On Mon, 2009-03-16 at 12:28 -0500, Eric Sandeen wrote: > This is for Red Hat bug 490026, > EXT4 panic, list corruption in ext4_mb_new_inode_pa > > ext4_lock_group(sb, group) is supposed to protect this list for > each group, and a common code flow to remove an album is like > this: > > ext4_get_group_no_and_offset(sb, pa->pa_pstart, &grp, NULL); > ext4_lock_group(sb, grp); > list_del(&pa->pa_group_list); > ext4_unlock_group(sb, grp); > > so it's critical that we get the right group number back for > this prealloc context, to lock the right group (the one > associated with this pa) and prevent concurrent list manipulation. Eric, this may just be coincidence, but is it possible that this may be related to our bitmap problem I described last week? We haven't tracked it down yet but it certainly smells like a race and your fix corrects just such a race in the same code. The bitmap problem, btw, involves stuff apparently being marked as used when it's really free (or something very much like that), ultimately resulting in double frees. -- Frank Mayhar <fmayhar@xxxxxxxxxx> Google, Inc. -- 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
