Re: [RFC v3 12/13] vfs: add debugfs support
From: David Sterba
Date: Wed Oct 10 2012 - 12:53:29 EST
On Wed, Oct 10, 2012 at 06:07:34PM +0800, zwu.kernel@xxxxxxxxx wrote:
> +static int hot_debugfs_log_init(struct debugfs_vol_data *data)
> +{
> + int err = 0;
> + struct lstring *debugfs_log = data->debugfs_log;
> +
> + spin_lock(&data->log_lock);
> + debugfs_log->str = vmalloc(INIT_LOG_ALLOC_SIZE);
vmalloc __might_sleep(), do the allocation outside of the lock and assign
the value inside. Also, you may use vzalloc and drop the following memset.
dmesg:
vfs: turning on hot data tracking
BUG: sleeping function called from invalid context at mm/slab.c:3220
in_atomic(): 1, irqs_disabled(): 0, pid: 3103, name: mc
1 lock held by mc/3103:
#0: (&(&inode_data->log_lock)->rlock){+.+.+.}, at: [<ffffffff8118c656>] __hot_debugfs_comm_read+0x216/0x280
Pid: 3103, comm: mc Tainted: G W 3.6.0hottrack-default+ #208
Call Trace:
[<ffffffff8108068c>] __might_sleep+0xfc/0x130
[<ffffffff8114f7c1>] kmem_cache_alloc_trace+0xe1/0x270
[<ffffffff81142005>] __get_vm_area_node+0x95/0x1a0
[<ffffffff8108630f>] ? local_clock+0x6f/0x80
[<ffffffff8118c660>] ? __hot_debugfs_comm_read+0x220/0x280
[<ffffffff8114283d>] __vmalloc_node_range+0x6d/0x200
[<ffffffff8118c660>] ? __hot_debugfs_comm_read+0x220/0x280
[<ffffffff8118b810>] ? hot_debugfs_log+0xe0/0xe0
[<ffffffff81142a05>] __vmalloc_node+0x35/0x40
[<ffffffff8118c660>] ? __hot_debugfs_comm_read+0x220/0x280
[<ffffffff81142bcc>] vmalloc+0x2c/0x30
[<ffffffff8118c660>] __hot_debugfs_comm_read+0x220/0x280
[<ffffffff8191fd58>] ? __do_page_fault+0x238/0x590
[<ffffffff810ab825>] ? trace_hardirqs_on_caller+0x155/0x1d0
[<ffffffff8138d01e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[<ffffffff8118c6d5>] __hot_debugfs_inode_read+0x15/0x20
[<ffffffff8115a19b>] vfs_read+0xcb/0x190
[<ffffffff8115a2c2>] sys_read+0x62/0xb0
[<ffffffff8138d01e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[<ffffffff81924979>] system_call_fastpath+0x16/0x1b
> + if (debugfs_log->str) {
> + memset(debugfs_log->str, 0, INIT_LOG_ALLOC_SIZE);
> + data->log_alloc_size = INIT_LOG_ALLOC_SIZE;
> + } else {
> + err = -ENOMEM;
> + }
> + spin_unlock(&data->log_lock);
> +
> + return err;
> +}
I'm now playing with it, and haven't gone through the code yet,
david
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