On Sun 12-05-13 13:04:59, EUNBONG SONG wrote: > > > >> Since at this point it's safer to rollback the change and we can > >> investigate more deeply how to fix it correctly for the next > >> development cycle, this is the patch which I'm testing. > > >> - Ted > > > Hello, I've tested with your patch. But the same problem was reproduced. > > Currently, I'm trying to git bisect. If i done git bisect, i will let you know. > > Hi, I've done git bisect. and panic at jbd2_journal_put_journal_head() is caused by > ae4647fb7654676fc44a97e86eb35f9f06b99f66: "jbd2: reduce journal_head size." > I write just code patch which revert ae4647fb7654676fc44a97e86eb35f9f06b99f66 because > I don't know the root cause. This is really strange. I've verified the code and all the places modifying b_jlist or b_modified are holding bh_state lock so we should be safe... Hum, but I remember I was debugging similar problems with bit fields in btrfs on ia64 as well (see http://lwn.net/Articles/478657/). So I think what has happened is that your compiler compiled bitfield access as 64-bit and updates to b_jcount and b_jlist / b_modified crashed into one another. I didn't hit it because my compiler was not so "clever". Grumble. In this case I think bitfields are not worth the trouble with gcc. It's a pitty we have to spend additional 8 bytes for every journal_head but we'll survive... I'll send Ted a partial revert and add a comment so that we won't repeat this mistake in future. Honza > Signed-off-by: Eunbong Song <eunb.song@xxxxxxxxxxx> > --- > include/linux/journal-head.h | 11 +++++++++-- > 1 files changed, 9 insertions(+), 2 deletions(-) > > diff --git a/include/linux/journal-head.h b/include/linux/journal-head.h > index 13a3da2..c18b46f 100644 > --- a/include/linux/journal-head.h > +++ b/include/linux/journal-head.h > @@ -31,14 +31,21 @@ struct journal_head { > /* > * Journalling list for this buffer [jbd_lock_bh_state()] > */ > - unsigned b_jlist:4; > + unsigned b_jlist; > > /* > * This flag signals the buffer has been modified by > * the currently running transaction > * [jbd_lock_bh_state()] > */ > - unsigned b_modified:1; > + unsigned b_modified; > + > + /* > + * This feild tracks the last transaction id in which this buffer > + * has been cowed > + * [jbd_lock_bh_state()] > + */ > + tid_t b_cow_tid; > > /* > * Copy of the buffer data frozen for writing to the log. > -- > 1.7.0.4 > > > Thanks. -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
