Hi,
I'm getting this BUG on ~20% of boots with 2.6.39-rc5+:
[ 22.607020] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 22.608004] IP: [<ffffffffa019b8c5>] scsi_run_queue+0x24/0xe3 [scsi_mod]
[ 22.608004] PGD 22564b067 PUD 222e93067 PMD 0
[ 22.608004] Oops: 0000 [#1] SMP
[ 22.608004] last sysfs file: /sys/devices/pci0000:00/0000:00:1d.7/usb1/usb_device/usbdev1.1/dev
[ 22.608004] CPU 0
[ 22.608004] Modules linked in: megaraid_sas ide_cd_mod ib_mthca(+) cdrom ib_mad qla2xxx(+) ib_core button scsi_transport_fc scsi_tgt serio_raw ata_piix i5k_amb tpm_tis libata hwmon tpm i5000_edac floppy(+) tpm_bios scsi_mod dcdbas edac_core pcspkr uhci_hcd ehci_hcd iTCO_wdt iTCO_vendor_support rtc nfs nfs_acl auth_rpcgss fscache lockd sunrpc tg3 bnx2 e1000
[ 22.608004]
[ 22.608004] Pid: 1820, comm: path_id Not tainted 2.6.39-rc5-00139-g9fbc674 #23 Dell Inc. PowerEdge 1950/0DT097
[ 22.608004] RIP: 0010:[<ffffffffa019b8c5>] [<ffffffffa019b8c5>] scsi_run_queue+0x24/0xe3 [scsi_mod]
[ 22.608004] RSP: 0000:ffff88022fc03d10 EFLAGS: 00010282
[ 22.608004] RAX: ffff8802240ece00 RBX: ffff88022fc03d20 RCX: ffff88022f002900
[ 22.608004] RDX: 0000000000000000 RSI: 0000000000000037 RDI: 0000000000000000
[ 22.608004] RBP: ffff88022fc03d60 R08: 0000000000000286 R09: ffffea00077e33a0
[ 22.608004] R10: ffff88022f002900 R11: ffff88022fc03cf0 R12: ffff880223977740
[ 22.608004] R13: ffff8802254b2938 R14: 0000000000000000 R15: ffff880223977740
[ 22.608004] FS: 00007f2e084d26e0(0000) GS:ffff88022fc00000(0000) knlGS:0000000000000000
[ 22.608004] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 22.608004] CR2: 0000000000000000 CR3: 0000000222e03000 CR4: 00000000000006f0
[ 22.608004] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 22.608004] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 22.608004] Process path_id (pid: 1820, threadinfo ffff8802236a8000, task ffff8802234d1690)
[ 22.608004] Stack:
[ 22.608004] 0000000000000282 ffff8802254b2800 0000000000000000 ffff880223977740
[ 22.608004] ffff88022fc03d60 ffff8802240ece00 ffff880223977740 ffff8802254b2938
[ 22.608004] 0000000000000000 ffff880223977740 ffff88022fc03d90 ffffffffa019c205
[ 22.608004] Call Trace:
[ 22.608004] <IRQ>
[ 22.608004] [<ffffffffa019c205>] scsi_next_command+0x3b/0x4c [scsi_mod]
[ 22.608004] [<ffffffffa019c84a>] scsi_end_request+0x83/0x94 [scsi_mod]
[ 22.608004] [<ffffffffa019cbea>] scsi_io_completion+0x1b0/0x3fb [scsi_mod]
[ 22.608004] [<ffffffffa019b635>] ? spin_unlock_irqrestore+0xe/0x10 [scsi_mod]
[ 22.608004] [<ffffffffa0195159>] scsi_finish_command+0xeb/0xf4 [scsi_mod]
[ 22.608004] [<ffffffffa019d9df>] scsi_softirq_done+0x112/0x11b [scsi_mod]
