with-alien leads to GC invariant lost

[Ken Olum]

After these definitions:

(define-alien-type statfs
  (struct statfs
   (type long)
   (bsize long) ;Block size
   (blocks long) ;Total blocks
   (bfree long) ;Total free blocks
   (bavail long) ;Free blocks to non-superuser
   (files long) ;Total inodes
   (ffree long) ;Free inodes
   (fsid long)
   (namelen long) ;Max filename length
   ))

(define-alien-routine statfs int
  (path c-string)
  (data (* statfs)))

This code, which worked in 1.0.56, now crashes lisp in 1 .2.5 with the error
GC invariant lost, file "gencgc.c", line 303:

(with-alien ((data statfs))
  (statfs "/" (addr data)))

Doing it without stack-allocating the structure still works:

(let ((data (make-alien statfs)))
  (statfs "/" data))

 uname -a
Linux tunic6.uit.tufts.edu 2.6.32-358.14.1.el6.x86_64 #1 SMP Mon Jun 17 15:54:20 EDT 2013 x86_64 x86_64 x86_64 GNU/Linux

 *features*

(:ALIEN-CALLBACKS :ANSI-CL :ASH-RIGHT-VOPS :C-STACK-IS-CONTROL-STACK
 :COMMON-LISP :COMPARE-AND-SWAP-VOPS :COMPLEX-FLOAT-VOPS :CYCLE-COUNTER :ELF
 :FLOAT-EQL-VOPS :GENCGC :IEEE-FLOATING-POINT :INLINE-CONSTANTS :LARGEFILE
 :LINKAGE-TABLE :LINUX :LITTLE-ENDIAN :MEMORY-BARRIER-VOPS :MULTIPLY-HIGH-VOPS
 :OS-PROVIDES-BLKSIZE-T :OS-PROVIDES-DLADDR :OS-PROVIDES-DLOPEN
 :OS-PROVIDES-GETPROTOBY-R :OS-PROVIDES-POLL :OS-PROVIDES-PUTWC
 :OS-PROVIDES-SUSECONDS-T :PACKAGE-LOCAL-NICKNAMES :RAW-INSTANCE-INIT-VOPS
 :SB-DOC :SB-EVAL :SB-FUTEX :SB-LDB :SB-PACKAGE-LOCKS :SB-SIMD-PACK
 :SB-SOURCE-LOCATIONS :SB-TEST :SB-THREAD :SB-UNICODE :SBCL
 :STACK-ALLOCATABLE-CLOSURES :STACK-ALLOCATABLE-FIXED-OBJECTS
 :STACK-ALLOCATABLE-LISTS :STACK-ALLOCATABLE-VECTORS
 :STACK-GROWS-DOWNWARD-NOT-UPWARD :SYMBOL-INFO-VOPS :UNIX
 :UNWIND-TO-FRAME-AND-CALL-VOP :X86-64)

[Stas Boukarev (stassats)]

You need to include the code to reproduce the issue.

[Stas Boukarev (stassats)]

Ok, sorry, I used a slightly older revision of 1.2.4.xx, so, it's a recent regression.

[Stas Boukarev (stassats)]

Actually, that wasn't the case, it just doesn't get triggered with safepoints enabled. But the problem is that your definition of statfs is wrong. Compare it with the definition in man statfs.
(define-alien-type statfs
  (struct statfs
          (type long)
          (bsize long)
          (blocks long)
          (bfree long)
          (bavail long)
          (files long)
          (ffree long)
          (fsid long)
          (namelen long)
          (fr-size long)
          (spare (array long 5))))

does work. But it is better to grovel the structure.

[Ken Olum (kdo)]

Huh. It failed for me also in 1.1.14. Perhaps it is very sensitive to
something.

                                        Ken

[Ken Olum (kdo)]

Ack! You're right. But it's worse than you know. My man statfs gives
the definition that I used, but it is wrong. The truth, in
/usr/include/bits/statfs.h, is just as you said.

Sorry to bother you.

                                        Ken