VM_BUG_ONs in PF_NO_TAIL() and PF_NO_COMPOUND() add 4+ KiB to
mm/build-in.o for DEBUG_VM kernel.
Let's hide them under new config option -- CONFIG_DEBUG_VM_PGFLAGS.
With the option enabled VM_BUG_ON_PGFLAGS() is equal to VM_BUG_ON_PAGE.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
include/linux/mmdebug.h | 6 ++++++
include/linux/page-flags.h | 8 +++-----
lib/Kconfig.debug | 8 ++++++++
3 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
index 877ef226f90f..c447d8055e50 100644
--- a/include/linux/mmdebug.h
+++ b/include/linux/mmdebug.h
@@ -55,4 +55,10 @@ void dump_mm(const struct mm_struct *mm);
#define VIRTUAL_BUG_ON(cond) do { } while (0)
#endif
+#ifdef CONFIG_DEBUG_VM_PGFLAGS
+#define VM_BUG_ON_PGFLAGS(cond, page) VM_BUG_ON_PAGE(cond, page)
+#else
+#define VM_BUG_ON_PGFLAGS(cond, page) BUILD_BUG_ON_INVALID(cond)
+#endif
+
#endif
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 19e4129f00e5..8d6e4e9a98af 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -153,12 +153,10 @@ enum pageflags {
#define PF_ANY(page, enforce) page
#define PF_HEAD(page, enforce) compound_head(page)
#define PF_NO_TAIL(page, enforce) ({ \
- if (enforce) \
- VM_BUG_ON_PAGE(PageTail(page), page); \
+ VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
compound_head(page);})
-#define PF_NO_COMPOUND(page, enforce) ({ \
- if (enforce) \
- VM_BUG_ON_PAGE(PageCompound(page), page); \
+#define PF_NO_COMPOUND(page, enforce) ({ \
+ VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
page;})
/*
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index e2894b23efb6..0d12bfa429de 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -570,6 +570,14 @@ config DEBUG_VM_RB
If unsure, say N.
+config DEBUG_VM_PGFLAGS
+ bool "Debug page-flags operations"
+ depends on DEBUG_VM
+ help
+ Enables extra validation on page flags operations.
+
+ If unsure, say N.
+
config DEBUG_VIRTUAL
bool "Debug VM translations"
depends on DEBUG_KERNEL && X86
--
2.5.1
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