Re: soft lock failure on FC8

[Andrew Morton <akpm@linux-foundation.org>]

On Mon, 4 Feb 2008 17:52:16 +0530 "Dragon kumar" <disaster2008@gmail.com> wrote:

> Hi Andrew,
> 
> I am not able to boot 2.6.24-mm1 kernel on x86_64 machine with FC8. I
> am attaching config file and call trace also with this mail.
> 
> 
> [  921.273592] BUG: soft lockup - CPU#0 stuck for 61s! [scsi_scan_0:473]
> [  921.273601] CPU 0:
> [  921.273601] Modules linked in: scsi_wait_scan tg3 shpchp
> pci_hotplug aacraid sd_mod scsi_mod ext3 jbd mbcache uhci_hcd ohci_hcd
> ssb ehci_hcd usbcore
> [  921.273601] Pid: 473, comm: scsi_scan_0 Not tainted 2.6.24-mm1-autokern1 #1
> [  921.273601] RIP: 0010:[<ffffffff8031fa1b>]  [<ffffffff8031fa1b>]
> radix_tree_gang_lookup+0xe1/0x139
> [  921.273601] RSP: 0018:ffff81007d99bda8  EFLAGS: 00000293
> [  921.273601] RAX: 0000000000000000 RBX: ffff81007d99bde0 RCX: 0000000000000000
> [  921.273601] RDX: 0000000000000000 RSI: ffff81007d8f2690 RDI: 000000000000000c
> [  921.273601] RBP: 0000000000000001 R08: ffff81007d8dce0c R09: 0000000000000001
> [  921.273601] R10: ffff81007d90caf0 R11: 000000000000000d R12: ffff81000106ac00
> [  921.273601] R13: ffff8100808ed000 R14: ffff81007d99a000 R15: ffffffff8077eef0
> [  921.273601] FS:  0000000000000000(0000) GS:ffffffff8057e000(0000)
> knlGS:0000000000000000
> [  921.273601] CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
> [  921.273601] CR2: 00000000006167d0 CR3: 0000000000201000 CR4: 00000000000006e0
> [  921.273601] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [  921.273601] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [  921.273601]
> [  921.273601] Call Trace:
> [  921.273601]  [<ffffffff8031870d>] ? call_for_each_cic+0x72/0x104
> [  921.273601]  [<ffffffff80318e84>] ? cfq_exit_single_io_context+0x0/0x4e
> [  921.273601]  [<ffffffff803187b7>] ? cfq_exit_io_context+0x18/0x1a
> [  921.273601]  [<ffffffff80311844>] ? exit_io_context+0x101/0x111
> [  921.273601]  [<ffffffff80239e53>] ? do_exit+0x794/0x7c1
> [  921.273601]  [<ffffffff8020d03f>] ? child_rip+0x11/0x12
> [  921.273601]  [<ffffffff8020c703>] ? restore_args+0x0/0x30
> [  921.273601]  [<ffffffff80249c5d>] ? kthreadd+0x17d/0x1a2
> [  921.273601]  [<ffffffff80249da9>] ? kthread+0x0/0x77
> [  921.273601]  [<ffffffff8020d02e>] ? child_rip+0x0/0x12
> [  921.273601]
> 

At a guess I'd say that call_for_each_cic() is failing to advance across
the radix-tree and got stuck.

Could you please apply this debug patch and retest?

Thanks.

diff -puN block/cfq-iosched.c~a block/cfq-iosched.c
--- a/block/cfq-iosched.c~a
+++ a/block/cfq-iosched.c
@@ -1159,6 +1159,7 @@ call_for_each_cic(struct io_context *ioc
 
 	do {
 		int i;
+		unsigned long next_index;
 
 		/*
 		 * Perhaps there's a better way - this just gang lookups from
@@ -1171,8 +1172,13 @@ call_for_each_cic(struct io_context *ioc
 			break;
 
 		called += nr;
-		index = 1 + (unsigned long) cics[nr - 1]->key;
-
+		next_index = 1 + (unsigned long) cics[nr - 1]->key;
+		if (next_index <= index) {
+			printk("next_index=%lu, index=%lu\n",
+				next_index, index);
+			dump_stack();
+		}
+		index = next_index;
 		for (i = 0; i < nr; i++)
 			func(ioc, cics[i]);
 	} while (nr == CIC_GANG_NR);
_