On Fri 16-03-12 10:29:56, Jiri Kosina wrote: > On Fri, 16 Mar 2012, Jan Kara wrote: > > > > CPU is a Core i3 530, on a Gigabyte motherbord, 4 GB RAM. No ECC, > > > unfortunately, so I can't rule out hardware bit rot. Distribution is > > > a fairly stock Debian/unstable. > > Hmm, is any mounting & unmounting happening during your backup? Because > > the oops happened because sb->s_fs_info was NULL. Dissassembly shows: > > 16: 48 8b 47 18 mov 0x18(%rdi),%rax > > store sb->s_blocksize into RAX > > 1a: 48 8b 8f b0 02 00 00 mov 0x2b0(%rdi),%rcx > > store sb->s_fs_info into RCX > > 21: 48 c1 e8 02 shr $0x2,%rax > > This is division from EXT3_ADDR_PER_BLOCK() - RAX carries 1024 after > > division so that looks correct. > > > > 25: 48 85 db test %rbx,%rbx > > Now check passed i_block argument. > > > > 28: 41 89 c4 mov %eax,%r12d > > 2b:* 8b b1 94 00 00 00 mov 0x94(%rcx),%esi <-- trapping ins > > Try to get RCX->s_addr_per_block_bits... > > > > sb->s_fs_info is set when a superblock is mounted and cleared when > > superblock gets unmounted and otherwise it is never changed. So most likely > > it was some memory corruption clearing that pointer (I wouldn't really > > suspect HW here). > > > > It somewhat looks like the issue described here: > > http://lkml.indiana.edu/hypermail/linux/kernel/1202.3/00132.html > > > > Although there we had f_path.dentry (completely different structure) being > > NULL. But similarity here is that something stomped NULL over our existing > > structure. > > > > Linus, Jiri, that bug didn't get resolved, did it? > > I am not aware of anything, but I have a question -- George, did the > machine get suspended/resumed before this happened? And by any chance, do you use i915 driver? Because that one seems to cause corruption - see: https://lkml.org/lkml/2012/3/9/217. I believe Jiri's corruption is likely caused by that... Honza -- 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
