On Wed, Dec 13, 2023, at 11:05, kernel test robot wrote: > commit: 4a0d72ea10ce156eb2 [7115/7300] afs: Overhaul invalidation handling to better support RO volumes > config: arm-randconfig-003-20231213 > (https://download.01.org/0day-ci/archive/20231213/202312131823.hO2NP34f-lkp@xxxxxxxxx/config) > All errors (new ones prefixed by >>): > >>> ld.lld: error: undefined symbol: __bad_xchg > >>> referenced by callback.c > >>> fs/afs/callback.o:(__afs_break_callback) in > archive vmlinux.a > >>> referenced by rotate.c > >>> fs/afs/rotate.o:(afs_select_fileserver) in archive > vmlinux.a I saw the same thing, and this seems to be broken on all 32-bit architectures: @@ -79,9 +79,9 @@ void __afs_break_callback(struct afs_vnode *vnode, enum afs_cb_break_reason reas _enter(""); clear_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags); - if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) { + if (xchg(&vnode->cb_expires_at, AFS_NO_CB_PROMISE) != AFS_NO_CB_PROMISE) { vnode->cb_break++; I tried to replace this with xchg64(), but that only exists on one architectures (unlike cmpxchg64(), which is on most but not all 32-bit ones). If this has to be an atomic operation, the only portable way I see is to change cb_expires_at into an atomic64_t and modify all references to use atomic operations. Arnd
