From: Hugh Dickins Date: Fri, 30 Nov 2018 22:10:35 +0000 (-0800) Subject: mm/khugepaged: collapse_shmem() remember to clear holes X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=2af8ff291848cc4b1cce24b6c943394eb2c761e8;p=openwrt%2Fstaging%2Fblogic.git mm/khugepaged: collapse_shmem() remember to clear holes 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 Acked-by: Kirill A. Shutemov Cc: Jerome Glisse Cc: Konstantin Khlebnikov Cc: Matthew Wilcox Cc: [4.8+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 65e82f665c7c..1c402d33547e 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1467,7 +1467,12 @@ xa_unlocked: * Replacing old pages with new one has succeeded, now we * need to copy the content and free the 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); @@ -1477,6 +1482,11 @@ xa_unlocked: ClearPageActive(page); ClearPageUnevictable(page); put_page(page); + index++; + } + while (index < end) { + clear_highpage(new_page + (index % HPAGE_PMD_NR)); + index++; } local_irq_disable();