Messages in this thread Patch in this message | | | Date | Tue, 6 Mar 2012 23:26:08 -0800 | From | Fengguang Wu <> | Subject | Re: inode->i_wb_list corruption. |
| |
On Tue, Mar 06, 2012 at 10:03:07PM +0100, Jan Kara wrote: > On Tue 06-03-12 13:51:37, Dave Jones wrote: > > We've had three separate reports against 3.2.x recently where the linked list debugging > > is getting tripped up by the prev->next pointer being null instead of pointing > > to the current list entry while walking the i_wb_list > > > > Call traces are slightly different each time, but all end up walking i_wb_list > > in dput -> d_kill -> i_put -> evict -> inode_wb_list_del > > > > What protects that list ? It looks to be just bdi->wb.list_lock ? > > > > > > full reports at: > > https://bugzilla.redhat.com/show_bug.cgi?id=784741 > > https://bugzilla.redhat.com/show_bug.cgi?id=799229 > > https://bugzilla.redhat.com/show_bug.cgi?id=799692 > Hum, interesting! I'd guess this might be caused by f758eeab - adding > Fengguang and Christoph to CC. But I'm really failing to see how this could > happen but interesting thing is that in two of the three cases the files > are on virtual filesystems (once cgroup, once sysfs). These both use > noop_backing_dev_info.
sysfs/cgroup forgot to init inode->i_wb_list?
This simplified fix inits it in inode_init_always().
The better fix would be to add init_once to sysfs or perhaps fix sysfs_get_inode()/cgroup_new_inode().
Thanks, Fengguang
--- fs/inode.c | 1 + 1 file changed, 1 insertion(+)
--- linux.orig/fs/inode.c 2012-02-22 19:20:48.374799955 -0800 +++ linux/fs/inode.c 2012-03-06 23:11:29.133899478 -0800 @@ -193,6 +193,7 @@ int inode_init_always(struct super_block inode->i_private = NULL; inode->i_mapping = mapping; INIT_LIST_HEAD(&inode->i_dentry); /* buggered by rcu freeing */ + INIT_LIST_HEAD(&inode->i_wb_list); #ifdef CONFIG_FS_POSIX_ACL inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED; #endif
| |