Messages in this thread | | | Date | Tue, 3 May 2011 11:54:39 -0600 | From | "Jim Schutt" <> | Subject | Re: 2.6.39-rc5+ BUG at scsi_run_queue+0x24/0xe3 |
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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 <James.Bottomley@suse.de> >>> 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 <James.Bottomley@suse.de> >>> 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 <James.Bottomley@suse.de> >>> >>> 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
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