The patch titled
oom: move oom_adj value from task_struct to mm_struct
has been added to the -mm tree. Its filename is
oom-move-oom_adj-value-from-task_struct-to-mm_struct.patch
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------------------------------------------------------
Subject: oom: move oom_adj value from task_struct to mm_struct
From: David Rientjes <rientjes@xxxxxxxxxx>
The per-task oom_adj value is a characteristic of its mm more than the
task itself since it's not possible to oom kill any thread that shares the
mm. If a task were to be killed while attached to an mm that could not be
freed because another thread were set to OOM_DISABLE, it would have
needlessly been terminated since there is no potential for future memory
freeing.
This patch moves oomkilladj (now more appropriately named oom_adj) from
struct task_struct to struct mm_struct. This requires task_lock() on a
task to check its oom_adj value to protect against exec, but it's already
necessary to take the lock when dereferencing the mm to find the total VM
size for the badness heuristic.
This fixes a livelock if the oom killer chooses a task and another thread
sharing the same memory has an oom_adj value of OOM_DISABLE. This occurs
because oom_kill_task() repeatedly returns 1 and refuses to kill the
chosen task while select_bad_process() will repeatedly choose the same
task during the next retry.
Taking task_lock() in select_bad_process() to check for OOM_DISABLE and in
oom_kill_task() to check for threads sharing the same memory will be
removed in the next patch in this series where it will no longer be
necessary.
Writing to /proc/pid/oom_adj for a kthread will now return -EINVAL since
these threads are immune from oom killing already. They simply report an
oom_adj value of OOM_DISABLE.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxx>
Cc: San Mehat <san@xxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Peter Ziljstra <a.p.ziljstra@xxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
Cc: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/filesystems/proc.txt | 15 ++++++---
drivers/staging/android/lowmemorykiller.c | 12 +++----
fs/proc/base.c | 19 ++++++++++-
include/linux/mm_types.h | 2 +
include/linux/sched.h | 1
mm/oom_kill.c | 32 ++++++++++++--------
6 files changed, 54 insertions(+), 27 deletions(-)
diff -puN Documentation/filesystems/proc.txt~oom-move-oom_adj-value-from-task_struct-to-mm_struct Documentation/filesystems/proc.txt
--- a/Documentation/filesystems/proc.txt~oom-move-oom_adj-value-from-task_struct-to-mm_struct
+++ a/Documentation/filesystems/proc.txt
@@ -1003,11 +1003,13 @@ CHAPTER 3: PER-PROCESS PARAMETERS
3.1 /proc/<pid>/oom_adj - Adjust the oom-killer score
------------------------------------------------------
-This file can be used to adjust the score used to select which processes
-should be killed in an out-of-memory situation. Giving it a high score will
-increase the likelihood of this process being killed by the oom-killer. Valid
-values are in the range -16 to +15, plus the special value -17, which disables
-oom-killing altogether for this process.
+This file can be used to adjust the score used to select which processes should
+be killed in an out-of-memory situation. The oom_adj value is a characteristic
+of the task's mm, so all threads that share an mm with pid will have the same
+oom_adj value. A high value will increase the liklihood of this process being
+killed by the oom-killer. Valid values are in the range -16 to +15 as
+explained below and a special value of -17, which disables oom-killing
+altogether for threads sharing pid's mm.
The process to be killed in an out-of-memory situation is selected among all others
based on its badness score. This value equals the original memory size of the process
@@ -1021,6 +1023,9 @@ the parent's score if they do not share
are the prime candidates to be killed. Having only one 'hungry' child will make
parent less preferable than the child.
+/proc/<pid>/oom_adj cannot be changed for kthreads since they are immune from
+oom-killing already.
+
/proc/<pid>/oom_score shows process' current badness score.
