On Tue, 15 Feb 2022 07:37:43 +0000 cgel.zte@xxxxxxxxx wrote:
> From: wangyong <wang.yong12@xxxxxxxxxx>
>
> After enabling tmpfs filesystem to support transparent hugepage with the
> following command:
> echo always > /sys/kernel/mm/transparent_hugepage/shmem_enabled
> The docker program adds F_SEAL_WRITE through the following command will
> prompt EBUSY.
> fcntl(5, F_ADD_SEALS, F_SEAL_WRITE)=-1.
>
> It is found that in memfd_wait_for_pins function, the page_count of
> hugepage is 512 and page_mapcount is 0, which does not meet the
> conditions:
> page_count(page) - page_mapcount(page) != 1.
> But the page is not busy at this time, therefore, the page_order of
> hugepage should be taken into account in the calculation.
What are the real-world runtime effects of this?
Do we think that this fix (or one similar to it) should be backported
into -stable kernels?
If "yes" then Mike's 5d752600a8c373 ("mm: restructure memfd code") will
get in the way because it moved lots of code around.
But then, that's four years old and perhaps that's far enough back in
time.