[ 22.608004] [<ffffffff811c727e>] blk_done_softirq+0x4b/0x61
[ 22.608004] [<ffffffff8104f74c>] __do_softirq+0xbf/0x16e
[ 22.608004] [<ffffffff813b354c>] call_softirq+0x1c/0x30
[ 22.608004] [<ffffffff810041a3>] do_softirq+0x3d/0x86
[ 22.608004] [<ffffffff8104f44a>] invoke_softirq+0x17/0x20
[ 22.608004] [<ffffffff8104fa19>] irq_exit+0x57/0x98
[ 22.608004] [<ffffffff813b3c81>] do_IRQ+0x91/0xa8
[ 22.608004] [<ffffffff813abc53>] common_interrupt+0x13/0x13
[ 22.608004] <EOI>
[ 22.608004] [<ffffffff813abc9a>] ? retint_swapgs+0xe/0x13
[ 22.608004] Code: ff ff 5b 41 5c c9 c3 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 ec 28 0f 1f 44 00 00 49 89 ff 48 8b bf 40 03 00 00 48 8d 5d c0 <4c> 8b 37 48 89 5d c0 48 89 5d c8 48 8b 87 38 01 00 00 f6 80 a4
[ 22.608004] RIP [<ffffffffa019b8c5>] scsi_run_queue+0x24/0xe3 [scsi_mod]
[ 22.608004] RSP <ffff88022fc03d10>
[ 22.608004] CR2: 0000000000000000
[ 22.929460] ---[ end trace f9ecaaa16661ec4a ]---
[ 22.934070] Kernel panic - not syncing: Fatal exception in interrupt
[ 22.940410] Pid: 1820, comm: path_id Tainted: G D 2.6.39-rc5-00139-g9fbc674 #23
[ 22.948483] Call Trace:
[ 22.950923] <IRQ> [<ffffffff8104953e>] ? panic+0xbc/0x1c3
[ 22.953064] qla2xxx 0000:0e:00.0: Allocated (64 KB) for EFT...
[ 22.953217] qla2xxx 0000:0e:00.0: Allocated (1285 KB) for firmware dump...
[ 22.969169] [<ffffffff813aba57>] ? _raw_spin_unlock_irqrestore+0xe/0x10
[ 22.970176] scsi0 : qla2xxx
[ 22.970505] qla2xxx 0000:0e:00.0:
[ 22.970506] QLogic Fibre Channel HBA Driver: 8.03.07.00
[ 22.970507] QLogic QLE2462 - PCI-Express Dual Channel 4Gb Fibre Channel HBA
[ 22.970508] ISP2432: PCIe (2.5GT/s x4) @ 0000:0e:00.0 hdma+, host#=0, fw=5.03.13 (496)
[ 22.970540] qla2xxx 0000:0e:00.1: PCI INT B -> GSI 17 (level, low) -> IRQ 17
[ 23.009538] [<ffffffff81049a32>] ? spin_unlock_irqrestore+0xe/0x10
[ 23.009544] qla2xxx 0000:0e:00.1: Found an ISP2432, irq 17, iobase 0xffffc9001178c000
[ 23.009787] qla2xxx 0000:0e:00.1: irq 107 for MSI/MSI-X
[ 23.009856] qla2xxx 0000:0e:00.1: Configuring PCI space...
[ 23.009862] qla2xxx 0000:0e:00.1: setting latency timer to 64
[ 23.040006] [<ffffffff8104ada0>] ? kmsg_dump+0x4f/0xe6
[ 23.040531] qla2xxx 0000:0e:00.1: Configure NVRAM parameters...
[ 23.051121] [<ffffffff813aca70>] ? oops_end+0xaf/0xbf
[ 23.056249] [<ffffffff8102b04c>] ? no_context+0xea/0xf6
[ 23.061550] [<ffffffff8102b227>] ? __bad_area_nosemaphore+0x107/0x114
[ 23.068063] [<ffffffff8102b2be>] ? bad_area_nosemaphore+0x13/0x15
[ 23.074231] [<ffffffff813aeb28>] ? do_page_fault+0x192/0x331
[ 23.076259] qla2xxx 0000:0e:00.1: Verifying loaded RISC code...
