Am Donnerstag, 13. Dezember 2018, 20:20:17 CET schrieb zhangjun:
> Because the PagePrivate() in UBIFS is different meanings,
...has different meanings...
I'll fix up that myself after applying your patch. No need to send a v3.
> alloc_cma() will fail when one dirty page cache located in
> the type of MIGRATE_CMA
>
> If not adjust the 'extra_count' for dirty page,
> ubifs_migrate_page() -> migrate_page_move_mapping() will
> always return -EAGAIN for:
> expected_count += page_has_private(page)
> This causes the migration to fail until the page cache is cleaned
>
> In general, PagePrivate() indicates that buff_head is already bound
> to this page, and at the same time page_count() will also increase.
> But UBIFS set private flag when the cache is dirty, and page_count()
> not increase.
> Therefore, the expected_count of UBIFS is different from the general
> case.
>
> Signed-off-by: zhangjun <openzhangj@xxxxxxxxx>
Fixes: 4ac1c17b2044 ("UBIFS: Implement ->migratepage()")
> ---
> fs/ubifs/file.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
> index 1b78f2e..890dfce 100644
> --- a/fs/ubifs/file.c
> +++ b/fs/ubifs/file.c
> @@ -1480,8 +1480,17 @@ static int ubifs_migrate_page(struct address_space *mapping,
> struct page *newpage, struct page *page, enum migrate_mode mode)
> {
> int rc;
> + int extra_count = 0;
>
> - rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0);
> + /*
> + * UBIFS uses PG_private as marker and does not raise the page counter.
> + * migrate_page_move_mapping() expects a incremented counter if
> + * PG_private is set. Therefore pass -1 as extra_count for this case.
> + */
> + if (page_has_private(page))
> + extra_count = -1;
> + rc = migrate_page_move_mapping(mapping, newpage, page,
> + NULL, mode, extra_count);
> if (rc != MIGRATEPAGE_SUCCESS)
> return rc;
>
Let's wait a few days to give Kirill a chance to review, then I'll apply the patch.
Thanks,
//richard
