bpfloader - bump memlock rlimit to 1GiB
Test: build, atest
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I5a1728fe29e510c06978a0c7c5cc90af3e9ea46d
diff --git a/bpfloader/bpfloader.rc b/bpfloader/bpfloader.rc
index 31747fb..4404c17 100644
--- a/bpfloader/bpfloader.rc
+++ b/bpfloader/bpfloader.rc
@@ -1,9 +1,33 @@
service bpfloader /system/bin/bpfloader
class main
capabilities SYS_ADMIN
- # Set RLIMIT_MEMLOCK to 64MB for bpfloader
- # Actually only 8MB is needed, but since bpfloader runs as root, it shares
- # the global rlimit. Once bpfloader is running as its own user in the
- # future, it will have dedicated rlimit to itself and this can be 8MB.
- rlimit memlock 67108864 67108864
+ #
+ # Set RLIMIT_MEMLOCK to 1GiB for bpfloader
+ #
+ # Actually only 8MiB would be needed if bpfloader ran as its own uid.
+ #
+ # However, while the rlimit is per-thread, the accounting is system wide.
+ # So, for example, if the graphics stack has already allocated 10MiB of
+ # memlock data before bpfloader even gets a chance to run, it would fail
+ # if its memlock rlimit is only 8MiB - since there would be none left for it.
+ #
+ # bpfloader succeeding is critical to system health, since a failure will
+ # cause netd crashloop and thus system server crashloop... and the only
+ # recovery is a full kernel reboot.
+ #
+ # We've had issues where devices would sometimes (rarely) boot into
+ # a crashloop because bpfloader would occasionally lose a boot time
+ # race against the graphics stack's boot time locked memory allocation.
+ #
+ # Thus bpfloader's memlock has to be 8MB higher then the locked memory
+ # consumption of the root uid anywhere else in the system...
+ # But we don't know what that is for all possible devices...
+ #
+ # Ideally, we'd simply grant bpfloader the IPC_LOCK capability and it
+ # would simply ignore it's memlock rlimit... but it turns that this
+ # capability is not even checked by the kernel's bpf system call.
+ #
+ # As such we simply use 1GiB as a reasonable approximation of infinity.
+ #
+ rlimit memlock 1073741824 1073741824
oneshot