The patch titled Subject: mm/khugepaged: collapse_shmem() stop if punched or truncated has been added to the -mm tree. Its filename is mm-khugepaged-collapse_shmem-stop-if-punched-or-truncated.patch

This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-khugepaged-collapse_shmem-stop-i... and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-khugepaged-collapse_shmem-stop-i...

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------------------------------------------------------ From: Hugh Dickins hughd@google.com Subject: mm/khugepaged: collapse_shmem() stop if punched or truncated

Huge tmpfs testing showed that although collapse_shmem() recognizes a concurrently truncated or hole-punched page correctly, its handling of holes was liable to refill an emptied extent. Add check to stop that.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261522040.2275@eggly.anvils Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages") Signed-off-by: Hugh Dickins hughd@google.com Reviewed-by: Matthew Wilcox willy@infradead.org Cc: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: Jerome Glisse jglisse@redhat.com Cc: Konstantin Khlebnikov khlebnikov@yandex-team.ru Cc: stable@vger.kernel.org [4.8+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

--- a/mm/khugepaged.c~mm-khugepaged-collapse_shmem-stop-if-punched-or-truncated +++ a/mm/khugepaged.c @@ -1359,6 +1359,17 @@ static void collapse_shmem(struct mm_str

VM_BUG_ON(index != xas.xa_index); if (!page) { + /* + * Stop if extent has been truncated or hole-punched, + * and is now completely empty. + */ + if (index == start) { + if (!xas_next_entry(&xas, end - 1)) { + result = SCAN_TRUNCATED; + break; + } + xas_set(&xas, index); + } if (!shmem_charge(mapping->host, 1)) { result = SCAN_FAIL; break; _

Patches currently in -mm which might be from hughd@google.com are

mm-huge_memory-rename-freeze_page-to-unmap_page.patch mm-huge_memory-splitting-set-mappingindex-before-unfreeze.patch mm-huge_memory-fix-lockdep-complaint-on-32-bit-i_size_read.patch mm-khugepaged-collapse_shmem-stop-if-punched-or-truncated.patch mm-khugepaged-fix-crashes-due-to-misaccounted-holes.patch mm-khugepaged-collapse_shmem-remember-to-clear-holes.patch mm-khugepaged-minor-reorderings-in-collapse_shmem.patch mm-khugepaged-collapse_shmem-without-freezing-new_page.patch mm-khugepaged-collapse_shmem-do-not-crash-on-compound.patch mm-khugepaged-fix-the-xas_create_range-error-path.patch mm-put_and_wait_on_page_locked-while-page-is-migrated.patch