diff options
| -rw-r--r-- | mm/memfd_luo.c | 25 |
1 files changed, 23 insertions, 2 deletions
diff --git a/mm/memfd_luo.c b/mm/memfd_luo.c index 785f26aa58c0..71d64bcc9c2b 100644 --- a/mm/memfd_luo.c +++ b/mm/memfd_luo.c @@ -152,10 +152,31 @@ static int memfd_luo_preserve_folios(struct file *file, if (err) goto err_unpreserve; + folio_lock(folio); + if (folio_test_dirty(folio)) flags |= MEMFD_LUO_FOLIO_DIRTY; - if (folio_test_uptodate(folio)) - flags |= MEMFD_LUO_FOLIO_UPTODATE; + + /* + * If the folio is not uptodate, it was fallocated but never + * used. Saving this flag at prepare() doesn't work since it + * might change later when someone uses the folio. + * + * Since we have taken the performance penalty of allocating, + * zeroing, and pinning all the folios in the holes, take a bit + * more and zero all non-uptodate folios too. + * + * NOTE: For someone looking to improve preserve performance, + * this is a good place to look. + */ + if (!folio_test_uptodate(folio)) { + folio_zero_range(folio, 0, folio_size(folio)); + flush_dcache_folio(folio); + folio_mark_uptodate(folio); + } + flags |= MEMFD_LUO_FOLIO_UPTODATE; + + folio_unlock(folio); pfolio->pfn = folio_pfn(folio); pfolio->flags = flags; |