[ 23.085867] [<ffffffff8101c7eb>] ? apic_write+0x16/0x18
[ 23.086060] qla2xxx 0000:0e:00.1: FW: Loading via request-firmware...
[ 23.097590] [<ffffffff8101ca74>] ? lapic_next_event+0x15/0x19
[ 23.103413] [<ffffffff81072fa9>] ? clockevents_program_event+0x78/0x81
[ 23.110014] [<ffffffff81074428>] ? tick_dev_program_event+0x2f/0x8e
[ 23.116357] [<ffffffff810adeae>] ? trace_hardirqs_off_caller+0x11/0x25
[ 23.122959] [<ffffffff8106bb66>] ? sched_clock_local+0x11/0x76
[ 23.128867] [<ffffffff811dd81a>] ? trace_hardirqs_off_thunk+0x3a/0x6c
[ 23.135381] [<ffffffff813abe8f>] ? page_fault+0x1f/0x30
[ 23.140692] [<ffffffffa019b8c5>] ? scsi_run_queue+0x24/0xe3 [scsi_mod]
[ 23.147300] [<ffffffffa019c205>] ? scsi_next_command+0x3b/0x4c [scsi_mod]
[ 23.154166] [<ffffffffa019c84a>] ? scsi_end_request+0x83/0x94 [scsi_mod]
[ 23.160946] [<ffffffffa019cbea>] ? scsi_io_completion+0x1b0/0x3fb [scsi_mod]
[ 23.168072] [<ffffffffa019b635>] ? spin_unlock_irqrestore+0xe/0x10 [scsi_mod]
[ 23.175283] [<ffffffffa0195159>] ? scsi_finish_command+0xeb/0xf4 [scsi_mod]
[ 23.182329] [<ffffffffa019d9df>] ? scsi_softirq_done+0x112/0x11b [scsi_mod]
[ 23.189363] [<ffffffff811c727e>] ? blk_done_softirq+0x4b/0x61
[ 23.195185] [<ffffffff8104f74c>] ? __do_softirq+0xbf/0x16e
[ 23.200745] [<ffffffff813b354c>] ? call_softirq+0x1c/0x30
[ 23.206219] [<ffffffff810041a3>] ? do_softirq+0x3d/0x86
[ 23.211519] [<ffffffff8104f44a>] ? invoke_softirq+0x17/0x20
[ 23.217167] [<ffffffff8104fa19>] ? irq_exit+0x57/0x98
[ 23.222293] [<ffffffff813b3c81>] ? do_IRQ+0x91/0xa8
[ 23.227247] [<ffffffff813abc53>] ? common_interrupt+0x13/0x13
[ 23.233067] <EOI> [<ffffffff813abc9a>] ? retint_
I get no BUGs in dozens of boots if I revert commit 86cbfb5607d:
[SCSI] put stricter guards on queue dead checks
SCSI uses request_queue->queuedata == NULL as a signal that the queue
is dying. We set this state in the sdev release function. However,
this allows a small window where we release the last reference but
haven't quite got to this stage yet and so something will try to take
a reference in scsi_request_fn and oops. It's very rare, but we had a
report here, so we're pushing this as a bug fix
The actual fix is to set request_queue->queuedata to NULL in
scsi_remove_device() before we drop the reference. This causes
correct automatic rejects from scsi_request_fn as people who hold
additional references try to submit work and prevents anything from
getting a new reference to the sdev that way.
Cc: [email protected]
Signed-off-by: James Bottomley <[email protected]>
Please let me know if what further information you need, or if there is
anything I can do, to help resolve this.
Thanks -- Jim
On Tue, 2011-05-03 at 10:53 -0600, Jim Schutt wrote:
> Please let me know if what further information you need, or if there is
> anything I can do, to help resolve this.
