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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 <linmiaohe@huawei.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
master
Miaohe Lin 2021-02-24 12:04:39 -08:00 committed by Linus Torvalds
parent c045c72ccd
commit 374437a274
1 changed files with 3 additions and 2 deletions
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5
mm/pgtable-generic.c
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@ -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;