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Date: Thu, 30 Aug 2007 18:38:12 +0200
From: Frederik Deweerdt <deweerdt@...e.fr>
To: Rusty Russell <rusty@...tcorp.com.au>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org,
Linus Torvalds <torvalds@...ux-foundation.org>,
lguest <lguest@...abs.org>
Subject: Re: [PATCH] Fix lguest page-pinning logic ("lguest: bad stack page 0xc057a000")
On Tue, Aug 28, 2007 at 02:09:59AM +1000, Rusty Russell wrote:
> If the stack pointer is 0xc057a000, then the first stack page is at
> 0xc0579000 (the stack pointer is decremented before use). Not
> calculating this correctly caused guests with CONFIG_DEBUG_PAGEALLOC=y
> to be killed with a "bad stack page" message: the initial kernel stack
> was just preceeding the .smp_locks section which
> CONFIG_DEBUG_PAGEALLOC marks read-only when freeing.
>
Hello Rusty,
I just could try the patch, sorry for the delay. Albeit it allows to
progress a little further in the boot process, lguest seems to like that
"section that was just freed" :)
Please note that:
- It could progress to "Freeing SMP alternatives: 13k freed", which is new.
Indeed, your patch made the Host to pin 0xc04d3000, which is the
good page.
- 0xc04d4000 is the __smp_locks section:
$ objdump -h vmlinux
[...]
20 .data.init_task 00001000 c04d3000 004d3000 003d4000 2**2
CONTENTS, ALLOC, LOAD, DATA
21 .smp_locks 000036c8 c04d4000 004d4000 003d5000 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
[...]
[ 0.128503] SMP alternatives: switching to UP code
[ 0.132846] Freeing SMP alternatives: 13k freed
[ 0.135177] BUG: unable to handle kernel paging request at virtual address c04d4000
[ 0.135417] printing eip:
[ 0.135505] c01051df
[ 0.135564] *pde = 00005067
[ 0.135645] *pte = 004d4000
[ 0.135756] Oops: 0000 [#1]
[ 0.135825] PREEMPT SMP DEBUG_PAGEALLOC
[ 0.136039] Modules linked in:
[ 0.136205] CPU: 0
[ 0.136206] EIP: 0061:[<c01051df>] Not tainted VLI
[ 0.136207] EFLAGS: 00010097 (2.6.23-rc3 #5)
[ 0.136665] EIP is at dump_trace+0x5f/0x97
[ 0.136738] eax: c0614954 ebx: c04d3ffc ecx: c0497b00 edx: c04ef641
[ 0.136883] esi: c04d3000 edi: c04d3ffd ebp: c04d3da0 esp: c04d3d90
[ 0.137058] ds: 0069 es: 0069 fs: 00d8 gs: 0000 ss: 0069
[ 0.137235] Process swapper (pid: 0, ti=c04d3000 task=c04953e0 task.ti=c04d3000)
[ 0.137447] Stack: c0109d95 c0614954 c04953e0 00000000 c04d3db4 c010a1f1 c0497b00 c0614954
[ 0.137831] c0614954 c04d3dc4 c0140921 c0144252 c04959c8 c04d3dec c014272f c02eccf5
[ 0.138119] c04959c8 c0614938 c04d3dec 00000001 c04959c8 c0614938 c04953e0 c04d3e4c
[ 0.138497] Call Trace:
[ 0.138603] [<c0105231>] show_trace_log_lvl+0x1a/0x2f
[ 0.138798] [<c01052e1>] show_stack_log_lvl+0x9b/0xa3
[ 0.138942] [<c01054c1>] show_registers+0x1d8/0x30d
[ 0.139120] [<c010571d>] die+0x127/0x20a
[ 0.139272] [<c011c470>] do_page_fault+0x512/0x5e6
[ 0.139470] [<c038ec02>] error_code+0x72/0x78
[ 0.139678] [<c010a1f1>] save_stack_trace+0x23/0x3e
[ 0.139869] [<c0140921>] save_trace+0x3a/0x8e
[ 0.140049] [<c014272f>] mark_lock+0x7b/0x471