The following heuristics are then applied:
diff -puN drivers/staging/android/lowmemorykiller.c~oom-move-oom_adj-value-from-task_struct-to-mm_struct drivers/staging/android/lowmemorykiller.c
--- a/drivers/staging/android/lowmemorykiller.c~oom-move-oom_adj-value-from-task_struct-to-mm_struct
+++ a/drivers/staging/android/lowmemorykiller.c
@@ -73,17 +73,17 @@ static int lowmem_shrink(int nr_to_scan,
lowmem_print(3, "lowmem_shrink %d, %x, ofree %d, ma %d\n", nr_to_scan, gfp_mask, other_free, min_adj);
read_lock(&tasklist_lock);
for_each_process(p) {
- if(p->oomkilladj >= 0 && p->mm) {
+ if(p->mm->oom_adj >= 0 && p->mm) {
tasksize = get_mm_rss(p->mm);
- if(nr_to_scan > 0 && tasksize > 0 && p->oomkilladj >= min_adj) {
+ if(nr_to_scan > 0 && tasksize > 0 && p->mm->oom_adj >= min_adj) {
if(selected == NULL ||
- p->oomkilladj > selected->oomkilladj ||
- (p->oomkilladj == selected->oomkilladj &&
+ p->mm->oom_adj > selected->mm->oom_adj ||
+ (p->mm->oom_adj == selected->mm->oom_adj &&
tasksize > selected_tasksize)) {
selected = p;
selected_tasksize = tasksize;
lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
- p->pid, p->comm, p->oomkilladj, tasksize);
+ p->pid, p->comm, p->mm->oom_adj, tasksize);
}
}
rem += tasksize;
@@ -92,7 +92,7 @@ static int lowmem_shrink(int nr_to_scan,
if(selected != NULL) {
lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
selected->pid, selected->comm,
- selected->oomkilladj, selected_tasksize);
+ selected->mm->oom_adj, selected_tasksize);
force_sig(SIGKILL, selected);
rem -= selected_tasksize;
}
diff -puN fs/proc/base.c~oom-move-oom_adj-value-from-task_struct-to-mm_struct fs/proc/base.c
--- a/fs/proc/base.c~oom-move-oom_adj-value-from-task_struct-to-mm_struct
+++ a/fs/proc/base.c
@@ -1006,7 +1006,12 @@ static ssize_t oom_adjust_read(struct fi
if (!task)
return -ESRCH;
- oom_adjust = task->oomkilladj;
+ task_lock(task);
+ if (task->mm)
+ oom_adjust = task->mm->oom_adj;
+ else
+ oom_adjust = OOM_DISABLE;
+ task_unlock(task);
put_task_struct(task);
len = snprintf(buffer, sizeof(buffer), "%i\n", oom_adjust);
@@ -1035,11 +1040,19 @@ static ssize_t oom_adjust_write(struct f
task = get_proc_task(file->f_path.dentry->d_inode);
if (!task)
return -ESRCH;
- if (oom_adjust < task->oomkilladj && !capable(CAP_SYS_RESOURCE)) {
+ task_lock(task);
+ if (!task->mm) {
+ task_unlock(task);
+ put_task_struct(task);
+ return -EINVAL;
+ }
+ if (oom_adjust < task->mm->oom_adj && !capable(CAP_SYS_RESOURCE)) {
+ task_unlock(task);
put_task_struct(task);
return -EACCES;
}
- task->oomkilladj = oom_adjust;
+ task->mm->oom_adj = oom_adjust;
+ task_unlock(task);
put_task_struct(task);
if (end - buffer == 0)
return -EIO;
diff -puN include/linux/mm_types.h~oom-move-oom_adj-value-from-task_struct-to-mm_struct include/linux/mm_types.h
--- a/include/linux/mm_types.h~oom-move-oom_adj-value-from-task_struct-to-mm_struct
+++ a/include/linux/mm_types.h
@@ -232,6 +232,8 @@ struct mm_struct {
unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */
+ s8 oom_adj; /* OOM kill score adjustment (bit shift) */
+
cpumask_t cpu_vm_mask;
/* Architecture-specific MM context */
diff -puN include/linux/sched.h~oom-move-oom_adj-value-from-task_struct-to-mm_struct include/linux/sched.h
--- a/include/linux/sched.h~oom-move-oom_adj-value-from-task_struct-to-mm_struct
+++ a/include/linux/sched.h
@@ -1150,7 +1150,6 @@ struct task_struct {
* a short time
*/
unsigned char fpu_counter;
- s8 oomkilladj; /* OOM kill score adjustment (bit shift). */
#ifdef CONFIG_BLK_DEV_IO_TRACE
unsigned int btrace_seq;
#endif
diff -puN mm/oom_kill.c~oom-move-oom_adj-value-from-task_struct-to-mm_struct mm/oom_kill.c
--- a/mm/oom_kill.c~oom-move-oom_adj-value-from-task_struct-to-mm_struct
+++ a/mm/oom_kill.c
@@ -58,6 +58,7 @@ unsigned long badness(struct task_struct
unsigned long points, cpu_time, run_time;
struct mm_struct *mm;
struct task_struct *child;
+ int oom_adj;
task_lock(p);
mm = p->mm;
@@ -65,6 +66,7 @@ unsigned long badness(struct task_struct
task_unlock(p);
return 0;
}
+ oom_adj = mm->oom_adj;
/*
* The memory size of the process is the basis for the badness.
