Messages in this thread | | | Date | Mon, 27 Oct 2008 11:58:04 -0400 | From | Oren Laadan <> | Subject | Re: [PATCH 10/10] Add support for multiple processes |
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Andrey Mirkin wrote: > The whole tree of processes can be checkpointed and restarted now. > Shared objects are not supported yet. > > Signed-off-by: Andrey Mirkin <major@openvz.org> > --- > checkpoint/cpt_image.h | 2 + > checkpoint/cpt_process.c | 24 +++++++++++++ > checkpoint/rst_process.c | 85 +++++++++++++++++++++++++++------------------- > 3 files changed, 76 insertions(+), 35 deletions(-) > > diff --git a/checkpoint/cpt_image.h b/checkpoint/cpt_image.h > index e1fb483..f370df2 100644 > --- a/checkpoint/cpt_image.h > +++ b/checkpoint/cpt_image.h > @@ -128,6 +128,8 @@ struct cpt_task_image { > __u64 cpt_nivcsw; > __u64 cpt_min_flt; > __u64 cpt_maj_flt; > + __u32 cpt_children_num; > + __u32 cpt_pad; > } __attribute__ ((aligned (8))); > > struct cpt_mm_image { > diff --git a/checkpoint/cpt_process.c b/checkpoint/cpt_process.c > index 1f7a54b..d73ec3c 100644 > --- a/checkpoint/cpt_process.c > +++ b/checkpoint/cpt_process.c > @@ -40,6 +40,19 @@ static unsigned int encode_task_flags(unsigned int task_flags) > > } > > +static int cpt_count_children(struct task_struct *tsk, struct cpt_context *ctx) > +{ > + int num = 0; > + struct task_struct *child; > + > + list_for_each_entry(child, &tsk->children, sibling) { > + if (child->parent != tsk) > + continue; > + num++; > + } > + return num; > +} > +
I noticed that don't take the appropriate locks when browsing through tasks lists (siblings, children, global list). Although I realize that the container should be frozen at this time, I keep wondering if this is indeed always safe.
For instance, are you protected against an OOM killer that might just occur uninvited and kill one of those tasks ?
Can the administrator force an un-freeze of the container ? Or perhaps some error condition if the kernel cause that ?
> int cpt_dump_task_struct(struct task_struct *tsk, struct cpt_context *ctx) > { > struct cpt_task_image *t; > @@ -102,6 +115,7 @@ int cpt_dump_task_struct(struct task_struct *tsk, struct cpt_context *ctx) > t->cpt_egid = tsk->egid; > t->cpt_sgid = tsk->sgid; > t->cpt_fsgid = tsk->fsgid; > + t->cpt_children_num = cpt_count_children(tsk, ctx); > > err = ctx->write(t, sizeof(*t), ctx); > > @@ -231,6 +245,16 @@ int cpt_dump_task(struct task_struct *tsk, struct cpt_context *ctx) > err = cpt_dump_fpustate(tsk, ctx); > if (!err) > err = cpt_dump_registers(tsk, ctx); > + if (!err) { > + struct task_struct *child; > + list_for_each_entry(child, &tsk->children, sibling) { > + if (child->parent != tsk) > + continue; > + err = cpt_dump_task(child, ctx); > + if (err) > + break;
Here too.
[...]
Oren.
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