On Sun, Apr 18, 2021 at 03:10:25PM +0300, Gal Pressman wrote:
> The new attribute indicates that the kernel copies DMA pages on fork,
> hence libibverbs' fork support through madvise and MADV_DONTFORK is not
> needed.
>
> The introduced attribute is always reported as supported since the
> kernel has the patch that added the copy-on-fork behavior. This allows
> the userspace library to identify older vs newer kernel versions.
> Extra care should be taken when backporting this patch as it relies on
> the fact that the copy-on-fork patch is merged, hence no check for
> support is added.
>
> Don't backport this patch unless you also have the following series:
> 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes")
> and 4eae4efa2c29 ("hugetlb: do early cow when page pinned on src mm").
>
> Fixes: 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes")
> Fixes: 4eae4efa2c29 ("hugetlb: do early cow when page pinned on src mm")
> Signed-off-by: Gal Pressman <galpress@xxxxxxxxxx>
> Reviewed-by: Leon Romanovsky <leonro@xxxxxxxxxx>
> ---
> PR was sent:
> https://github.com/linux-rdma/rdma-core/pull/975
>
> Changelog -
> v3->v4: https://lore.kernel.org/linux-rdma/20210412064150.40064-1-galpress@xxxxxxxxxx/
> * Mention that nla_put_u8() return value is ignored on purpose
>
> v2->v3: https://lore.kernel.org/linux-rdma/21317d2c-9a8e-0dd7-3678-d2933c5053c4@xxxxxxxxxx/
> * Remove check if copy-on-fork attribute was provided from nldev_set_sys_set_doit()
>
> v1->v2: https://lore.kernel.org/linux-rdma/20210405114722.98904-1-galpress@xxxxxxxxxx/
> * Remove nla_put_u8() return value check
> * Add commit hashes to commit message and code comment
> ---
> drivers/infiniband/core/nldev.c | 14 ++++++++++++++
> include/uapi/rdma/rdma_netlink.h | 2 ++
> 2 files changed, 16 insertions(+)
Applied to for-next, not the enum number will have changed compared to
what you sent
Thanks,
Jason