@@ -148,15 +150,15 @@ unsigned long badness(struct task_struct
points /= 8;
/*
- * Adjust the score by oomkilladj.
+ * Adjust the score by oom_adj.
*/
- if (p->oomkilladj) {
- if (p->oomkilladj > 0) {
+ if (oom_adj) {
+ if (oom_adj > 0) {
if (!points)
points = 1;
- points <<= p->oomkilladj;
+ points <<= oom_adj;
} else
- points >>= -(p->oomkilladj);
+ points >>= -(oom_adj);
}
#ifdef DEBUG
@@ -251,8 +253,10 @@ static struct task_struct *select_bad_pr
*ppoints = ULONG_MAX;
}
- if (p->oomkilladj == OOM_DISABLE)
+ task_lock(p);
+ if (p->mm && p->mm->oom_adj == OOM_DISABLE)
continue;
+ task_unlock(p);
points = badness(p, uptime.tv_sec);
if (points > *ppoints || !chosen) {
@@ -304,8 +308,7 @@ static void dump_tasks(const struct mem_
}
printk(KERN_INFO "[%5d] %5d %5d %8lu %8lu %3d %3d %s\n",
p->pid, __task_cred(p)->uid, p->tgid, mm->total_vm,
- get_mm_rss(mm), (int)task_cpu(p), p->oomkilladj,
- p->comm);
+ get_mm_rss(mm), (int)task_cpu(p), mm->oom_adj, p->comm);
task_unlock(p);
} while_each_thread(g, p);
}
@@ -367,8 +370,12 @@ static int oom_kill_task(struct task_str
* Don't kill the process if any threads are set to OOM_DISABLE
*/
do_each_thread(g, q) {
- if (q->mm == mm && q->oomkilladj == OOM_DISABLE)
+ task_lock(q);
+ if (q->mm == mm && q->mm && q->mm->oom_adj == OOM_DISABLE) {
+ task_unlock(q);
return 1;
+ }
+ task_unlock(q);
} while_each_thread(g, q);
__oom_kill_task(p, 1);
@@ -393,10 +400,11 @@ static int oom_kill_process(struct task_
struct task_struct *c;
if (printk_ratelimit()) {
- printk(KERN_WARNING "%s invoked oom-killer: "
- "gfp_mask=0x%x, order=%d, oomkilladj=%d\n",
- current->comm, gfp_mask, order, current->oomkilladj);
task_lock(current);
+ printk(KERN_WARNING "%s invoked oom-killer: "
+ "gfp_mask=0x%x, order=%d, oom_adj=%d\n",
+ current->comm, gfp_mask, order,
+ current->mm ? current->mm->oom_adj : OOM_DISABLE);
cpuset_print_task_mems_allowed(current);
task_unlock(current);
dump_stack();
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
linux-next.patch
cpusets-restructure-the-function-cpuset_update_task_memory_state.patch
cpusets-update-tasks-page-slab-spread-flags-in-time.patch
cpusetmm-update-tasks-mems_allowed-in-time.patch
cpusetmm-update-tasks-mems_allowed-in-time-fix.patch
cpusetmm-update-tasks-mems_allowed-in-time-cleanup.patch
page-allocator-use-a-pre-calculated-value-instead-of-num_online_nodes-in-fast-paths-do-not-override-definition-of-node_set_online-with-macro.patch
mm-setup_per_zone_inactive_ratio-do-not-call-for-int_sqrt-if-not-needed.patch
mm-setup_per_zone_inactive_ratio-fix-comment-and-make-it-__init.patch
mm-invoke-oom-killer-for-__gfp_nofail.patch
oom-fix-possible-oom_dump_tasks-null-pointer.patch
oom-move-oom_adj-value-from-task_struct-to-mm_struct.patch
memcg-add-file-based-rss-accounting.patch
memcg-add-file-based-rss-accounting-fix-mem_cgroup_update_mapped_file_stat-oops.patch
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