Commit ef161cca authored Jun 24, 2021 by Hugh Dickins Committed by Sasha Levin Jun 30, 2021

mm: page_vma_mapped_walk(): use pmde for *pvmw->pmd

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 49611602

mm/page_vma_mapped.c

+6 −5

Original line number	Diff line number	Diff line
		@@ -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);