adbd: increase oom_score_adj for `adb shell`
Previously, processes started via `adb shell` have an oom_score_adj of
-1000, making them invisible to the oom killer. This makes running a
process that consumes all memory (e.g. by leaking in a loop) lead to
the entire rest of the system (including adbd, because of bad
heuristics in the kernel) being oom killed before getting to it.
Bug: http://b/63143027
Test: `adb shell cat /proc/self/oom_score_adj` with adb root
Change-Id: I59111134e36dc271adf4c1dd4bd4400d4fe6aee0
(cherry picked from commit 2de2ade387774effee209a1498f16babab81e4ee)
diff --git a/adb/shell_service.cpp b/adb/shell_service.cpp
index 17c7eba..da1222b 100644
--- a/adb/shell_service.cpp
+++ b/adb/shell_service.cpp
@@ -334,6 +334,15 @@
// processes, so we need to manually reset back to SIG_DFL here (http://b/35209888).
signal(SIGPIPE, SIG_DFL);
+ // Increase oom_score_adj from -1000, so that the child is visible to the OOM-killer.
+ // Don't treat failure as an error, because old Android kernels explicitly disabled this.
+ int oom_score_adj_fd = adb_open("/proc/self/oom_score_adj", O_WRONLY | O_CLOEXEC);
+ if (oom_score_adj_fd != -1) {
+ const char* oom_score_adj_value = "-950";
+ TEMP_FAILURE_RETRY(
+ adb_write(oom_score_adj_fd, oom_score_adj_value, strlen(oom_score_adj_value)));
+ }
+
if (command_.empty()) {
execle(_PATH_BSHELL, _PATH_BSHELL, "-", nullptr, cenv.data());
} else {