[ 0.140223] [<c01436fc>] __lock_acquire+0x51a/0xc99
[ 0.140374] [<c0143f0c>] lock_acquire+0x91/0xb5
[ 0.140546] [<c038e491>] _spin_lock_irq+0x47/0x71
[ 0.140693] [<c01354c9>] alloc_pid+0x1ce/0x22f
[ 0.140867] [<c0125ce5>] do_fork+0x15/0x1bf
[ 0.141011] [<c0102339>] kernel_thread+0x88/0x90
[ 0.141170] [<c038b2b8>] rest_init+0x14/0x63
[ 0.141345] [<c04d895e>] start_kernel+0x317/0x31f
[ 0.141565] [<c04ef641>] lguest_init+0x2af/0x2d5
[ 0.141736] BUG: unable to handle kernel paging request at virtual address c04d4000
[ 0.142195] printing eip:
[ 0.142259] c01051df
[ 0.142335] *pde = 00005067
[ 0.142418] *pte = 004d4000
[ 0.142501] Oops: 0000 [#2]
[ 0.142581] PREEMPT SMP DEBUG_PAGEALLOC
[ 0.142775] Modules linked in:
[ 0.142929] CPU: 0
[ 0.142930] EIP: 0061:[<c01051df>] Not tainted VLI
[ 0.142931] EFLAGS: 00010097 (2.6.23-rc3 #5)
[ 0.143296] EIP is at dump_trace+0x5f/0x97
[ 0.143409] eax: c0430e58 ebx: c04d3ffc ecx: c0497058 edx: 00000000
[ 0.143611] esi: c04d3000 edi: c04d3ffd ebp: c04d3c1c esp: c04d3c0c
[ 0.143800] ds: 007b es: 007b fs: 00d8 gs: 0000 ss: 0069
[ 0.143988] Process swapper (pid: 0, ti=c04d3000 task=c04953e0 task.ti=c04d3000)
[ 0.144213] Stack: 34373331 c0430e58 00000018 00000000 c04d3c30 c0105231 c0497058 c0430e58
[ 0.144634] c04d3df3 c04d3c54 c01052e1 c0430e58 c0430e58 c04d3d58 c04d3d90 00000000
[ 0.145055] 0000002b c04d3d58 c04d3cc0 c01054c1 c0430e58 00000010 c0495614 00000000
[ 0.145439] Call Trace:
[ 0.145511] [<c0105231>] show_trace_log_lvl+0x1a/0x2f
[ 0.145607] [<c01052e1>] show_stack_log_lvl+0x9b/0xa3
[ 0.145723] [<c01054c1>] show_registers+0x1d8/0x30d
[ 0.145849] [<c010571d>] die+0x127/0x20a
[ 0.145980] [<c011c470>] do_page_fault+0x512/0x5e6
[ 0.146125] [<c038ec02>] error_code+0x72/0x78
[ 0.146281] [<c0105231>] show_trace_log_lvl+0x1a/0x2f
[ 0.146423] [<c01052e1>] show_stack_log_lvl+0x9b/0xa3
[ 0.146587] [<c01054c1>] show_registers+0x1d8/0x30d
[ 0.146746] [<c010571d>] die+0x127/0x20a
[ 0.146895] [<c011c470>] do_page_fault+0x512/0x5e6
[ 0.147061] [<c038ec02>] error_code+0x72/0x78
[ 0.147213] [<c010a1f1>] save_stack_trace+0x23/0x3e
[ 0.147361] [<c0140921>] save_trace+0x3a/0x8e
[ 0.147531] [<c014272f>] mark_lock+0x7b/0x471
[ 0.147681] [<c01436fc>] __lock_acquire+0x51a/0xc99
[ 0.147839] [<c0143f0c>] lock_acquire+0x91/0xb5
[ 0.147987] [<c038e491>] _spin_lock_irq+0x47/0x71
[ 0.148136] [<c01354c9>] alloc_pid+0x1ce/0x22f
[ 0.148284] [<c0125ce5>] do_fork+0x15/0x1bf
[ 0.148458] [<c0102339>] kernel_thread+0x88/0x90
[ 0.148619] [<c038b2b8>] rest_init+0x14/0x63
[ 0.148766] [<c04d895e>] start_kernel+0x317/0x31f
[ 0.148923] [<c04ef641>] lguest_init+0x2af/0x2d5
[ 0.149076] BUG: unable to handle kernel paging request at virtual address c04d4000
[ 0.149297] printing eip:
[ 0.149371] c01051df
[ 0.149473] *pde = 00005067
[ 0.149547] *pte = 004d4000
[ 0.149623] Recursive die() failure, output suppressed
[ 0.149807] Kernel panic - not syncing: Attempted to kill the idle task!
Regards,
Frederik
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