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lmkd: remove priority setting for the kill target 

Setting cpusets and priorities for the kill target involves fs operations
which can block on kernel internal locks. Doing that from lmkd main thread
context has the danger of blocking lmkd. With the introduction of the
reaper threads the time for the target to exit is not as critical since
its memory is freed by the reaper thread.
To prevent lmkd from being blocked, move setting cpuset for the kill
target into the reaper thread and remove priority setting logic with
heavy use of procfs reads.

Bug: 238495258
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I5defc6baa4ff1425d9835371b47a64e375ebac10
This commit is contained in:
Suren Baghdasaryan 2022-10-04 13:40:24 -07:00
parent 495db5c643
commit 67c467d4ec
1 changed files with 8 additions and 39 deletions
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47
reaper.cpp
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@ -89,6 +89,14 @@ static void* reaper_main(void* param) {
ALOGI("Process %d was reaped in %ldms", target.pid,
get_time_diff_ms(&start_tm, &end_tm));
}
if (!SetProcessProfilesCached(target.uid, target.pid,
{"CPUSET_SP_FOREGROUND", "SCHED_SP_FOREGROUND"})) {
if (reaper->debug_enabled()) {
ALOGW("Failed to set task profiles for the process (%d) being killed", target.pid);
}
}
done:
close(target.pidfd);
reaper->request_complete();
@ -152,41 +160,6 @@ bool Reaper::init(int comm_fd) {
return true;
}
static void set_process_group_and_prio(uid_t uid, int pid, const std::vector<std::string>& profiles,
int prio) {
DIR* d;
char proc_path[PATH_MAX];
struct dirent* de;
if (!SetProcessProfilesCached(uid, pid, profiles)) {
ALOGW("Failed to set task profiles for the process (%d) being killed", pid);
}
snprintf(proc_path, sizeof(proc_path), "/proc/%d/task", pid);
if (!(d = opendir(proc_path))) {
ALOGW("Failed to open %s; errno=%d: process pid(%d) might have died", proc_path, errno,
pid);
return;
}
while ((de = readdir(d))) {
int t_pid;
if (de->d_name[0] == '.') continue;
t_pid = atoi(de->d_name);
if (!t_pid) {
ALOGW("Failed to get t_pid for '%s' of pid(%d)", de->d_name, pid);
continue;
}
if (setpriority(PRIO_PROCESS, t_pid, prio) && errno != ESRCH) {
ALOGW("Unable to raise priority of killing t_pid (%d): errno=%d", t_pid, errno);
}
}
closedir(d);
}
bool Reaper::async_kill(const struct target_proc& target) {
if (target.pidfd == -1) {
return false;
@ -210,10 +183,6 @@ bool Reaper::async_kill(const struct target_proc& target) {
cond_.notify_one();
mutex_.unlock();
set_process_group_and_prio(target.uid, target.pid,
{"CPUSET_SP_FOREGROUND", "SCHED_SP_FOREGROUND"},
ANDROID_PRIORITY_HIGHEST);
return true;
}