On Wed, 19 Mar 2025 at 14:37, Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx> wrote: > > On Wed, 19 Mar 2025 at 03:47, Alexei Starovoitov > <alexei.starovoitov@xxxxxxxxx> wrote: > > > > On Tue, Mar 18, 2025 at 7:33 PM Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> 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@xxxxxxxxx/ > > > > > > > > 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. > > I've sent a fix [0], but unfortunately I was unable to reproduce the > problem with an LLVM >= 19 build, idk why. I will try with GCC >= 14 > as the patches require to confirm, but based on the error I am 99% > sure it will fix the problem. Probably because __seg_gs has CC_HAS_NAMED_AS depends on CC_IS_GCC. Let me give it a go with GCC. > > [0] https://lore.kernel.org/bpf/20250319133523.641009-1-memxor@xxxxxxxxx > > Feel free to cherry-pick or squash into the fixed commit, whatever is best.