I think this is the fix (already in rc-fixes):
James
---
>From 3e85ea868dbd60a84240be5c1eebc36841b9c568 Mon Sep 17 00:00:00 2001
From: James Bottomley <[email protected]>
Date: Sun, 1 May 2011 09:42:07 -0500
Subject: [PATCH] [SCSI] fix oops in scsi_run_queue()
The recent commit closing the race window in device teardown:
commit 86cbfb5607d4b81b1a993ff689bbd2addd5d3a9b
Author: James Bottomley <[email protected]>
Date: Fri Apr 22 10:39:59 2011 -0500
[SCSI] put stricter guards on queue dead checks
is causing a potential NULL deref in scsi_run_queue() because the
q->queuedata may already be NULL by the time this function is called.
Since we shouldn't be running a queue that is being torn down, simply
add a NULL check in scsi_run_queue() to forestall this.
Signed-off-by: James Bottomley <[email protected]>
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index e9901b8..03979f4 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -404,6 +404,10 @@ static void scsi_run_queue(struct request_queue *q)
LIST_HEAD(starved_list);
unsigned long flags;
+ /* if the device is dead, sdev will be NULL, so no queue to run */
+ if (!sdev)
+ return;
+
if (scsi_target(sdev)->single_lun)
scsi_single_lun_run(sdev);
James Bottomley wrote:
> On Tue, 2011-05-03 at 10:53 -0600, Jim Schutt wrote:
>> Please let me know if what further information you need, or if there is
>> anything I can do, to help resolve this.
>
> I think this is the fix (already in rc-fixes):
>
> James
>
> ---
> From 3e85ea868dbd60a84240be5c1eebc36841b9c568 Mon Sep 17 00:00:00 2001
> From: James Bottomley <[email protected]>
> Date: Sun, 1 May 2011 09:42:07 -0500
> Subject: [PATCH] [SCSI] fix oops in scsi_run_queue()
>
> The recent commit closing the race window in device teardown:
>
> commit 86cbfb5607d4b81b1a993ff689bbd2addd5d3a9b
> Author: James Bottomley <[email protected]>
> Date: Fri Apr 22 10:39:59 2011 -0500
>
> [SCSI] put stricter guards on queue dead checks
>
> is causing a potential NULL deref in scsi_run_queue() because the
> q->queuedata may already be NULL by the time this function is called.
> Since we shouldn't be running a queue that is being torn down, simply
> add a NULL check in scsi_run_queue() to forestall this.
>
> Signed-off-by: James Bottomley <[email protected]>
>
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index e9901b8..03979f4 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -404,6 +404,10 @@ static void scsi_run_queue(struct request_queue *q)
> LIST_HEAD(starved_list);
> unsigned long flags;
>
> + /* if the device is dead, sdev will be NULL, so no queue to run */
> + if (!sdev)
> + return;
> +
> if (scsi_target(sdev)->single_lun)
> scsi_single_lun_run(sdev);
>
Hmmm, with the above added, I still get BUGs. Here's an
example:
[ 17.142931] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 17.143002] IP: [<ffffffffa01cf8c5>] scsi_run_queue+0x24/0xec [scsi_mod]
[ 17.143002] PGD 128257067 PUD 129da5067 PMD 0
[ 17.143002] Oops: 0000 [#1] SMP
[ 17.143002] last sysfs file: /sys/devices/platform/pcspkr/input/input0/event0/dev
[ 17.143002] CPU 1
[ 17.143002] Modules linked in: megaraid_sas ide_cd_mod cdrom button ib_mthca(+) ib_mad ib_core serio_raw floppy(+) dcdbas tpm_tis ata_piix tpm tpm_bios libata i5k_amb hwmon iTCO_wdt scsi_mod iTCO_vendor_support i5000_edac ehci_hcd pcspkr edac_core uhci_hcd rtc nfs nfs_acl auth_rpcgss fscache lockd sunrpc tg3 bnx2 e1000
[ 17.143002]
[ 17.143002] Pid: 1751, comm: path_id Not tainted 2.6.39-rc5-00140-g6a9a2d5 #24 Dell Inc. PowerEdge 1950/0DT097
