu <liuqiang@kylinos.cn>
Return VM_FAULT_OOM if page allocation fails, which avoids a NULL pointer dereference when calling lock_page().
Signed-off-by: Qiang Liu <liuqiang@kylinos.cn> --- v2: - Add unlock and free allocated pages before return. - https://lore.kernel.org/all/20260514032345.32256-1-liuqiangneo@163.com/ --- lib/test_hmm.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/lib/test_hmm.c b/lib/test_hmm.c index 213504915737..90aec4ca2e01 100644 --- a/lib/test_hmm.c +++ b/lib/test_hmm.c @@ -1063,6 +1063,17 @@ static vm_fault_t dmirror_devmem_fault_alloc_and_copy(struct migrate_vma *args, /* Try with smaller pages if large allocation fails */ if (!dpage && order) { dpage = alloc_page_vma(GFP_HIGHUSER_MOVABLE, args->vma, addr); + if (!dpage) { + /* Unlock and free pages already allocated. */ + while (i > 0) { + struct page *fpage; + + fpage = migrate_pfn_to_page(dst[--i]); + unlock_page(fpage); + __free_page(fpage); + } + return VM_FAULT_OOM; + } lock_page(dpage); dst[i] = migrate_pfn(page_to_pfn(dpage)); dst_page = pfn_to_page(page_to_pfn(dpage)); -- 2.43.0
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