On Mon, 2017-06-05 at 16:05 +0800, Jia-Ju Bai wrote: > The driver may sleep under a rcu read lock, and function call path > is: > nfs_permission (acquire the lock by rcu_read_lock) > nfs_do_access > nfs_access_add_cache > kmalloc(GFP_KERNEL) --> may sleep > > To fix it, "GFP_KERNEL" is replaced with "GFP_ATOMIC". > > Signed-off-by: Jia-Ju Bai <[email protected]> > --- > fs/nfs/dir.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c > index 32ccd77..7a074db 100644 > --- a/fs/nfs/dir.c > +++ b/fs/nfs/dir.c > @@ -2333,7 +2333,7 @@ static void nfs_access_add_rbtree(struct inode > *inode, struct nfs_access_entry * > > void nfs_access_add_cache(struct inode *inode, struct > nfs_access_entry *set) > { > - struct nfs_access_entry *cache = kmalloc(sizeof(*cache), > GFP_KERNEL); > + struct nfs_access_entry *cache = kmalloc(sizeof(*cache), > GFP_ATOMIC); > if (cache == NULL) > return; > RB_CLEAR_NODE(&cache->rb_node);
The RCU locked codepath will not ever hit nfs_access_add_rbtree(). It returns with an error code of -ECHILD after the test of "may_block". Cheers Trond -- Trond Myklebust Linux NFS client maintainer, PrimaryData [email protected]
