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lmkd: Suppress error when accessing soft_limit_in_bytes for system_server 

system_server needs to register with lmkd, however it has no memory
cgroup under /dev/memcg/apps. This change detects if the process being
registered is system_server and suppresses the error message when
/dev/memcg/apps/uid_%d/pid_%d/memory.soft_limit_in_bytes file can't
be accessed.

Bug: 73483785
Test: verified logcat output
Change-Id: I03df7831f41f512ac8d3ebc46330546d08a3cbc6
This commit is contained in:
Suren Baghdasaryan 2018-03-20 16:03:29 -07:00
parent f584fff7aa
commit bb7747bec2
1 changed files with 15 additions and 1 deletions
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16
lmkd.c
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@ -18,6 +18,7 @@
#include <errno.h>
#include <inttypes.h>
#include <pwd.h>
#include <sched.h>
#include <signal.h>
#include <stdbool.h>
@ -72,6 +73,9 @@
#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
#define EIGHT_MEGA (1 << 23)
/* Defined as ProcessList.SYSTEM_ADJ in ProcessList.java */
#define SYSTEM_ADJ (-900)
/* default to old in-kernel interface if no memory pressure events */
static int use_inkernel_interface = 1;
static bool has_inkernel_module;
@ -302,6 +306,8 @@ static void cmd_procprio(LMKD_CTRL_PACKET packet) {
char val[20];
int soft_limit_mult;
struct lmk_procprio params;
bool is_system_server;
struct passwd *pwdrec;
lmkd_pack_get_procprio(packet, &params);
@ -355,7 +361,15 @@ static void cmd_procprio(LMKD_CTRL_PACKET packet) {
"/dev/memcg/apps/uid_%d/pid_%d/memory.soft_limit_in_bytes",
params.uid, params.pid);
snprintf(val, sizeof(val), "%d", soft_limit_mult * EIGHT_MEGA);
writefilestring(path, val, true);
/*
* system_server process has no memcg under /dev/memcg/apps but should be
* registered with lmkd. This is the best way so far to identify it.
*/
is_system_server = (params.oomadj == SYSTEM_ADJ &&
(pwdrec = getpwnam("system")) != NULL &&
params.uid == pwdrec->pw_uid);
writefilestring(path, val, !is_system_server);
procp = pid_lookup(params.pid);
if (!procp) {