The patch titled
Subject: mm/pgtable-generic.c: optimize the VM_BUG_ON condition in pmdp_huge_clear_flush()
has been added to the -mm tree. Its filename is
mm-pgtable-genericc-optimize-the-vm_bug_on-condition-in-pmdp_huge_clear_flush.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-pgtable-genericc-optimize-the-vm_bug_on-condition-in-pmdp_huge_clear_flush.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-pgtable-genericc-optimize-the-vm_bug_on-condition-in-pmdp_huge_clear_flush.patch
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------------------------------------------------------
From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/pgtable-generic.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/mm/pgtable-generic.c~mm-pgtable-genericc-optimize-the-vm_bug_on-condition-in-pmdp_huge_clear_flush
+++ a/mm/pgtable-generic.c
@@ -135,8 +135,9 @@ pmd_t pmdp_huge_clear_flush(struct vm_ar
{
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;
_
Patches currently in -mm which might be from linmiaohe@xxxxxxxxxx are
mm-rmap-fix-potential-pte_unmap-on-an-not-mapped-pte.patch
mm-page_owner-use-helper-function-zone_end_pfn-to-get-end_pfn.patch
mm-fix-potential-pte_unmap_unlock-pte-error.patch
mm-simplify-the-vm_bug_on-condition-in-pmdp_huge_clear_flush.patch
mm-pgtable-genericc-optimize-the-vm_bug_on-condition-in-pmdp_huge_clear_flush.patch
mm-hugetlb-fix-potential-double-free-in-hugetlb_register_node-error-path.patch
mm-hugetlb-avoid-unnecessary-hugetlb_acct_memory-call.patch
mm-hugetlb-use-helper-huge_page_order-and-pages_per_huge_page.patch
mm-hugetlb-fix-use-after-free-when-subpool-max_hpages-accounting-is-not-enabled.patch
mm-hugetlb-fix-some-comment-typos.patch
mm-remove-unused-return-value-of-set_huge_zero_page.patch
mm-workingsetc-avoid-unnecessary-max_nodes-estimation-in-count_shadow_nodes.patch
z3fold-remove-unused-attribute-for-release_z3fold_page.patch
z3fold-simplify-the-zhdr-initialization-code-in-init_z3fold_page.patch
mm-compaction-remove-duplicated-vm_bug_on_page-pagelocked.patch
mm-mempolicy-use-helper-range_in_vma-in-queue_pages_test_walk.patch
hugetlbfs-remove-useless-bug_oninode-in-hugetlbfs_setattr.patch
hugetlbfs-use-helper-macro-default_hstate-in-init_hugetlbfs_fs.patch
hugetlbfs-correct-obsolete-function-name-in-hugetlbfs_read_iter.patch
hugetlbfs-remove-meaningless-variable-avoid_reserve.patch
hugetlbfs-make-hugepage-size-conversion-more-readable.patch
hugetlbfs-correct-some-obsolete-comments-about-inode-i_mutex.patch
hugetlbfs-fix-some-comment-typos.patch
mm-memory_hotplug-use-helper-function-zone_end_pfn-to-get-end_pfn.patch
mm-rmap-correct-some-obsolete-comments-of-anon_vma.patch
mm-rmap-remove-unneeded-semicolon-in-page_not_mapped.patch
mm-rmap-fix-obsolete-comment-in-__page_check_anon_rmap.patch
mm-rmap-use-page_not_mapped-in-try_to_unmap.patch
mm-rmap-correct-obsolete-comment-of-page_get_anon_vma.patch
mm-zsmallocc-convert-to-use-kmem_cache_zalloc-in-cache_alloc_zspage.patch
mm-zsmallocc-use-page_private-to-access-page-private.patch
