[CRIU] [PATCH 2/5] kdat: Relax uffd checks (v2)

[Mike Rapoport]

On Wed, Apr 26, 2017 at 10:46:52PM +0300, Pavel Emelyanov wrote:
> v2: When uffd is present, the reported features may still be 0,
>     so we need one more bool for uffd syscall itself.
> 
> Signed-off-by: Pavel Emelyanov <xemul at virtuozzo.com>

Acked-by: Mike Rapoport <rppt at linux.vnet.ibm.com>

> ---
>  criu/cr-check.c        |  7 ++++++-
>  criu/cr-service.c      |  4 ++--
>  criu/include/kerndat.h |  3 ++-
>  criu/kerndat.c         | 10 ++++++----
>  criu/uffd.c            |  2 +-
>  5 files changed, 17 insertions(+), 9 deletions(-)
> 
> diff --git a/criu/cr-check.c b/criu/cr-check.c
> index 8d13504..0fcb285 100644
> --- a/criu/cr-check.c
> +++ b/criu/cr-check.c
> @@ -1075,9 +1075,14 @@ static int check_uffd(void)
>  		UFFD_FEATURE_EVENT_UNMAP |
>  		UFFD_FEATURE_EVENT_REMOVE;
> 
> -	if (kerndat_uffd(true))
> +	if (kerndat_uffd())
>  		return -1;
> 
> +	if (!kdat.has_uffd) {
> +		pr_err("UFFD is not supported\n");
> +		return -1;
> +	}
> +
>  	if ((kdat.uffd_features & features) != features) {
>  		pr_err("Userfaultfd missing essential features\n");
>  		return -1;
> diff --git a/criu/cr-service.c b/criu/cr-service.c
> index d59ab8b..8cf76dd 100644
> --- a/criu/cr-service.c
> +++ b/criu/cr-service.c
> @@ -893,7 +893,7 @@ static int handle_feature_check(int sk, CriuReq * msg)
> 
>  		if ((msg->features->has_lazy_pages == 1) &&
>  		    (msg->features->lazy_pages == true)) {
> -			ret = kerndat_uffd(true);
> +			ret = kerndat_uffd();
> 
>  			/*
>  			 * Not checking for specific UFFD features yet.
> @@ -902,7 +902,7 @@ static int handle_feature_check(int sk, CriuReq * msg)
>  			 * be extended in the future for a more detailed
>  			 * UFFD feature check.
>  			 */
> -			if (ret)
> +			if (ret || !kdat.has_uffd)
>  				feat.lazy_pages = false;
>  			else
>  				feat.lazy_pages = true;
> diff --git a/criu/include/kerndat.h b/criu/include/kerndat.h
> index b8508ff..e6eb395 100644
> --- a/criu/include/kerndat.h
> +++ b/criu/include/kerndat.h
> @@ -45,6 +45,7 @@ struct kerndat_s {
>  	unsigned int has_xtlocks;
>  	unsigned long mmap_min_addr;
>  	bool has_tcp_half_closed;
> +	bool has_uffd;
>  	unsigned long uffd_features;
>  	bool has_nsid;
>  	bool has_link_nsid;
> @@ -70,7 +71,7 @@ enum {
>  extern int kerndat_fs_virtualized(unsigned int which, u32 kdev);
> 
>  extern int kerndat_tcp_repair();
> -extern int kerndat_uffd(bool need_uffd);
> +extern int kerndat_uffd(void);
>  extern int kerndat_has_nspid(void);
> 
>  #endif /* __CR_KERNDAT_H__ */
> diff --git a/criu/kerndat.c b/criu/kerndat.c
> index 9c47b13..96c969a 100644
> --- a/criu/kerndat.c
> +++ b/criu/kerndat.c
> @@ -586,7 +586,7 @@ static int kerndat_compat_restore(void)
>  	return 0;
>  }
> 
> -int kerndat_uffd(bool need_uffd)
> +int kerndat_uffd(void)
>  {
>  	struct uffdio_api uffdio_api;
>  	int uffd;
> @@ -598,14 +598,16 @@ int kerndat_uffd(bool need_uffd)
>  	 * on this system. Additionally checking for ENOSYS
>  	 * makes sure it is actually not implemented.
>  	 */
> -	if (uffd == -1 && errno == ENOSYS) {
> -		if (!need_uffd)
> +	if (uffd == -1) {
> +		if (errno == ENOSYS)
>  			return 0;
> 
>  		pr_err("Lazy pages are not available\n");
>  		return -1;
>  	}
> 
> +	kdat.has_uffd = true;
> +
>  	uffdio_api.api = UFFD_API;
>  	uffdio_api.features = 0;
>  	if (ioctl(uffd, UFFDIO_API, &uffdio_api)) {
> @@ -718,7 +720,7 @@ int kerndat_init_rst(void)
>  	if (!ret)
>  		ret = kerndat_compat_restore();
>  	if (!ret)
> -		ret = kerndat_uffd(opts.lazy_pages);
> +		ret = kerndat_uffd();
>  	if (!ret)
>  		ret = kerndat_socket_netns();
>  	if (!ret)
> diff --git a/criu/uffd.c b/criu/uffd.c
> index b2cf102..205045e 100644
> --- a/criu/uffd.c
> +++ b/criu/uffd.c
> @@ -1115,7 +1115,7 @@ int cr_lazy_pages(bool daemon)
>  	int lazy_sk;
>  	int ret;
> 
> -	if (kerndat_uffd(true))
> +	if (kerndat_uffd() || !kdat.has_uffd)
>  		return -1;
> 
>  	if (prepare_dummy_pstree())
> -- 
> 2.5.5
> 
> _______________________________________________
> CRIU mailing list
> CRIU at openvz.org
> https://lists.openvz.org/mailman/listinfo/criu
>