4.19-stable review patch. If anyone has any objections, please let me know.
------------------ commit 2af8ff291848cc4b1cce24b6c943394eb2c761e8 upstream. Huge tmpfs testing reminds us that there is no __GFP_ZERO in the gfp flags khugepaged uses to allocate a huge page - in all common cases it would just be a waste of effort - so collapse_shmem() must remember to clear out any holes that it instantiates. The obvious place to do so, where they are put into the page cache tree, is not a good choice: because interrupts are disabled there. Leave it until further down, once success is assured, where the other pages are copied (before setting PageUptodate). Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261525080.2275@eggly.anvils Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages") Signed-off-by: Hugh Dickins <hu...@google.com> Acked-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com> Cc: Jerome Glisse <jgli...@redhat.com> Cc: Konstantin Khlebnikov <khlebni...@yandex-team.ru> Cc: Matthew Wilcox <wi...@infradead.org> Cc: <sta...@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Sasha Levin <sas...@kernel.org> --- mm/khugepaged.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 87dbb0fcfa1a..068868763b78 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1498,7 +1498,12 @@ static void collapse_shmem(struct mm_struct *mm, * Replacing old pages with new one has succeed, now we need to * copy the content and free old pages. */ + index = start; list_for_each_entry_safe(page, tmp, &pagelist, lru) { + while (index < page->index) { + clear_highpage(new_page + (index % HPAGE_PMD_NR)); + index++; + } copy_highpage(new_page + (page->index % HPAGE_PMD_NR), page); list_del(&page->lru); @@ -1508,6 +1513,11 @@ static void collapse_shmem(struct mm_struct *mm, ClearPageActive(page); ClearPageUnevictable(page); put_page(page); + index++; + } + while (index < end) { + clear_highpage(new_page + (index % HPAGE_PMD_NR)); + index++; } local_irq_save(flags); -- 2.17.1