[ 17.143002] RIP: 0010:[<ffffffffa01cf8c5>] [<ffffffffa01cf8c5>] scsi_run_queue+0x24/0xec [scsi_mod]
[ 17.143002] RSP: 0000:ffff88012fc43d10 EFLAGS: 00010246
[ 17.143002] RAX: ffff880127393700 RBX: ffff880127393700 RCX: ffff88012f002900
[ 17.143002] RDX: 0000000000000000 RSI: 0000000000000037 RDI: 0000000000000000
[ 17.143002] RBP: ffff88012fc43d60 R08: 0000000000000286 R09: ffffea00040947f0
[ 17.143002] R10: ffff88012f002900 R11: ffff88012fc43cf0 R12: ffff880126cdcf80
[ 17.143002] R13: ffff880126d45138 R14: 0000000000000000 R15: ffff880126cdcf80
[ 17.143002] FS: 0000000000000000(0000) GS:ffff88012fc40000(0000) knlGS:0000000000000000
[ 17.143002] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 17.143002] CR2: 0000000000000000 CR3: 0000000126d0f000 CR4: 00000000000006e0
[ 17.143002] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 17.143002] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 17.143002] Process path_id (pid: 1751, threadinfo ffff880127a10000, task ffff880129c02d20)
[ 17.143002] Stack:
[ 17.143002] 0000000000000282 ffff880126cdcf80 0000000000000000 ffff880126cdcf80
[ 17.143002] ffff88012fc43d60 ffff880127393700 ffff880126cdcf80 ffff880126d45138
[ 17.143002] 0000000000000000 ffff880126cdcf80 ffff88012fc43d90 ffffffffa01d020e
[ 17.143002] Call Trace:
[ 17.143002] <IRQ>
[ 17.143002] [<ffffffffa01d020e>] scsi_next_command+0x3b/0x4c [scsi_mod]
[ 17.143002] [<ffffffffa01d0853>] scsi_end_request+0x83/0x94 [scsi_mod]
[ 17.143002] [<ffffffffa01d0bf3>] scsi_io_completion+0x1b0/0x3fb [scsi_mod]
[ 17.143002] [<ffffffffa01cf635>] ? spin_unlock_irqrestore+0xe/0x10 [scsi_mod]
[ 17.143002] [<ffffffffa01c9159>] scsi_finish_command+0xeb/0xf4 [scsi_mod]
[ 17.143002] [<ffffffffa01d19e8>] scsi_softirq_done+0x112/0x11e [scsi_mod]
[ 17.143002] [<ffffffff811c727e>] blk_done_softirq+0x4b/0x61
[ 17.143002] [<ffffffff8104f74c>] __do_softirq+0xbf/0x16e
[ 17.143002] [<ffffffff813b354c>] call_softirq+0x1c/0x30
[ 17.143002] [<ffffffff810041a3>] do_softirq+0x3d/0x86
[ 17.143002] [<ffffffff8104f44a>] invoke_softirq+0x17/0x20
[ 17.143002] [<ffffffff8104fa19>] irq_exit+0x57/0x98
[ 17.143002] [<ffffffff813b3c81>] do_IRQ+0x91/0xa8
[ 17.143002] [<ffffffff813abc53>] common_interrupt+0x13/0x13
[ 17.143002] <EOI>
[ 17.143002] [<ffffffff811078c0>] ? kmem_cache_create+0x175/0x175
[ 17.143002] [<ffffffff810eeb06>] ? anon_vma_alloc+0x1a/0x2b
[ 17.143002] [<ffffffff810eec0a>] anon_vma_prepare+0x60/0xfe
[ 17.143002] [<ffffffff810e2f59>] __do_fault+0xc8/0x360
[ 17.143002] [<ffffffff810e3227>] do_linear_fault+0x36/0x38
[ 17.143002] [<ffffffff8102ea08>] ? pgtable_page_ctor+0x1a/0x1c
[ 17.143002] [<ffffffff810e4112>] handle_pte_fault+0x6a/0x170
[ 17.143002] [<ffffffff810e2a1e>] ? spin_lock+0xe/0x10
[ 17.143002] [<ffffffff810e56e6>] handle_mm_fault+0x15f/0x177
[ 17.143002] [<ffffffff813aebda>] do_page_fault+0x244/0x331
[ 17.143002] [<ffffffff810eb086>] ? do_mmap_pgoff+0x267/0x2cc
[ 17.143002] [<ffffffff810adeae>] ? trace_hardirqs_off_caller+0x11/0x25
[ 17.143002] [<ffffffff811dd81a>] ? trace_hardirqs_off_thunk+0x3a/0x6c
[ 17.143002] [<ffffffff813abe8f>] page_fault+0x1f/0x30
[ 17.143002] Code: ff ff 5b 41 5c c9 c3 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 ec 28 0f 1f 44 00 00 48 89 7d b8 48 8b bf 40 03 00 00 48 85 ff <4c> 8b 37 0f 84 b0 00 00 00 48 8d 5d c0 48 89 5d c0 48 89 5d c8
[ 17.143002] RIP [<ffffffffa01cf8c5>] scsi_run_queue+0x24/0xec [scsi_mod]
[ 17.143002] RSP <ffff88012fc43d10>
[ 17.143002] CR2: 0000000000000000
[ 17.535741] ---[ end trace 97dde672b920540a ]---
Please let me know what else I can do to help sort this out.
