Re: [BUG] panic after umount (biscted)

[Jens Axboe <jens.axboe@oracle.com>]

On Fri, Oct 26 2007, Jens Axboe wrote:
> On Fri, Oct 26 2007, Sebastian Siewior wrote:
> > After umount of 
> > /dev/md/1 on /mnt/sec type xfs (rw,nosuid,nodev,noatime,nodiratime)
> > 
> > I end up with [1] on v2.6.24-rc1. It worked fine with v2.6.23. Bisec
> > came to conclusion that 
> > 
> > |fd5d806266935179deda1502101624832eacd01f is first bad commit
> > |commit fd5d806266935179deda1502101624832eacd01f
> > |Author: Jens Axboe <jens.axboe@oracle.com>
> > |Date:   Tue Oct 16 11:05:02 2007 +0200
> > |
> > |    block: convert blkdev_issue_flush() to use empty barriers
> > |    
> > |    Then we can get rid of ->issue_flush_fn() and all the driver private
> > |    implementations of that.
> > |    
> > |    Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
> > |
> > |:040000 040000 75f5c511fd785fa4c75b955f1818c382593a22ec adf460e288740ca9c0b5ab823dfc2ca04980f3d2 M      block
> > |:040000 040000 a972fe9a2433a00c79fd5ead584c482cd08b4b2c 0f4534094b63fe21c5cf8a6170736abe5c518c00 M      drivers
> > |:040000 040000 ba2a9f681826db89ba5192a7db7139baecde786a fc68a77a41d25c283f39f712216566e9b36d00fc M      include
> > 
> > is the bad boy here.
> > The last panic (with first bad commit) is [2] (there is almost no 
> > difference). My .config [3], lspci [4], bisec-log [5]. The md1 
> > raid is a
> > 
> > |Personalities : [raid1] 
> > |md1 : active raid1 sda2[1]
> > |      174843328 blocks [2/1] [_U]
> > |
> > 
> > I hope this was usefull. Now, I'm going to rebuild my raid now....
> > 
> > [1] http://download.breakpoint.cc/bug/bug_rc1.jpeg 166 KiB
> > [2] http://download.breakpoint.cc/bug/bug_last_commit.jpeg 217 KiB
> > [3] http://download.breakpoint.cc/bug/config.txt 27 KiB
> > [4] http://download.breakpoint.cc/bug/lspci.txt 2.3 KiB
> > [5] http://download.breakpoint.cc/bug/git-bisect-log.txt 2.3K
> 
> Thanks a lot, a full report on this issue. Will get this fixed up asap.

Does this work?

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 61fdaf0..cf47fcb 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1115,6 +1115,8 @@ static int scsi_init_io(struct scsi_cmnd *cmd)
 	 * kmapping pages)
 	 */
 	cmd->use_sg = req->nr_phys_segments;
+	if (!cmd->use_sg)
+		return 0;
 
 	/*
 	 * If sg table allocation fails, requeue request later.
@@ -1191,7 +1193,7 @@ int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
 	if (req->bio) {
 		int ret;
 
-		BUG_ON(!req->nr_phys_segments);
+		BUG_ON(!req->nr_phys_segments && req->bio->bi_size);
 
 		ret = scsi_init_io(cmd);
 		if (unlikely(ret))

-- 
Jens Axboe