[CRIU] [PATCH v5 3/5] Try to include userfaultfd with criu (part 1)

[Adrian Reber]

On Thu, Mar 10, 2016 at 03:06:06PM +0300, Dmitry Safonov wrote:
> On 03/10/2016 10:39 AM, Adrian Reber wrote:
[...]
> >v5:
> >     * split the userfaultfd patch in multiple smaller patches
> >     * introduced vma_can_be_lazy() function to check if a page
> >       can be handled by uffd
> >     * moved uffd related code from cr-restore.c to uffd.c
> >     * handle failure to register a memory page of the restored process
> >       with userfaultfd
> Hello, Adrian,
> just a small nip from me below:
> >
> >Signed-off-by: Adrian Reber <areber at redhat.com>
> >---
> >  criu/Makefile.config      |   6 +-
> >  criu/Makefile.crtools     |   4 +
> >  criu/crtools.c            |   6 +
> >  criu/include/crtools.h    |   5 +
> >  criu/include/uffd.h       |  16 ++
> >  criu/uffd.c               | 437 ++++++++++++++++++++++++++++++++++++++++++++++
> >  scripts/feature-tests.mak |  15 ++
> >  7 files changed, 488 insertions(+), 1 deletion(-)
> >  create mode 100644 criu/include/uffd.h
> >  create mode 100644 criu/uffd.c
> >
> >diff --git a/criu/Makefile.config b/criu/Makefile.config
> >index aaaca1f..c3841b9 100644
> >--- a/criu/Makefile.config
> >+++ b/criu/Makefile.config
> >@@ -14,8 +14,12 @@ ifeq ($(call pkg-config-check,libselinux),y)
> >          DEFINES	+= -DCONFIG_HAS_SELINUX
> >  endif
> >+ifeq ($(call try-cc,$(FEATURE_TEST_UFFD)),y)
> >+	export UFFD := 1
> >+endif
> >+
> Here we try-cc feature test,
> >  FEATURES_LIST	:= TCP_REPAIR PRLIMIT STRLCPY STRLCAT PTRACE_PEEKSIGINFO \
> >-	SETPROCTITLE_INIT MEMFD
> >+	SETPROCTITLE_INIT MEMFD UFFD
> and adding it to FEATURES_LIST will compile feature test for CONFIG_HAS_*
> define the second time, which will slowdown makefile processing.
> As we know the result of first try-cc, we may use it (completely untested):
> 
> diff --git a/criu/Makefile.config b/criu/Makefile.config
> index c3841b9..56076b6 100644
> --- a/criu/Makefile.config
> +++ b/criu/Makefile.config
> @@ -19,7 +19,7 @@ ifeq ($(call try-cc,$(FEATURE_TEST_UFFD)),y)
>  endif
> 
>  FEATURES_LIST  := TCP_REPAIR PRLIMIT STRLCPY STRLCAT PTRACE_PEEKSIGINFO \
> -       SETPROCTITLE_INIT MEMFD UFFD
> +       SETPROCTITLE_INIT MEMFD
> 
>  # $1 - config name
>  define gen-feature-test
> @@ -38,6 +38,10 @@ $(CONFIG_HEADER): include/config-base.h
>         $(Q) @echo '#include "config-base.h"'                           >>
> $$@
>         $(Q) @echo ''                                                   >>
> $$@
>  $(call map,gen-feature-test,$(FEATURES_LIST))
> +ifeq ($$(UFFD),1)
> +       $(Q) @echo '#define CONFIG_HAS_UFFD'                            >>
> $$@
> +       $(Q) @echo ''                                                   >>
> $$@
> +endif
>  ifeq ($$(VDSO),y)
>         $(Q) @echo '#define CONFIG_VDSO'                                >>
> $$@
>         $(Q) @echo ''                                                   >>
> $$@
> 
> Through, slowdown will not be great (exec+cc a small program) - you
> may drop this and I'm fine.
> Maybe if we'll have more feature test that need Makefile define exports,
> we'll make some standard for makefile variables like $(UFFD) and
> clean this, but yet, I suggest adding this diff.

No problem, I will include this change in the next re-spin. Actually,
that was the implementation I had in the beginning until I found the
FEATURES_LIST functionality. Before re-sending the patches I am waiting
for further comments from Pavel.

		Adrian