On Wed, 14 Mar 2018 10:47:00 +0100 Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> On Thu 08-03-18 17:05:24, Andrew Morton wrote:
> > @@ -4374,11 +4375,8 @@ int hugetlb_reserve_pages(struct inode *
> > struct resv_map *resv_map;
> > long gbl_reserve;
> >
> > - /* This should never happen */
> > - if (from > to) {
> > - VM_WARN(1, "%s called with a negative range\n", __func__);
> > + if (VM_WARN(from > to, "%s called with a negative range\n", __func__))
> > return -EINVAL;
> > - }
> >
> > /*
> > * Only apply hugepage reservation if asked. At fault time, an
>
> My compiler chokes on this with
> In file included from ./include/linux/kernel.h:15:0,
> from ./include/linux/list.h:9,
> from mm/hugetlb.c:5:
> mm/hugetlb.c: In function 'hugetlb_reserve_pages':
> ./include/linux/build_bug.h:36:33: error: void value not ignored as it ought to be
> #define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))
> ^
> ./include/linux/mmdebug.h:52:34: note: in expansion of macro 'BUILD_BUG_ON_INVALID'
> #define VM_WARN(cond, format...) BUILD_BUG_ON_INVALID(cond)
> ^
> mm/hugetlb.c:4379:6: note: in expansion of macro 'VM_WARN'
> if (VM_WARN(from > to, "%s called with a negative range\n", __func__))
>
> I haven't explored it further yet.
Yes, sfr hit that as well. Seems that nobody has tried to use the
return value from VM_WARN[_foo]() with CONFIG_DEBUG_VM=n.
This seems to work - I'll poke at it a bit more.
--- a/include/linux/mmdebug.h~a
+++ a/include/linux/mmdebug.h
@@ -46,10 +46,10 @@ void dump_mm(const struct mm_struct *mm)
#define VM_BUG_ON_PAGE(cond, page) VM_BUG_ON(cond)
#define VM_BUG_ON_VMA(cond, vma) VM_BUG_ON(cond)
#define VM_BUG_ON_MM(cond, mm) VM_BUG_ON(cond)
-#define VM_WARN_ON(cond) BUILD_BUG_ON_INVALID(cond)
-#define VM_WARN_ON_ONCE(cond) BUILD_BUG_ON_INVALID(cond)
-#define VM_WARN_ONCE(cond, format...) BUILD_BUG_ON_INVALID(cond)
-#define VM_WARN(cond, format...) BUILD_BUG_ON_INVALID(cond)
+#define VM_WARN_ON(cond) ({ BUILD_BUG_ON_INVALID(cond); 0; })
+#define VM_WARN_ON_ONCE(cond) ({ BUILD_BUG_ON_INVALID(cond); 0; })
+#define VM_WARN_ONCE(cond, format...) ({ BUILD_BUG_ON_INVALID(cond); 0; })
+#define VM_WARN(cond, format...) ({ BUILD_BUG_ON_INVALID(cond); 0; })
#endif
#ifdef CONFIG_DEBUG_VIRTUAL
_
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