On Wed, 2007-04-11 at 17:53 +0800, Zhao Forrest wrote:
> I got some new information:
> Before soft lockup message is out, we have:
> [EMAIL PROTECTED] home]# cat /proc/slabinfo |grep buffer_head
> buffer_head 10927942 10942560 120 32 1 : tunables 32
> 16 8 : slabdata 341955 341955 6 : globalstat 37602996 11589379
> 1174373 6 0 1 6918 12166031 1013708
> : cpustat 35254590 2350698 13610965 907286
>
> Then after buffer_head is freed, we have:
> [EMAIL PROTECTED] home]# cat /proc/slabinfo |grep buffer_head
> buffer_head 9542 36384 120 32 1 : tunables 32 16
> 8 : slabdata 1137 1137 245 : globalstat 37602996 11589379
> 1174373 6 0 1 6983 20507478
> 1708818 : cpustat 35254625 2350704 16027174 1068367
>
> Does this huge number of buffer_head cause the soft lockup?
__blkdev_put() takes the BKL and bd_mutex
invalidate_mapping_pages() tries to take the PageLock
But no other looks seem held while free_buffer_head() is called
All these locks are preemptible (CONFIG_PREEMPT_BKL?=y) and should not
hog the cpu like that, what preemption mode have you got selected?
(CONFIG_PREEMPT_VOLUNTARY?=y)
Does this fix it?
--- fs/buffer.c~ 2007-02-01 12:00:34.000000000 +0100
+++ fs/buffer.c 2007-04-11 12:35:48.000000000 +0200
@@ -3029,6 +3029,8 @@ out:
struct buffer_head *next = bh->b_this_page;
free_buffer_head(bh);
bh = next;
+
+ cond_resched();
} while (bh != buffers_to_free);
}
return ret;
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