Re: [PATCH] ubifs: Get/put page when changing PG_private

zhangjun
2018-12-15T20:38:54Z

On 2018/12/15 下午11:01, Richard Weinberger wrote:
> The page migration code assumes that a page with PG_private
> set has its page count elevated by 1.
> UBIFS never did this and therefore the migration code was unable
> to migrate some pages owned by UBIFS.
> The lead to situations where the CMA memory allocator failed to
> allocate memory.
>
> Fix this by using get/put_page when changing PG_private.
>
> Cc: <stable@vger.kernel.org>
> Cc: zhangjun <openzhangj@gmail.com>
> Fixes: 4ac1c17b2044 ("UBIFS: Implement ->migratepage()")
> Reported-by: zhangjun <openzhangj@gmail.com>
> Signed-off-by: Richard Weinberger <richard@nod.at>
> ---
> zhangjun,
>
> Please give this patch a try!
>
> Thanks,
> //richard
> ---
> fs/ubifs/file.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
> index 1b78f2e09218..abe940d0767c 100644
> --- a/fs/ubifs/file.c
> +++ b/fs/ubifs/file.c
> @@ -582,6 +582,7 @@ static int ubifs_write_end(struct file *file, struct address_space *mapping,
> }
>
> if (!PagePrivate(page)) {
> + get_page(page);
> SetPagePrivate(page);
> atomic_long_inc(&c->dirty_pg_cnt);
> __set_page_dirty_nobuffers(page);
> @@ -959,6 +960,7 @@ static int do_writepage(struct page *page, int len)
> atomic_long_dec(&c->dirty_pg_cnt);
> ClearPagePrivate(page);
> ClearPageChecked(page);
> + put_page(page);
>
> kunmap(page);
> unlock_page(page);
> @@ -1318,6 +1320,7 @@ static void ubifs_invalidatepage(struct page *page, unsigned int offset,
> atomic_long_dec(&c->dirty_pg_cnt);
> ClearPagePrivate(page);
> ClearPageChecked(page);
> + put_page(page);
> }
>
> int ubifs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
> @@ -1487,6 +1490,8 @@ static int ubifs_migrate_page(struct address_space *mapping,
>
> if (PagePrivate(page)) {
> ClearPagePrivate(page);
> + put_page(page);
> + get_page(newpage);
> SetPagePrivate(newpage);
> }
>
> @@ -1513,6 +1518,7 @@ static int ubifs_releasepage(struct page *page, gfp_t unused_gfp_flags)
> ubifs_assert(c, 0);
> ClearPagePrivate(page);
> ClearPageChecked(page);
> + put_page(page);
> return 1;
> }
>
> @@ -1582,6 +1588,7 @@ static vm_fault_t ubifs_vm_page_mkwrite(struct vm_fault *vmf)
> else {
> if (!PageChecked(page))
> ubifs_convert_page_budget(c);
> + get_page(page);
> SetPagePrivate(page);
> atomic_long_inc(&c->dirty_pg_cnt);
> __set_page_dirty_nobuffers(page);

Hello Richard

After adding your patch,my test did not go wrong.
I think it is ok now.

thanks
//zhangjun