Re: [hnaz-linux-mm:master 90/340] arch/x86/mm/fault.c:1468:34: sparse: sparse: incorrect type in argument 1 (different base types)

[Peter Xu <peterx@redhat.com>]

On Wed, Mar 11, 2020 at 12:30:41PM +0800, kbuild test robot wrote:
> tree:   https://github.com/hnaz/linux-mm master
> head:   5d9ee416b5701096536c7a63c04dbe25012baa9e
> commit: 79181dfcc4b8c2091126a8b3175957a598ae61e1 [90/340] x86/mm: use helper fault_signal_pending()
> reproduce:
>         # apt-get install sparse
>         # sparse version: v0.6.1-174-g094d5a94-dirty
>         git checkout 79181dfcc4b8c2091126a8b3175957a598ae61e1
>         make ARCH=x86_64 allmodconfig
>         make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'
> 
> If you fix the issue, kindly add following tag
> Reported-by: kbuild test robot <lkp@intel.com>
> 
> 
> sparse warnings: (new ones prefixed by >>)
> 
> >> arch/x86/mm/fault.c:1468:34: sparse: sparse: incorrect type in argument 1 (different base types) @@    expected unsigned int fault_flags @@    got restricted vm_fault_t [assignedunsigned int fault_flags @@
> >> arch/x86/mm/fault.c:1468:34: sparse:    expected unsigned int fault_flags
> >> arch/x86/mm/fault.c:1468:34: sparse:    got restricted vm_fault_t [assigned] [usertype] fault
> >> include/linux/sched/signal.h:381:16: sparse: sparse: restricted vm_fault_t degrades to integer

Hi, Andrew,

I'm not sure whether this comes from the extra "-fdiagnostic-prefix"
because I didn't encounter that, but if after the previous signal.h
fixup squashed into patch "mm: Introduce fault_signal_pending()", then
we have linux/mm_types.h included already, and it'll be pretty safe to
just use vm_fault_t here.

To be explicit, maybe another squash-in would work to the same patch:

-------------8<-------------
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index c8e0e4f801e4..65ea429daaa2 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -377,7 +377,7 @@ static inline int signal_pending_state(long state, struct task_struct *p)
  * instead, especially with the case where we've got interrupted with
  * a VM_FAULT_RETRY.
  */
-static inline bool fault_signal_pending(unsigned int fault_flags,
+static inline bool fault_signal_pending(vm_fault_t fault_flags,
                                        struct pt_regs *regs)
 {
        return unlikely((fault_flags & VM_FAULT_RETRY) &&
------------->8-------------

So the whole fixup is (against "mm: Introduce fault_signal_pending()"):

-------------8<-------------
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index fd64b135fd7b..4a0eafe3d932 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -154,7 +154,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
         */
        fault = handle_mm_fault(vma, address, flags);

-       if (fault_signal_pending(regs))
+       if (fault_signal_pending(fault, regs))
                return;

        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 09d40ce6a162..65ea429daaa2 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -10,6 +10,8 @@
 #include <linux/cred.h>
 #include <linux/refcount.h>
 #include <linux/posix-timers.h>
+#include <linux/mm_types.h>
+#include <asm/ptrace.h>

 /*
  * Types defining task->signal and task->sighand and APIs using them:
@@ -375,7 +377,7 @@ static inline int signal_pending_state(long state, struct task_struct *p)
  * instead, especially with the case where we've got interrupted with
  * a VM_FAULT_RETRY.
  */
-static inline bool fault_signal_pending(unsigned int fault_flags,
+static inline bool fault_signal_pending(vm_fault_t fault_flags,
                                        struct pt_regs *regs)
 {
        return unlikely((fault_flags & VM_FAULT_RETRY) &&
------------->8-------------

Thanks,

-- 
Peter Xu