On Mon, Dec 03, 2007 at 11:34:59AM -0800, Andrew Morton wrote:
...
> Strange. It _looks_ like we've somehow caused smp_processor_id() to return
> a not-possible CPU number.
...
> Could you debug this a bit please? Find out which CPU number
> __percpu_counter_add() is using, for a start? I'd do:
...
> Alternatively, just do
>
> if (!cpu_possible(cpu))
> printk(...)
>
> in __percpu_counter_add(). Then you can proceed to work through the
> various operations which smp_processor_id() does and find out where it went
> wrong: print out %fs, mainly.
>
> If the cpu number is valid then perhaps something scribbled on the cpu's
> per-cpu memory.
I'll keep looking at this, but at a glance it looks like the cpu
number is valid, because I don't trip a BUG_ON when I make the change
below (the badval variable is noise, sorry).
--- lx/lib/percpu_counter.c.20071130 2007-12-03 15:43:19.000000000 -0500
+++ lx/lib/percpu_counter.c 2007-12-03 15:47:38.000000000 -0500
@@ -33,7 +33,9 @@ void __percpu_counter_add(struct percpu_
s64 count;
s32 *pcount;
int cpu = get_cpu();
+ u64 badval = 0xffffffffffffffffULL;
+ BUG_ON(!cpu_possible(cpu));
pcount = per_cpu_ptr(fbc->counters, cpu);
count = *pcount + amount;
if (count >= batch || count <= -batch) {
The trace is,
Unable to handle kernel paging request at ffffffffffffffff RIP:
[<ffffffff8036d602>] __percpu_counter_add+0x35/0x7f
PGD 203067 PUD 204067 PMD 0
Oops: 0000 [1] SMP
CPU 0
Modules linked in: aoe
Pid: 2777, comm: bash Not tainted 2.6.24-rc3-47dbg #9
RIP: 0010:[<ffffffff8036d602>] [<ffffffff8036d602>]
__percpu_counter_add+0x35/0x7f
RSP: 0018:ffff810078d19aa8 EFLAGS: 00010086
RAX: ffffffffffffffff RBX: ffff81007fc71950 RCX: 0000000000000010
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff810078d9a250
RBP: ffff810078d19ac8 R08: ffff81007cc077b0 R09: ffffffff802ae5ee
R10: ffff810078d19aa8 R11: ffff810078cb59d8 R12: ffff81007c81c380
R13: ffff810078d9a250 R14: 0000000000000200 R15: ffff81007805f830
FS: 00002b341db94db0(0000) GS:ffffffff8078b000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: ffffffffffffffff CR3: 000000007b415000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process bash (pid: 2777, threadinfo ffff810078d18000, task ffff810078d160c0)
Stack: ffff810078d19ac8 ffff81007fc71950 ffff81007c81c380 0000000000000000
ffff810078d19af8 ffffffff802ae682 0000100078d19ae8 ffff81007805f830
0000000000000200 ffff81007fc71950 ffff810078d19b18 ffffffff802ae75c
Call Trace:
[<ffffffff802ae682>] __set_page_dirty+0xdc/0x121
[<ffffffff802ae75c>] mark_buffer_dirty+0x95/0x99
[<ffffffff802ae7d2>] __block_commit_write+0x72/0xac
[<ffffffff802ae988>] block_write_end+0x4f/0x5b
[<ffffffff802b243f>] blkdev_write_end+0x1b/0x38
[<ffffffff80265d96>] generic_file_buffered_write+0x1c0/0x648
[<ffffffff8023a752>] current_fs_time+0x22/0x29
[<ffffffff80266576>] __generic_file_aio_write_nolock+0x358/0x3c2
[<ffffffff80266c84>] filemap_fault+0x1c4/0x320
[<ffffffff80264cce>] unlock_page+0x2d/0x31
[<ffffffff802666dd>] generic_file_aio_write_nolock+0x3b/0x8d
[<ffffffff8028e40f>] do_sync_write+0xe2/0x126
[<ffffffff802497d0>] autoremove_wake_function+0x0/0x38
[<ffffffff8058e715>] do_page_fault+0x3f8/0x7bb
[<ffffffff8028cae8>] fd_install+0x5f/0x68
[<ffffffff8028eb98>] vfs_write+0xae/0x137
[<ffffffff8028f102>] sys_write+0x47/0x70
[<ffffffff8020b7ae>] system_call+0x7e/0x83
Code: 4c 8b 24 d0 49 63 04 24 48 8d 1c 30 48 63 c1 48 39 c3 7d 0a
RIP [<ffffffff8036d602>] __percpu_counter_add+0x35/0x7f
RSP <ffff810078d19aa8>
CR2: ffffffffffffffff
BUG: sleeping function called from invalid context at kernel/rwsem.c:20
in_atomic():0, irqs_disabled():1
INFO: lockdep is turned off.
Call Trace:
[<ffffffff802518cb>] debug_show_held_locks+0x1b/0x24
[<ffffffff8022f352>] __might_sleep+0xc7/0xc9
[<ffffffff8024c4d0>] down_read+0x1d/0x4a
[<ffffffff80237bd8>] exit_mm+0x34/0xf7
[<ffffffff8023933e>] do_exit+0x247/0x75b
[<ffffffff8058e9e4>] do_page_fault+0x6c7/0x7bb
[<ffffffff8058a82a>] thread_return+0x42/0x86
[<ffffffff88002544>] :aoe:aoeblk_make_request+0x1c3/0x1d0
[<ffffffff8058cb7d>] error_exit+0x0/0x9a
[<ffffffff802ae5ee>] __set_page_dirty+0x48/0x121
[<ffffffff8036d602>] __percpu_counter_add+0x35/0x7f
[<ffffffff802ae682>] __set_page_dirty+0xdc/0x121
[<ffffffff802ae75c>] mark_buffer_dirty+0x95/0x99
[<ffffffff802ae7d2>] __block_commit_write+0x72/0xac
[<ffffffff802ae988>] block_write_end+0x4f/0x5b
[<ffffffff802b243f>] blkdev_write_end+0x1b/0x38
[<ffffffff80265d96>] generic_file_buffered_write+0x1c0/0x648
[<ffffffff8023a752>] current_fs_time+0x22/0x29
[<ffffffff80266576>] __generic_file_aio_write_nolock+0x358/0x3c2
[<ffffffff80266c84>] filemap_fault+0x1c4/0x320
[<ffffffff80264cce>] unlock_page+0x2d/0x31
[<ffffffff802666dd>] generic_file_aio_write_nolock+0x3b/0x8d
[<ffffffff8028e40f>] do_sync_write+0xe2/0x126
[<ffffffff802497d0>] autoremove_wake_function+0x0/0x38
[<ffffffff8058e715>] do_page_fault+0x3f8/0x7bb
[<ffffffff8028cae8>] fd_install+0x5f/0x68
[<ffffffff8028eb98>] vfs_write+0xae/0x137
[<ffffffff8028f102>] sys_write+0x47/0x70
[<ffffffff8020b7ae>] system_call+0x7e/0x83
--
Ed L Cashin <[EMAIL PROTECTED]>
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