Re: current BK boot failure, d_alloc()

Jens Axboe
2003-03-24T11:51:08Z

On Mon, Mar 24 2003, Jens Axboe wrote:
> Hi,
>
> SBF: Simple Boot Flag extension found and enabled.
> SBF: Setting boot flags 0x80
> Starting balanced_irq
> Enabling SEP on CPU 1
> Enabling SEP on CPU 0
>
> Program received signal SIGSEGV, Segmentation fault.
> 0xc016da64 in d_alloc (parent=0x0, name=0xdff8fea8) at
> include/asm/string.h:196
> 196 __asm__ __volatile__(
> (gdb) bt
> #0 0xc016da64 in d_alloc (parent=0x0, name=0xdff8fea8)
> at include/asm/string.h:196
> #1 0xc016dd16 in d_alloc_root (root_inode=0xc176ddc4) at
> fs/dcache.c:787
> #2 0xc014f46b in shmem_fill_super (sb=0xc176ddc4, data=0x1, silent=0)
> at mm/shmem.c:1738
> #3 0xc015cabf in get_sb_nodev (fs_type=0x1, flags=-1049174588,
> data=0x1,
> fill_super=0xc014f330 <shmem_fill_super>) at fs/super.c:586
> #4 0xc015cc16 in do_kern_mount (fstype=0x1 <Address 0x1 out of bounds>,
> flags=1, name=0xc02c3547 "tmpfs", data=0x1) at fs/super.c:639
> #5 0xc015ccb7 in kern_mount (type=0x1) at fs/super.c:665
> #6 0xc0346620 in init_tmpfs () at mm/shmem.c:1887
> #7 0xc0338992 in do_initcalls () at init/main.c:486
> #8 0xc01050f5 in init (unused=0x0) at init/main.c:551
> (gdb) print *(struct qstr *) name
> $1 = {name = 0x0, len = 1, hash = 0, name_str = 0xdff8feb4 "\230µÿß\200µÿß"}
>
> craps out in memcpy() due to name->name == NULL

smells like a compiler problem, with the following patch:

===== fs/dcache.c 1.43 vs edited =====
--- 1.43/fs/dcache.c Sat Mar 22 05:05:21 2003
+++ edited/fs/dcache.c Mon Mar 24 12:58:19 2003
@@ -784,7 +784,8 @@
struct dentry *res = NULL;

if (root_inode) {
- res = d_alloc(NULL, &(const struct qstr) { "/", 1, 0 });
+ struct qstr name = { .name = "/", .len = 1, .hash = 0 };
+ res = d_alloc(NULL, &name);
if (res) {
res->d_sb = root_inode->i_sb;
res->d_parent = res;

--
Jens Axboe