On Sat, 2017-10-07 at 17:55 +0800, Jia-Ju Bai wrote:
> The kernel may sleep under a spinlock, and the function call paths are:
> afs_do_unlk (acquire the spinlock)
> posix_lock_file
> posix_lock_inode (fs/locks.c)
> locks_get_lock_context
> kmem_cache_alloc(GFP_KERNEL) --> may sleep
>
> afs_do_setlk (acquire the spinlock)
> posix_lock_file
> posix_lock_inode (fs/locks.c)
> locks_get_lock_context
> kmem_cache_alloc(GFP_KERNEL) --> may sleep
>
> To fix them, GFP_KERNEL is replaced with GFP_ATOMIC.
> These bugs are found by my static analysis tool and my code review.
>
> Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxx>
> ---
> fs/locks.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/locks.c b/fs/locks.c
> index 1bd71c4..975cc62 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -222,7 +222,7 @@ struct file_lock_list_struct {
> if (likely(ctx) || type == F_UNLCK)
> goto out;
>
> - ctx = kmem_cache_alloc(flctx_cache, GFP_KERNEL);
> + ctx = kmem_cache_alloc(flctx_cache, GFP_ATOMIC);
> if (!ctx)
> goto out;
>
NAK
This needs to be fixed in the AFS code. It should not be calling these
functions with a spinlock held.
--
Jeff Layton <jlayton@xxxxxxxxxx>