-- Jim
On Tue, 2011-05-03 at 11:27 -0600, Jim Schutt wrote:
> James Bottomley wrote:
> > On Tue, 2011-05-03 at 10:53 -0600, Jim Schutt wrote:
> >> Please let me know if what further information you need, or if there is
> >> anything I can do, to help resolve this.
> >
> > I think this is the fix (already in rc-fixes):
> >
> > James
> >
> > ---
> > From 3e85ea868dbd60a84240be5c1eebc36841b9c568 Mon Sep 17 00:00:00 2001
> > From: James Bottomley <[email protected]>
> > Date: Sun, 1 May 2011 09:42:07 -0500
> > Subject: [PATCH] [SCSI] fix oops in scsi_run_queue()
> >
> > The recent commit closing the race window in device teardown:
> >
> > commit 86cbfb5607d4b81b1a993ff689bbd2addd5d3a9b
> > Author: James Bottomley <[email protected]>
> > Date: Fri Apr 22 10:39:59 2011 -0500
> >
> > [SCSI] put stricter guards on queue dead checks
> >
> > is causing a potential NULL deref in scsi_run_queue() because the
> > q->queuedata may already be NULL by the time this function is called.
> > Since we shouldn't be running a queue that is being torn down, simply
> > add a NULL check in scsi_run_queue() to forestall this.
> >
> > Signed-off-by: James Bottomley <[email protected]>
> >
> > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> > index e9901b8..03979f4 100644
> > --- a/drivers/scsi/scsi_lib.c
> > +++ b/drivers/scsi/scsi_lib.c
> > @@ -404,6 +404,10 @@ static void scsi_run_queue(struct request_queue *q)
> > LIST_HEAD(starved_list);
> > unsigned long flags;
> >
> > + /* if the device is dead, sdev will be NULL, so no queue to run */
> > + if (!sdev)
> > + return;
> > +
> > if (scsi_target(sdev)->single_lun)
> > scsi_single_lun_run(sdev);
> >
>
> Hmmm, with the above added, I still get BUGs. Here's an
> example:
>
> [ 17.142931] BUG: unable to handle kernel NULL pointer dereference at (null)
> [ 17.143002] IP: [<ffffffffa01cf8c5>] scsi_run_queue+0x24/0xec [scsi_mod]
Ooh, compiler optimisation, I think; try this instead
James
---
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index e9901b8..0bac91e 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -400,10 +400,15 @@ static inline int scsi_host_is_busy(struct Scsi_Host *shost)
static void scsi_run_queue(struct request_queue *q)
{
struct scsi_device *sdev = q->queuedata;
- struct Scsi_Host *shost = sdev->host;
+ struct Scsi_Host *shost;
LIST_HEAD(starved_list);
unsigned long flags;
+ /* if the device is dead, sdev will be NULL, so no queue to run */
+ if (!sdev)
+ return;
+
+ shost = sdev->host;
if (scsi_target(sdev)->single_lun)
scsi_single_lun_run(sdev);
James Bottomley wrote:
> On Tue, 2011-05-03 at 11:27 -0600, Jim Schutt wrote:
>> James Bottomley wrote:
>>> On Tue, 2011-05-03 at 10:53 -0600, Jim Schutt wrote:
>>>> Please let me know if what further information you need, or if there is
>>>> anything I can do, to help resolve this.
