This patch is just a preparatory and it doesn't introduce any functional
change.
Note:
I am utterly unhappy about lowmemory killer abusing TIF_MEMDIE just to
wait for the oom victim and to prevent from new killing. This is
just a side effect of the flag. The primary meaning is to give the oom
victim access to the memory reserves and that shouldn't be necessary
here.
Signed-off-by: Michal Hocko <mho...@suse.cz>
---
drivers/staging/android/lowmemorykiller.c | 7 ++++++-
include/linux/oom.h | 4 ++++
kernel/exit.c | 2 +-
mm/memcontrol.c | 2 +-
mm/oom_kill.c | 23 ++++++++++++++++++++---
5 files changed, 32 insertions(+), 6 deletions(-)
diff --git a/drivers/staging/android/lowmemorykiller.c
b/drivers/staging/android/lowmemorykiller.c
index b545d3d1da3e..feafa172b155 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -160,7 +160,12 @@ static unsigned long lowmem_scan(struct shrinker *s,
struct shrink_control *sc)
selected->pid, selected->comm,
selected_oom_score_adj, selected_tasksize);
lowmem_deathpending_timeout = jiffies + HZ;
- set_tsk_thread_flag(selected, TIF_MEMDIE);
+ /*
+ * FIXME: lowmemorykiller shouldn't abuse global OOM killer
+ * infrastructure. There is no real reason why the selected
+ * task should have access to the memory reserves.
+ */
+ mark_tsk_oom_victim(selected);
send_sig(SIGKILL, selected, 0);
rem += selected_tasksize;
}
diff --git a/include/linux/oom.h b/include/linux/oom.h
index 76200984d1e2..b42b80f88c3a 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -47,6 +47,10 @@ static inline bool oom_task_origin(const struct task_struct
*p)
return !!(p->signal->oom_flags & OOM_FLAG_ORIGIN);
}
+extern void mark_tsk_oom_victim(struct task_struct *tsk);
+
+extern void unmark_oom_victim(void);
+
extern unsigned long oom_badness(struct task_struct *p,
struct mem_cgroup *memcg, const nodemask_t *nodemask,
unsigned long totalpages);
diff --git a/kernel/exit.c b/kernel/exit.c
index 287884b05b89..5db52e52c493 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -456,7 +456,7 @@ static void exit_mm(struct task_struct *tsk)
task_unlock(tsk);
mm_update_next_owner(mm);
mmput(mm);
- clear_thread_flag(TIF_MEMDIE);
+ unmark_oom_victim();
}
static struct task_struct *find_alive_thread(struct task_struct *p)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0021313d1210..18ecef729597 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1559,7 +1559,7 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup
*memcg, gfp_t gfp_mask,
* quickly exit and free its memory.
*/
if (fatal_signal_pending(current) || task_will_free_mem(current)) {
- set_thread_flag(TIF_MEMDIE);
+ mark_tsk_oom_victim(current);
return;
}
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 294493a7ae4b..80b34e285f96 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -416,6 +416,23 @@ void note_oom_kill(void)
atomic_inc(&oom_kills);
}
+/**
+ * mark_tsk_oom_victim - marks the given taks as OOM victim.
+ * @tsk: task to mark
+ */
+void mark_tsk_oom_victim(struct task_struct *tsk)
+{
+ set_tsk_thread_flag(tsk, TIF_MEMDIE);
+}
+
+/**
+ * unmark_oom_victim - unmarks the current task as OOM victim.
+ */
+void unmark_oom_victim(void)
+{
+ clear_thread_flag(TIF_MEMDIE);
+}
+
#define K(x) ((x) << (PAGE_SHIFT-10))
/*
* Must be called while holding a reference to p, which will be released upon
@@ -440,7 +457,7 @@ void oom_kill_process(struct task_struct *p, gfp_t
gfp_mask, int order,
*/
task_lock(p);
if (p->mm && task_will_free_mem(p)) {
- set_tsk_thread_flag(p, TIF_MEMDIE);
+ mark_tsk_oom_victim(p);
task_unlock(p);
put_task_struct(p);
return;
@@ -495,7 +512,7 @@ void oom_kill_process(struct task_struct *p, gfp_t
gfp_mask, int order,
/* mm cannot safely be dereferenced after task_unlock(victim) */
mm = victim->mm;
- set_tsk_thread_flag(victim, TIF_MEMDIE);
+ mark_tsk_oom_victim(victim);
pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB,
file-rss:%lukB\n",
task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
K(get_mm_counter(victim->mm, MM_ANONPAGES)),
@@ -652,7 +669,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t
gfp_mask,
*/
if (current->mm &&
(fatal_signal_pending(current) || task_will_free_mem(current))) {
- set_thread_flag(TIF_MEMDIE);
+ mark_tsk_oom_victim(current);
return;
}
--
2.1.4
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