Re: linux-next: build failure after merge of the bpf-next tree

Alexei Starovoitov
2025-03-19T02:47:04Z

On Tue, Mar 18, 2025 at 7:33 PM Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
> Hi all,
>
> After merging the bpf-next tree, today's linux-next build (x86_64
> allmodconfig) failed like this:
>
> In file included from include/asm-generic/percpu.h:7,
> from arch/x86/include/asm/percpu.h:630,
> from arch/x86/include/asm/preempt.h:6,
> from include/linux/preempt.h:79,
> from include/linux/smp.h:116,
> from kernel/locking/qspinlock.c:16:
> kernel/locking/qspinlock.h: In function 'decode_tail':
> include/linux/percpu-defs.h:219:45: error: initialization from pointer to non-enclosed address space
> 219 | const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL; \
> | ^
> include/linux/percpu-defs.h:237:9: note: in expansion of macro '__verify_pcpu_ptr'
> 237 | __verify_pcpu_ptr(ptr); \
> | ^~~~~~~~~~~~~~~~~
> kernel/locking/qspinlock.h:67:16: note: in expansion of macro 'per_cpu_ptr'
> 67 | return per_cpu_ptr(&qnodes[idx].mcs, cpu);
> | ^~~~~~~~~~~
> include/linux/percpu-defs.h:219:45: note: expected 'const __seg_gs void *' but pointer is of type 'struct mcs_spinlock *'
> 219 | const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL; \
> | ^
> include/linux/percpu-defs.h:237:9: note: in expansion of macro '__verify_pcpu_ptr'
> 237 | __verify_pcpu_ptr(ptr); \
> | ^~~~~~~~~~~~~~~~~
> kernel/locking/qspinlock.h:67:16: note: in expansion of macro 'per_cpu_ptr'
> 67 | return per_cpu_ptr(&qnodes[idx].mcs, cpu);
> | ^~~~~~~~~~~
> kernel/locking/qspinlock.c: In function 'native_queued_spin_lock_slowpath':
> kernel/locking/qspinlock.c:285:41: error: passing argument 2 of 'decode_tail' from pointer to non-enclosed address space
> 285 | prev = decode_tail(old, qnodes);
> | ^~~~~~
> In file included from kernel/locking/qspinlock.c:30:
> kernel/locking/qspinlock.h:62:79: note: expected 'struct qnode *' but argument is of type '__seg_gs struct qnode *'
> 62 | static inline __pure struct mcs_spinlock *decode_tail(u32 tail, struct qnode *qnodes)
> | ~~~~~~~~~~~~~~^~~~~~
> In file included from kernel/locking/qspinlock.c:401:
> kernel/locking/qspinlock.c: In function '__pv_queued_spin_lock_slowpath':
> kernel/locking/qspinlock.c:285:41: error: passing argument 2 of 'decode_tail' from pointer to non-enclosed address space
> 285 | prev = decode_tail(old, qnodes);
> | ^~~~~~
> kernel/locking/qspinlock.h:62:79: note: expected 'struct qnode *' but argument is of type '__seg_gs struct qnode *'
> 62 | static inline __pure struct mcs_spinlock *decode_tail(u32 tail, struct qnode *qnodes)
> | ~~~~~~~~~~~~~~^~~~~~
>
> Caused by the resilient-queued-spin-lock branch of the bpf-next tree
> interacting with the "Enable strict percpu address space checks" series
> form the mm-stable tree.

Do you mean this set:
https://lore.kernel.org/all/20250127160709.80604-1-ubizjak@gmail.com/

>
> I don't know why this happens, but reverting that branch inf the bpf-next
> tree makes the failure go away, so I have done that for today.

Kumar,

pls take a look.