From: Hugh Dickins hughd@google.com
[ Upstream commit 3306d3119ceacc43ea8b141a73e21fea68eec30c ]
page_vma_mapped_walk() cleanup: re-evaluate pmde after taking lock, then use it in subsequent tests, instead of repeatedly dereferencing pointer.
Link: https://lkml.kernel.org/r/53fbc9d-891e-46b2-cb4b-468c3b19238e@google.com Signed-off-by: Hugh Dickins hughd@google.com Acked-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Reviewed-by: Peter Xu peterx@redhat.com Cc: Alistair Popple apopple@nvidia.com Cc: Matthew Wilcox willy@infradead.org Cc: Ralph Campbell rcampbell@nvidia.com Cc: Wang Yugui wangyugui@e16-tech.com Cc: Will Deacon will@kernel.org Cc: Yang Shi shy828301@gmail.com Cc: Zi Yan ziy@nvidia.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- mm/page_vma_mapped.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index bdb63aafc737..8a6af4007c7e 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -186,18 +186,19 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) pmde = READ_ONCE(*pvmw->pmd); if (pmd_trans_huge(pmde) || is_pmd_migration_entry(pmde)) { pvmw->ptl = pmd_lock(mm, pvmw->pmd); - if (likely(pmd_trans_huge(*pvmw->pmd))) { + pmde = *pvmw->pmd; + if (likely(pmd_trans_huge(pmde))) { if (pvmw->flags & PVMW_MIGRATION) return not_found(pvmw); - if (pmd_page(*pvmw->pmd) != page) + if (pmd_page(pmde) != page) return not_found(pvmw); return true; - } else if (!pmd_present(*pvmw->pmd)) { + } else if (!pmd_present(pmde)) { if (thp_migration_supported()) { if (!(pvmw->flags & PVMW_MIGRATION)) return not_found(pvmw); - if (is_migration_entry(pmd_to_swp_entry(*pvmw->pmd))) { - swp_entry_t entry = pmd_to_swp_entry(*pvmw->pmd); + if (is_migration_entry(pmd_to_swp_entry(pmde))) { + swp_entry_t entry = pmd_to_swp_entry(pmde);
if (migration_entry_to_page(entry) != page) return not_found(pvmw);