| Message ID | 1443544494-28737-7-git-send-email-marcandre.lureau@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Tue, Sep 29, 2015 at 06:34:36PM +0200, marcandre.lureau@redhat.com wrote: > From: Marc-André Lureau <marcandre.lureau@redhat.com> > > Add an open/unlink/mmap fallback for system that do not support memfd. > This patch may require additional SELinux policies to work for enforced > systems, but should gracefully fail nonetheless. > > Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> I'd rather just fail migration. > --- > util/memfd.c | 22 ++++++++++++++++++++-- > 1 file changed, 20 insertions(+), 2 deletions(-) > > diff --git a/util/memfd.c b/util/memfd.c > index 3168902..970b5b0 100644 > --- a/util/memfd.c > +++ b/util/memfd.c > @@ -84,8 +84,26 @@ void *qemu_memfd_alloc(const char *name, size_t size, unsigned int seals, > return NULL; > } > } else { > - perror("memfd"); > - return NULL; > + const char *tmpdir = getenv("TMPDIR"); > + gchar *fname; > + > + tmpdir = tmpdir ? tmpdir : "/tmp"; > + > + fname = g_strdup_printf("%s/memfd-XXXXXX", tmpdir); > + mfd = mkstemp(fname); > + unlink(fname); > + g_free(fname); > + > + if (mfd == -1) { > + perror("mkstemp"); > + return NULL; > + } > + > + if (ftruncate(mfd, size) == -1) { > + perror("ftruncate"); > + close(mfd); > + return NULL; > + } > } > > ptr = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, mfd, 0); > -- > 2.4.3
Hi ----- Original Message ----- > On Tue, Sep 29, 2015 at 06:34:36PM +0200, marcandre.lureau@redhat.com wrote: > > From: Marc-André Lureau <marcandre.lureau@redhat.com> > > > > Add an open/unlink/mmap fallback for system that do not support memfd. > > This patch may require additional SELinux policies to work for enforced > > systems, but should gracefully fail nonetheless. > > > > Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> > > I'd rather just fail migration. So we don't provide this compatibility code and migration should fail. Would it be enough to check if memfd works at early runtime and add a migration blocker for vhost-user? Or is it possible to recover if migration fails when memfd fails to allocate? I would thing the former is better. > > > --- > > util/memfd.c | 22 ++++++++++++++++++++-- > > 1 file changed, 20 insertions(+), 2 deletions(-) > > > > diff --git a/util/memfd.c b/util/memfd.c > > index 3168902..970b5b0 100644 > > --- a/util/memfd.c > > +++ b/util/memfd.c > > @@ -84,8 +84,26 @@ void *qemu_memfd_alloc(const char *name, size_t size, > > unsigned int seals, > > return NULL; > > } > > } else { > > - perror("memfd"); > > - return NULL; > > + const char *tmpdir = getenv("TMPDIR"); > > + gchar *fname; > > + > > + tmpdir = tmpdir ? tmpdir : "/tmp"; > > + > > + fname = g_strdup_printf("%s/memfd-XXXXXX", tmpdir); > > + mfd = mkstemp(fname); > > + unlink(fname); > > + g_free(fname); > > + > > + if (mfd == -1) { > > + perror("mkstemp"); > > + return NULL; > > + } > > + > > + if (ftruncate(mfd, size) == -1) { > > + perror("ftruncate"); > > + close(mfd); > > + return NULL; > > + } > > } > > > > ptr = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, mfd, 0); > > -- > > 2.4.3 >
On Wed, Sep 30, 2015 at 05:06:55AM -0400, Marc-André Lureau wrote: > Hi > > ----- Original Message ----- > > On Tue, Sep 29, 2015 at 06:34:36PM +0200, marcandre.lureau@redhat.com wrote: > > > From: Marc-André Lureau <marcandre.lureau@redhat.com> > > > > > > Add an open/unlink/mmap fallback for system that do not support memfd. > > > This patch may require additional SELinux policies to work for enforced > > > systems, but should gracefully fail nonetheless. > > > > > > Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> > > > > I'd rather just fail migration. > > So we don't provide this compatibility code and migration should fail. > > Would it be enough to check if memfd works at early runtime and add a migration blocker for vhost-user? Or is it possible to recover if migration fails when memfd fails to allocate? I would thing the former is better. Fine with me. > > > > > --- > > > util/memfd.c | 22 ++++++++++++++++++++-- > > > 1 file changed, 20 insertions(+), 2 deletions(-) > > > > > > diff --git a/util/memfd.c b/util/memfd.c > > > index 3168902..970b5b0 100644 > > > --- a/util/memfd.c > > > +++ b/util/memfd.c > > > @@ -84,8 +84,26 @@ void *qemu_memfd_alloc(const char *name, size_t size, > > > unsigned int seals, > > > return NULL; > > > } > > > } else { > > > - perror("memfd"); > > > - return NULL; > > > + const char *tmpdir = getenv("TMPDIR"); > > > + gchar *fname; > > > + > > > + tmpdir = tmpdir ? tmpdir : "/tmp"; > > > + > > > + fname = g_strdup_printf("%s/memfd-XXXXXX", tmpdir); > > > + mfd = mkstemp(fname); > > > + unlink(fname); > > > + g_free(fname); > > > + > > > + if (mfd == -1) { > > > + perror("mkstemp"); > > > + return NULL; > > > + } > > > + > > > + if (ftruncate(mfd, size) == -1) { > > > + perror("ftruncate"); > > > + close(mfd); > > > + return NULL; > > > + } > > > } > > > > > > ptr = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, mfd, 0); > > > -- > > > 2.4.3 > >
diff --git a/util/memfd.c b/util/memfd.c index 3168902..970b5b0 100644 --- a/util/memfd.c +++ b/util/memfd.c @@ -84,8 +84,26 @@ void *qemu_memfd_alloc(const char *name, size_t size, unsigned int seals, return NULL; } } else { - perror("memfd"); - return NULL; + const char *tmpdir = getenv("TMPDIR"); + gchar *fname; + + tmpdir = tmpdir ? tmpdir : "/tmp"; + + fname = g_strdup_printf("%s/memfd-XXXXXX", tmpdir); + mfd = mkstemp(fname); + unlink(fname); + g_free(fname); + + if (mfd == -1) { + perror("mkstemp"); + return NULL; + } + + if (ftruncate(mfd, size) == -1) { + perror("ftruncate"); + close(mfd); + return NULL; + } } ptr = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, mfd, 0);