From: Michal Hocko mhocko@kernel.org
[ Upstream commit 91241681c62a5a690c88eb2aca027f094125eaac ]
At present the construct
if (VM_WARN(...))
will compile OK with CONFIG_DEBUG_VM=y and will fail with CONFIG_DEBUG_VM=n. The reason is that VM_{WARN,BUG}* have always been special wrt. {WARN/BUG}* and never generate any code when DEBUG_VM is disabled. So we cannot really use it in conditionals.
We considered changing things so that this construct works in both cases but that might cause unwanted code generation with CONFIG_DEBUG_VM=n. It is safer and simpler to make the build fail in both cases.
[akpm@linux-foundation.org: changelog] Signed-off-by: Michal Hocko mhocko@suse.com Reviewed-by: Andrew Morton akpm@linux-foundation.org Cc: Stephen Rothwell sfr@canb.auug.org.au Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/mmdebug.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h index 451a811f48f2..deaba1cc3cfc 100644 --- a/include/linux/mmdebug.h +++ b/include/linux/mmdebug.h @@ -36,10 +36,10 @@ void dump_mm(const struct mm_struct *mm); BUG(); \ } \ } while (0) -#define VM_WARN_ON(cond) WARN_ON(cond) -#define VM_WARN_ON_ONCE(cond) WARN_ON_ONCE(cond) -#define VM_WARN_ONCE(cond, format...) WARN_ONCE(cond, format) -#define VM_WARN(cond, format...) WARN(cond, format) +#define VM_WARN_ON(cond) (void)WARN_ON(cond) +#define VM_WARN_ON_ONCE(cond) (void)WARN_ON_ONCE(cond) +#define VM_WARN_ONCE(cond, format...) (void)WARN_ONCE(cond, format) +#define VM_WARN(cond, format...) (void)WARN(cond, format) #else #define VM_BUG_ON(cond) BUILD_BUG_ON_INVALID(cond) #define VM_BUG_ON_PAGE(cond, page) VM_BUG_ON(cond)