linux-next: build failure after merge of the akpm-current tree

Hi Andrew,

After merging the akpm tree, today's linux-next build (powerpc allyesconfig) failed like this:

In file included from include/linux/kernel.h:10:0,

                 from include/linux/list.h:9,
                 from include/linux/preempt.h:11,
                 from include/linux/spinlock.h:51,
                 from include/linux/seqlock.h:36,
                 from include/linux/time.h:6,
                 from fs/proc/inode.c:9:
fs/proc/inode.c: In function 'proc_init_kmemcache':
include/linux/compiler.h:339:38: error: call to '__compiletime_assert_110' declared with attribute error: BUILD_BUG_ON failed: sizeof(struct proc_dir_entry) >= SIZEOF_PDE
  _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
                                      ^
include/linux/compiler.h:319:4: note: in definition of macro '__compiletime_assert'
    prefix ## suffix();    \
    ^~~~~~

include/linux/compiler.h:339:2: note: in expansion of macro '_compiletime_assert'
_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) ^~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:45:37: note: in expansion of macro 'compiletime_assert'

 #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
                                     ^~~~~~~~~~~~~~~~~~

include/linux/build_bug.h:69:2: note: in expansion of macro 'BUILD_BUG_ON_MSG'
BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) ^~~~~~~~~~~~~~~~
fs/proc/inode.c:110:2: note: in expansion of macro 'BUILD_BUG_ON'
BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE); ^~~~~~~~~~~~

Caused by commit

527ae8759f10 ("proc: fixup PDE allocation bloat")

I have reverted that commit for today.

Cheers,
Stephen Rothwell

Can't reproduce it with commit 7aa4b0a46be8badd053c958481f0e89e634ae4df (the one before revert) both on 32-bit and 64-bit.

Can you post fs/proc/inode.i ?

Hi Alexey,

Attached (xz compresesed).

This is built with gcc 7.3.1 (built from source) hosted on PowerPC LE and targeted at PowerPC BE (a powerpc allyesconfig build). I did not have any trouble with any of my other PowerPC targeted builds.

Cheers,
Stephen Rothwell

I'm not sure what's going on. Taking preprocessed file and compiling it with ppc64 cross compiler gives sizeof(struct proc_dir_entry) = 232.

Anyway here is obvious fixlet:

[PATCH -mm] proc: fix BUILD_BUG_ON breakage on powerpc64-allyesconfig

---

 fs/proc/internal.h |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

@@ -65,12 +65,12 @@ struct proc_dir_entry {
 	char inline_name[];
 } __randomize_layout;
 
-#ifdef CONFIG_64BIT
-#define SIZEOF_PDE	(sizeof(spinlock_t) <= 4 ? 192 : 256)
-#else
-#define SIZEOF_PDE	(sizeof(spinlock_t) <= 4 ? 128 : 192)
-#endif
-
+#define SIZEOF_PDE	(				\
+	sizeof(struct proc_dir_entry) < 128 ? 128 :	\
+	sizeof(struct proc_dir_entry) < 192 ? 192 :	\
+	sizeof(struct proc_dir_entry) < 256 ? 256 :	\
+	sizeof(struct proc_dir_entry) < 512 ? 512 :	\
+	0)
 #define SIZEOF_PDE_INLINE_NAME (SIZEOF_PDE - sizeof(struct proc_dir_entry))
 
 extern struct kmem_cache *proc_dir_entry_cache;