[parisc-linux] kernel BUG at include/asm/mmzone.h:74!

[parisc-linux] kernel BUG at include/asm/mmzone.h:74!

[Helge Deller]

I'm now running into this problem when trying to start X11, either with the VisEG stifb or sstfb driver.

Linux version 2.6.7-pa10 (root@p100) (gcc version 3.0.2 20010829 (prerelease)) #52 Sat Jul 10 12:13:50 CEST 2004

Machine: c3k, Kernel 2.6.7-pa10, 32bit kernel.

kernel BUG at include/asm/mmzone.h:74!
Kernel addresses on the stack:
 [<10128b94>] printk+0x108/0x184
 [<10107ee8>] dump_stack+0x18/0x24
 [<10154ab8>] remap_page_range+0x198/0x47c
 [<10166a24>] do_sync_write+0x74/0xa8
 [<102932f0>] fb_mmap+0x11c/0x130
 [<10158594>] do_mmap_pgoff+0x3b8/0x680
 [<10166ae4>] vfs_write+0x8c/0x138
 [<1010f2b4>] do_mmap2+0x74/0xdc
 [<1016615c>] sys_open+0x84/0xa8
 [<1010a35c>] tracesys_exit+0x0/0x34
 [<1010d088>] intr_check_sig+0x0/0xc

Is it maybe related to the latest CONFIG_DISCONTIGMEM or arch/parisc/mm/init.c changes ?

Helge
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Re: [parisc-linux] kernel BUG at include/asm/mmzone.h:74!

[Randolph Chung]

In reference to a message from Helge Deller, dated Jul 10:
> I'm now running into this problem when trying to start X11, either with the VisEG stifb or sstfb driver.

this is because mmio space is not handled properly by the discontigmem
support...

this patch should "fix" it, but i'm not completely happy with this 
approach.  will think about it some more. it won't work on 64-bit 
platforms because pfn_is_io() is wrong there....

you don't need CONFIG_DISCONTIGMEM on c3000, so you can also just 
disable that :)

Index: include/asm-parisc/mmzone.h
===================================================================
RCS file: /var/cvs/linux-2.6/include/asm-parisc/mmzone.h,v
retrieving revision 1.2
diff -u -p -r1.2 mmzone.h
--- include/asm-parisc/mmzone.h	9 Jul 2004 19:04:21 -0000	1.2
+++ include/asm-parisc/mmzone.h	10 Jul 2004 17:03:25 -0000
@@ -64,10 +64,16 @@ extern struct node_map_data node_data[];
 #define PFNNID_MAP_MAX  512     /* support 512GB */
 extern unsigned char pfnnid_map[PFNNID_MAP_MAX];
 
+#define pfn_is_io(pfn) ((pfn & (0xf0000000 >> PAGE_SHIFT)) == (0xf0000000 >> PAGE_SHIFT))
+
 static inline int pfn_to_nid(unsigned long pfn)
 {
 	unsigned int i;
 	unsigned char r;
+
+	if (unlikely(pfn_is_io(pfn)))
+		return 0;
+
 	i = pfn >> PFNNID_SHIFT;
 	BUG_ON(i >= sizeof(pfnnid_map) / sizeof(pfnnid_map[0]));
 	r = pfnnid_map[i];


randolph
-- 
Randolph Chung
Debian GNU/Linux Developer, hppa/ia64 ports
http://www.tausq.org/

Re: [parisc-linux] kernel BUG at include/asm/mmzone.h:74!

[Helge Deller]

Hi tausq,

On Saturday 10 July 2004 19:16, Randolph Chung wrote:
> In reference to a message from Helge Deller, dated Jul 10:
> > I'm now running into this problem when trying to start X11, either with the VisEG stifb or sstfb driver.
> 
> this is because mmio space is not handled properly by the discontigmem
> support...
> 
> this patch should "fix" it, but i'm not completely happy with this 
> approach.  will think about it some more. it won't work on 64-bit 
> platforms because pfn_is_io() is wrong there....

The patch you committed for 2.6.7-pa12 worked on my c3k.
Thanks for fixing !

Helge
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