Re: BUG at drivers/scsi/scsi_lib.c:1113

On 07/22/2010 10:37 AM, Neil Brown wrote:

On Thu, 22 Jul 2010 09:04:27 +0200
Jiri Slaby [off-list ref] wrote:

quoted

Hello,

I'm seeing this BUG while booting:

EXT3-fs (md1): using internal journal
------------[ cut here ]------------
kernel BUG at /home/l/latest/xxx/drivers/scsi/scsi_lib.c:1113!

You aren't the only one.
https://bugzilla.kernel.org/show_bug.cgi?id=16275

quoted

I bisected it down to:
commit 74450be123b6f3cb480c358a056be398cce6aa6e
Author: Christoph Hellwig [off-list ref]
Date:   Fri Jun 18 11:53:43 2010 +0200

    block: unify flags for struct bio and struct request

    Remove the current bio flags and reuse the request flags for the
bio, too.
    This allows to more easily trace the type of I/O from the filesystem
    down to the block driver.  There were two flags in the bio that were
    missing in the requests:  BIO_RW_UNPLUG and BIO_RW_AHEAD.  Also I've
    renamed two request flags that had a superflous RW in them.

    Note that the flags are in bio.h despite having the REQ_ name - as
    blkdev.h includes bio.h that is the only way to go for now.

    Signed-off-by: Christoph Hellwig [off-list ref]
    Signed-off-by: Jens Axboe [off-list ref]

Thanks for doing that.

I suspect that problem is that "do_sync" and "do_barriers" in
drivers/md/raid1.c are still 'bool' and should now be 'unsigned long'.

I'm not sure how wide '_Bool' is, but I'm guess it isn't wide enough.

Could you please try changing ever 'bool' in that file to 'unsigned long'
and see if that fixes it?

Please don't. This is really bad programming, and produces slower
code. You should do:

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 73cc74f..8bd1ecb 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c

@@ -787,7 +787,7 @@ static int make_request(mddev_t *mddev, struct bio * bio)
 	struct bio_list bl;
 	struct page **behind_pages = NULL;
 	const int rw = bio_data_dir(bio);
-	const bool do_sync = (bio->bi_rw & REQ_SYNC);
+	const bool do_sync = (bio->bi_rw & REQ_SYNC) != 0;
 	bool do_barriers;
 	mdk_rdev_t *blocked_rdev;
 

Boaz

Thanks,
NeilBrown