i'm not finding any code that has a string "SLAB INFO" or "/proc/slabinfo", so i have no idea where that's coming from.  debugd doesn't provide it.

as for why it's failing, my guess is it's not running as root, and our perms are blocking it (by design):
-r--------. 1 root root 0 Apr  3 16:45 /proc/slabinfo

so whatever is generating that system_logs.zip should be updated to use debugd instead of trying to read random files in /proc/ itself.

I think it might be the ARC++ side of things.  Maybe yusukes@ knows?

Yes this is ARC++ side, and I think that's the problem. Although the 'bugreport' command which runs inside the container and writes the 'Permission denied' output runs as root (I believe), it still cannot read the /proc entry because 'root' inside the container is not really the real root. (dgreid@: please correct me if I'm wrong.)

If we need the info, I think we need to read the /proc entry directly from Chrome OS debugd and include it in the feedback report.

Correct, proc mounted from inside a pid namespace doesn't give the unprivileged root user access to everything.

slabinfo seems like something we need to read as real root from debugd.

c#3 and c#4 make sense to me.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform2/+/34171bac8a4837733407019d195b0ffa8e60b2d6

commit 34171bac8a4837733407019d195b0ffa8e60b2d6
Author: yusukes <yusukes@google.com>
Date: Wed May 03 03:24:16 2017

debugd: Add 'cat /proc/slabinfo' to common_logs

The output will be included in both chrome://system and the feedback
log.

BUG= chromium:707901 
TEST=chrome://system has the entry

Change-Id: Ic4db34936dd7f7d1e2849f2f96e8474d30917b77
Reviewed-on: https://chromium-review.googlesource.com/492566
Commit-Ready: Yusuke Sato <yusukes@chromium.org>
Tested-by: Yusuke Sato <yusukes@chromium.org>
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>

[modify] https://crrev.com/34171bac8a4837733407019d195b0ffa8e60b2d6/debugd/src/log_tool.cc

Verified on build 9534.0.0