From: Miaohe Lin Date: Wed, 24 Feb 2021 20:04:39 +0000 (-0800) Subject: mm/pgtable-generic.c: optimize the VM_BUG_ON condition in pmdp_huge_clear_flush() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=374437a274e24e8e3ccd19f704e80d325f75f254;p=linux.git mm/pgtable-generic.c: optimize the VM_BUG_ON condition in pmdp_huge_clear_flush() The developer will have trouble figuring out why the BUG actually triggered when there is a complex expression in the VM_BUG_ON. Because we can only identify the condition triggered BUG via line number provided by VM_BUG_ON. Optimize this by spliting such a complex expression into two simple conditions. Link: https://lkml.kernel.org/r/20210203084137.25522-1-linmiaohe@huawei.com Signed-off-by: Miaohe Lin Suggested-by: Andrew Morton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c index fa1375f3e3b24..c2210e1cdb515 100644 --- a/mm/pgtable-generic.c +++ b/mm/pgtable-generic.c @@ -135,8 +135,9 @@ pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address, { pmd_t pmd; VM_BUG_ON(address & ~HPAGE_PMD_MASK); - VM_BUG_ON(!pmd_present(*pmdp) || (!pmd_trans_huge(*pmdp) && - !pmd_devmap(*pmdp))); + VM_BUG_ON(!pmd_present(*pmdp)); + /* Below assumes pmd_present() is true */ + VM_BUG_ON(!pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp)); pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp); flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); return pmd;