--- /dev/null
+From 69ef9c5141e2b03522ce7ddfa134fc35e22240b8 Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Tue, 11 Aug 2020 18:31:22 -0700
+Subject: mm, oom: make the calculation of oom badness more accurate
+
+From: Yafang Shao <laoar.shao@gmail.com>
+
+[ Upstream commit 9066e5cfb73cdbcdbb49e87999482ab615e9fc76 ]
+
+Recently we found an issue on our production environment that when memcg
+oom is triggered the oom killer doesn't chose the process with largest
+resident memory but chose the first scanned process. Note that all
+processes in this memcg have the same oom_score_adj, so the oom killer
+should chose the process with largest resident memory.
+
+Bellow is part of the oom info, which is enough to analyze this issue.
+[7516987.983223] memory: usage 16777216kB, limit 16777216kB, failcnt 52843037
+[7516987.983224] memory+swap: usage 16777216kB, limit 9007199254740988kB, failcnt 0
+[7516987.983225] kmem: usage 301464kB, limit 9007199254740988kB, failcnt 0
+[...]
+[7516987.983293] [ pid ] uid tgid total_vm rss pgtables_bytes swapents oom_score_adj name
+[7516987.983510] [ 5740] 0 5740 257 1 32768 0 -998 pause
+[7516987.983574] [58804] 0 58804 4594 771 81920 0 -998 entry_point.bas
+[7516987.983577] [58908] 0 58908 7089 689 98304 0 -998 cron
+[7516987.983580] [58910] 0 58910 16235 5576 163840 0 -998 supervisord
+[7516987.983590] [59620] 0 59620 18074 1395 188416 0 -998 sshd
+[7516987.983594] [59622] 0 59622 18680 6679 188416 0 -998 python
+[7516987.983598] [59624] 0 59624 1859266 5161 548864 0 -998 odin-agent
+[7516987.983600] [59625] 0 59625 707223 9248 983040 0 -998 filebeat
+[7516987.983604] [59627] 0 59627 416433 64239 774144 0 -998 odin-log-agent
+[7516987.983607] [59631] 0 59631 180671 15012 385024 0 -998 python3
+[7516987.983612] [61396] 0 61396 791287 3189 352256 0 -998 client
+[7516987.983615] [61641] 0 61641 1844642 29089 946176 0 -998 client
+[7516987.983765] [ 9236] 0 9236 2642 467 53248 0 -998 php_scanner
+[7516987.983911] [42898] 0 42898 15543 838 167936 0 -998 su
+[7516987.983915] [42900] 1000 42900 3673 867 77824 0 -998 exec_script_vr2
+[7516987.983918] [42925] 1000 42925 36475 19033 335872 0 -998 python
+[7516987.983921] [57146] 1000 57146 3673 848 73728 0 -998 exec_script_J2p
+[7516987.983925] [57195] 1000 57195 186359 22958 491520 0 -998 python2
+[7516987.983928] [58376] 1000 58376 275764 14402 290816 0 -998 rosmaster
+[7516987.983931] [58395] 1000 58395 155166 4449 245760 0 -998 rosout
+[7516987.983935] [58406] 1000 58406 18285584 3967322 37101568 0 -998 data_sim
+[7516987.984221] oom-kill:constraint=CONSTRAINT_MEMCG,nodemask=(null),cpuset=3aa16c9482ae3a6f6b78bda68a55d32c87c99b985e0f11331cddf05af6c4d753,mems_allowed=0-1,oom_memcg=/kubepods/podf1c273d3-9b36-11ea-b3df-246e9693c184,task_memcg=/kubepods/podf1c273d3-9b36-11ea-b3df-246e9693c184/1f246a3eeea8f70bf91141eeaf1805346a666e225f823906485ea0b6c37dfc3d,task=pause,pid=5740,uid=0
+[7516987.984254] Memory cgroup out of memory: Killed process 5740 (pause) total-vm:1028kB, anon-rss:4kB, file-rss:0kB, shmem-rss:0kB
+[7516988.092344] oom_reaper: reaped process 5740 (pause), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
+
+We can find that the first scanned process 5740 (pause) was killed, but
+its rss is only one page. That is because, when we calculate the oom
+badness in oom_badness(), we always ignore the negtive point and convert
+all of these negtive points to 1. Now as oom_score_adj of all the
+processes in this targeted memcg have the same value -998, the points of
+these processes are all negtive value. As a result, the first scanned
+process will be killed.
+
+The oom_socre_adj (-998) in this memcg is set by kubelet, because it is a
+a Guaranteed pod, which has higher priority to prevent from being killed
+by system oom.
+
+To fix this issue, we should make the calculation of oom point more
+accurate. We can achieve it by convert the chosen_point from 'unsigned
+long' to 'long'.
