On 16/5/20 11:43 am, Anand Jain wrote:
On 16/5/20 1:40 am, David Sterba wrote:
On Thu, May 14, 2020 at 03:46:59AM +0800, Anand Jain wrote:
A full list of tests just started.
fs/btrfs/volumes.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 60ab41c12e50..ebc8565d0f73 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -984,7 +984,6 @@ static struct btrfs_fs_devices
*clone_fs_devices(struct btrfs_fs_devices *orig)
if (IS_ERR(fs_devices))
return fs_devices;
So now here's the device_list_mutex taken by a caller but inside
clone_fs_devices there's
fs_devices = alloc_fs_devices(orig->fsid, NULL);
just before this line and it does a GFP_KERNEL allocation.
Oh right the allocations. Its not just about the other locks
as I thought before.
There are two ways to fix.
Use GFP_NOFS
I am not yet sure if it not possible. There were some previous
work on the GFP flags. I need to review them. or,
Move the allocation outside the locks.
Looking into both of these choices.
Nack. On this patch.
In general GFP_KERNEL is preferred over GFP_NOFS. For example.
--------
6165572c btrfs: use GFP_KERNEL in btrfs_init_dev_replace_tgtdev
cc8385b5 btrfs: preallocate radix tree node for readahead
78f2c9e6 btrfs: device add and remove: use GFP_KERNEL
--------
And there are quite a lot of GFP_KERNEL allocation along the
path leading to clone_fs_devices().
Thanks, Anand
Thanks, Anand
This could
deadlock through the allocator trying to flush data and then superblock
write locking the device_list_mutex again.
- mutex_lock(&orig->device_list_mutex);
fs_devices->total_devices = orig->total_devices;
list_for_each_entry(orig_dev, &orig->devices, dev_list) {
