Oops ...already patched and pushed as per our discussion on IRC.
The patch is functionally identical but adds a comment.
Oren.
Serge E. Hallyn wrote:
> In the case of a restart of a subtree checkpoint, some sids
> may be recorded as 0. If so, then we substitute the coordinator's
> sid. The code to do that wasn't quite right, and in fact writes
> past the end of the pids_arr, which happens to be into the
> copy_arr. As a result, the kernel was getting bogus data for
> substituted pids. In my own case that lead to sys_restart()
> waiting on a bogus vpid (in particular, the pid of my bash shell).
>
> Fix that.
>
> Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
> ---
> restart.c | 22 ++++++++++++----------
> 1 files changed, 12 insertions(+), 10 deletions(-)
>
> diff --git a/restart.c b/restart.c
> index 20f5055..f0b7862 100644
> --- a/restart.c
> +++ b/restart.c
> @@ -2029,17 +2029,19 @@ static int ckpt_adjust_pids(struct ckpt_ctx *ctx)
> if (ctx->pids_arr[m].vpgid == swap.old)
> ctx->copy_arr[m].vpgid = swap.new;
> }
> + }
>
> - /*
> - * If the task's {sid,pgid} was zeroed out (inside
> - * ckpt_init_tree) then substitute the coordinator's
> - * sid for it now. (This should leave no more 0's in
> - * restart of a subtree-checkpoint).
> - */
> - if (ctx->tasks_arr[n].flags & TASK_ZERO_SID)
> - ctx->pids_arr[m].vsid = coord_sid;
> - if (ctx->tasks_arr[n].flags & TASK_ZERO_PGID)
> - ctx->pids_arr[m].vpgid = coord_sid;
> + /*
> + * If the task's {sid,pgid} was zeroed out (inside
> + * ckpt_init_tree) then substitute the coordinator's
> + * sid for it now. (This should leave no more 0's in
> + * restart of a subtree-checkpoint).
> + */
> + for (m = 0; m < ctx->pids_nr; m++) {
> + if (ctx->tasks_arr[m].flags & TASK_ZERO_SID)
> + ctx->copy_arr[m].vsid = coord_sid;
> + if (ctx->tasks_arr[m].flags & TASK_ZERO_PGID)
> + ctx->copy_arr[m].vpgid = coord_sid;
> }
>
> memcpy(ctx->pids_arr, ctx->copy_arr, len);
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