+
+[cai@lca.pw: reported a issue in the previous version]
+[mhocko@suse.com: fixed the issue reported by Cai]
+[mhocko@suse.com: add the comment in proc_oom_score()]
+[laoar.shao@gmail.com: v3]
+ Link: http://lkml.kernel.org/r/1594396651-9931-1-git-send-email-laoar.shao@gmail.com
+
+Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
+Acked-by: Michal Hocko <mhocko@suse.com>
+Cc: David Rientjes <rientjes@google.com>
+Cc: Qian Cai <cai@lca.pw>
+Link: http://lkml.kernel.org/r/1594309987-9919-1-git-send-email-laoar.shao@gmail.com
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ fs/proc/base.c | 11 ++++++++++-
+ include/linux/oom.h | 4 ++--
+ mm/oom_kill.c | 22 ++++++++++------------
+ 3 files changed, 22 insertions(+), 15 deletions(-)
+
+diff --git a/fs/proc/base.c b/fs/proc/base.c
+index 90d2f62a9672..5a187e9b7221 100644
+--- a/fs/proc/base.c
++++ b/fs/proc/base.c
+@@ -549,8 +549,17 @@ static int proc_oom_score(struct seq_file *m, struct pid_namespace *ns,
+ {
+ unsigned long totalpages = totalram_pages() + total_swap_pages;
+ unsigned long points = 0;
++ long badness;
++
++ badness = oom_badness(task, totalpages);
++ /*
++ * Special case OOM_SCORE_ADJ_MIN for all others scale the
++ * badness value into [0, 2000] range which we have been
++ * exporting for a long time so userspace might depend on it.
++ */
++ if (badness != LONG_MIN)
++ points = (1000 + badness * 1000 / (long)totalpages) * 2 / 3;
+
+- points = oom_badness(task, totalpages) * 1000 / totalpages;
+ seq_printf(m, "%lu\n", points);
+
+ return 0;
+diff --git a/include/linux/oom.h b/include/linux/oom.h
+index b9df34326772..2db9a1432511 100644
+--- a/include/linux/oom.h
++++ b/include/linux/oom.h
+@@ -48,7 +48,7 @@ struct oom_control {
+ /* Used by oom implementation, do not set */
+ unsigned long totalpages;
+ struct task_struct *chosen;
+- unsigned long chosen_points;
++ long chosen_points;
+
+ /* Used to print the constraint info. */
+ enum oom_constraint constraint;
+@@ -108,7 +108,7 @@ static inline vm_fault_t check_stable_address_space(struct mm_struct *mm)
+
+ bool __oom_reap_task_mm(struct mm_struct *mm);
+
+-extern unsigned long oom_badness(struct task_struct *p,
++long oom_badness(struct task_struct *p,
+ unsigned long totalpages);
+
+ extern bool out_of_memory(struct oom_control *oc);
+diff --git a/mm/oom_kill.c b/mm/oom_kill.c
+index 212e71874301..f1b810ddf232 100644
+--- a/mm/oom_kill.c
++++ b/mm/oom_kill.c
+@@ -197,17 +197,17 @@ static bool is_dump_unreclaim_slabs(void)
+ * predictable as possible. The goal is to return the highest value for the
+ * task consuming the most memory to avoid subsequent oom failures.
+ */
+-unsigned long oom_badness(struct task_struct *p, unsigned long totalpages)
++long oom_badness(struct task_struct *p, unsigned long totalpages)
+ {
+ long points;
+ long adj;
+
+ if (oom_unkillable_task(p))
+- return 0;
++ return LONG_MIN;
+
+ p = find_lock_task_mm(p);
+ if (!p)
+- return 0;
++ return LONG_MIN;
+
+ /*
+ * Do not even consider tasks which are explicitly marked oom
+@@ -219,7 +219,7 @@ unsigned long oom_badness(struct task_struct *p, unsigned long totalpages)
+ test_bit(MMF_OOM_SKIP, &p->mm->flags) ||
+ in_vfork(p)) {
+ task_unlock(p);
+- return 0;
++ return LONG_MIN;
+ }
+
+ /*
+@@ -234,11 +234,7 @@ unsigned long oom_badness(struct task_struct *p, unsigned long totalpages)
+ adj *= totalpages / 1000;
+ points += adj;
+
+- /*
+- * Never return 0 for an eligible task regardless of the root bonus and
+- * oom_score_adj (oom_score_adj can't be OOM_SCORE_ADJ_MIN here).
+- */
+- return points > 0 ? points : 1;
++ return points;
+ }
+
+ static const char * const oom_constraint_text[] = {
+@@ -311,7 +307,7 @@ static enum oom_constraint constrained_alloc(struct oom_control *oc)
+ static int oom_evaluate_task(struct task_struct *task, void *arg)
+ {
+ struct oom_control *oc = arg;
+- unsigned long points;
++ long points;
+
+ if (oom_unkillable_task(task))
+ goto next;
+@@ -337,12 +333,12 @@ static int oom_evaluate_task(struct task_struct *task, void *arg)
+ * killed first if it triggers an oom, then select it.
+ */
+ if (oom_task_origin(task)) {
+- points = ULONG_MAX;
++ points = LONG_MAX;
+ goto select;
+ }
+
+ points = oom_badness(task, oc->totalpages);
+- if (!points || points < oc->chosen_points)
++ if (points == LONG_MIN || points < oc->chosen_points)
+ goto next;
+
+ select:
+@@ -366,6 +362,8 @@ static int oom_evaluate_task(struct task_struct *task, void *arg)
+ */
+ static void select_bad_process(struct oom_control *oc)
+ {
++ oc->chosen_points = LONG_MIN;
++
+ if (is_memcg_oom(oc))
+ mem_cgroup_scan_tasks(oc->memcg, oom_evaluate_task, oc);
+ else {
+--
+2.30.2
+
projects / thirdparty / kernel / stable-queue.git / commitdiff