>>> I think this is the fix (already in rc-fixes):
>>>
>>> James
>>>
>>> ---
>>> From 3e85ea868dbd60a84240be5c1eebc36841b9c568 Mon Sep 17 00:00:00 2001
>>> From: James Bottomley <[email protected]>
>>> Date: Sun, 1 May 2011 09:42:07 -0500
>>> Subject: [PATCH] [SCSI] fix oops in scsi_run_queue()
>>>
>>> The recent commit closing the race window in device teardown:
>>>
>>> commit 86cbfb5607d4b81b1a993ff689bbd2addd5d3a9b
>>> Author: James Bottomley <[email protected]>
>>> Date: Fri Apr 22 10:39:59 2011 -0500
>>>
>>> [SCSI] put stricter guards on queue dead checks
>>>
>>> is causing a potential NULL deref in scsi_run_queue() because the
>>> q->queuedata may already be NULL by the time this function is called.
>>> Since we shouldn't be running a queue that is being torn down, simply
>>> add a NULL check in scsi_run_queue() to forestall this.
>>>
>>> Signed-off-by: James Bottomley <[email protected]>
>>>
>>> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
>>> index e9901b8..03979f4 100644
>>> --- a/drivers/scsi/scsi_lib.c
>>> +++ b/drivers/scsi/scsi_lib.c
>>> @@ -404,6 +404,10 @@ static void scsi_run_queue(struct request_queue *q)
>>> LIST_HEAD(starved_list);
>>> unsigned long flags;
>>>
>>> + /* if the device is dead, sdev will be NULL, so no queue to run */
>>> + if (!sdev)
>>> + return;
>>> +
>>> if (scsi_target(sdev)->single_lun)
>>> scsi_single_lun_run(sdev);
>>>
>> Hmmm, with the above added, I still get BUGs. Here's an
>> example:
>>
>> [ 17.142931] BUG: unable to handle kernel NULL pointer dereference at (null)
>> [ 17.143002] IP: [<ffffffffa01cf8c5>] scsi_run_queue+0x24/0xec [scsi_mod]
>
> Ooh, compiler optimisation, I think; try this instead
>
> James
>
> ---
>
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index e9901b8..0bac91e 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -400,10 +400,15 @@ static inline int scsi_host_is_busy(struct Scsi_Host *shost)
> static void scsi_run_queue(struct request_queue *q)
> {
> struct scsi_device *sdev = q->queuedata;
> - struct Scsi_Host *shost = sdev->host;
> + struct Scsi_Host *shost;
> LIST_HEAD(starved_list);
> unsigned long flags;
>
> + /* if the device is dead, sdev will be NULL, so no queue to run */
> + if (!sdev)
> + return;
> +
> + shost = sdev->host;
> if (scsi_target(sdev)->single_lun)
> scsi_single_lun_run(sdev);
>
Yes, that definitely fixes things for me.
Thanks!!
-- Jim
Hi James,
FWIW, I noticed that commit 99f3c722e23 in scsi-rc-fixes-2.6
might want a Cc: [email protected], since the commit it's
fixing, 86cbfb5607d4, had one.
I'm not sure how that all works, but I thought I'd mention it
just in case.
-- Jim
On Tue, 2011-05-03 at 12:52 -0600, Jim Schutt wrote:
> FWIW, I noticed that commit 99f3c722e23 in scsi-rc-fixes-2.6
> might want a Cc: [email protected], since the commit it's
> fixing, 86cbfb5607d4, had one.
>
> I'm not sure how that all works, but I thought I'd mention it
> just in case.
Yes, good point; I'll add it ... destabilising the stable kernels
wouldn't be a very good idea.
James