Hi,
> +CC btrfs
>
> On 4/1/21 12:51 PM, Wang Yugui wrote:
> > Hi,
> >
> > an unexpected -ENOMEM from percpu_counter_init() happened when xfstest
> > with kernel 5.11.10 and 5.10.27
>
> Is there a dmesg log showing allocation failure or something?
When unexpected -ENOMEM of percpu_counter_init(), btrfs as upper caller
finally output something to dmesg.
And we add one trace to btrfs source to make sure that.
> if (ret == -ENOMEM) printk("ENOMEM btrfs_drew_lock_init\n");
Now the reproduce frequency become from >50% to not happen or very slow
with the flowing change.
diff --git a/mm/percpu.c b/mm/percpu.c
index 6596a0a..0127be1 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -104,8 +104,8 @@
/* chunks in slots below this are subject to being sidelined on failed alloc */
#define PCPU_SLOT_FAIL_THRESHOLD 3
-#define PCPU_EMPTY_POP_PAGES_LOW 2
-#define PCPU_EMPTY_POP_PAGES_HIGH 4
+#define PCPU_EMPTY_POP_PAGES_LOW 8
+#define PCPU_EMPTY_POP_PAGES_HIGH 16
#ifdef CONFIG_SMP
/* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 5e76af7..8cc091b 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -14,7 +14,7 @@
/* enough to cover all DEFINE_PER_CPUs in modules */
#ifdef CONFIG_MODULES
-#define PERCPU_MODULE_RESERVE (8 << 10)
+#define PERCPU_MODULE_RESERVE (32 << 10)
#else
#define PERCPU_MODULE_RESERVE 0
#endif
Just some guess,
1) maybe some releationship to the trigger of 'vm.dirty_bytes=10737418240'.
this problem happen in
server/T7610 with E5-2660v2 *2 and SSD/SAS(6Gb/s) and 192G memory
but not happen in
server/T620 with E5-2680v2 *2 and SSD/NVMe and 192G memory.
2) maybe some releationship to numa.
128G memory in node1(CPU1), and 64G in node2(CPU2)
Best Regards
Wang Yugui (wangyugui@xxxxxxxxxxxx)
2021/04/07
> > direct caller:
> > int btrfs_drew_lock_init(struct btrfs_drew_lock *lock)
> > {
> > int ret;
> >
> > ret = percpu_counter_init(&lock->writers, 0, GFP_KERNEL);
> > if (ret)
> > return ret;
> >
> > atomic_set(&lock->readers, 0);
> > init_waitqueue_head(&lock->pending_readers);
> > init_waitqueue_head(&lock->pending_writers);
> >
> > return 0;
> > }
> >
> > upper caller:
> > nofs_flag = memalloc_nofs_save();
> > ret = btrfs_drew_lock_init(&root->snapshot_lock);
> > memalloc_nofs_restore(nofs_flag);
> > if (ret == -ENOMEM) printk("ENOMEM btrfs_drew_lock_init\n");
> > if (ret)
> > goto fail;
> >
> > The hardware of this server:
> > CPU: Xeon(R) CPU E5-2660 v2(10 core) *2
> > memory: 192G, no swap
> >
> > Only one xfstests job is running in this server, and about 7% of memory
> > is used.
> >
> > Any advice please.
> >
> > Best Regards
> > Wang Yugui (wangyugui@xxxxxxxxxxxx)
> > 2021/04/01
> >
> >
