> On Sun, 2010-11-21 at 18:57 +0100, Andi Kleen wrote: > > Alexander Kolesen <kolesen.a@xxxxxxxxx> writes: > > > > [Rafael, a new regression] > > > > > Hello. > > > I've built a kernel from > > > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git > > > (Date: Fri Nov 19 19:46:45 2010 -0800) > > > and got a kernel oops when tried to access to unplugged, > > > but mounted external usb storage formatted with JFS. > > > > Al seems to be the last person who touched it, maybe it's > > related to his changes, like this one. > > > > commit 152a08366671080f27b32e0c411ad620c5f88b57 > > Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > > Date: Sun Jul 25 00:46:55 2010 +0400 > > > > new helper: mount_bdev() > > > > ... and switch of the obvious get_sb_bdev() users to ->mount() > > > > Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > > I haven't dug too far into this yet, but I suspect that > aaead25b954879e1a708ff2f3602f494c18d20b5 is related. > > commit aaead25b954879e1a708ff2f3602f494c18d20b5 > Author: Christoph Hellwig <hch@xxxxxx> > Date: Mon Oct 4 14:25:33 2010 +0200 > > writeback: always use sb->s_bdi for writeback purposes > > I'll have to look at what happens when a device is unplugged to see if > JFS is missing something, or it's more of a generic problem. I'm open > to suggestions from anybody on cc. > > Thanks, > Shaggy > I've tested kernel before and after this commit. Yes, it reproduced after, and didn't reproduced before. > > > > > > > > Steps to reproduce: > > > mkfs.jfs /dev/sdb1 (unpluggable USB hard drive) > > > mount /dev/sdb1 /mnt/drive > > > cd /mnt/drive > > > touch test > > > sync > > > ..unplug a drive > > > ls > > > > > > > > > Result: > > > BUG: unable to handle kernel NULL pointer dereference at > > > 0000000000000020 > > > IP: __mark_inode_dirty > > > > > > Then I got a kernel coredump. Here is a stack trace: > > > > > > (gdb) bt > > > #0 __mark_inode_dirty (inode=0xffff880078fc1490, flags=<value optimized out>) at fs/fs-writeback.c:990 > > > #1 0xffffffff810e4990 in mark_inode_dirty_sync (mnt=0xffff88007862fd00, dentry=<value optimized out>) at include/linux/fs.h:1687 > > > #2 touch_atime (mnt=0xffff88007862fd00, dentry=<value optimized out>) at fs/inode.c:1505 > > > #3 0xffffffff810dfeb4 in file_accessed (file=0xffff88006afed600, filler=0xffffffff810dfcf8 <filldir>, buf=0xffff88007762bf38) at include/linux/fs.h:1763 > > > #4 vfs_readdir (file=0xffff88006afed600, filler=0xffffffff810dfcf8 <filldir>, buf=0xffff88007762bf38) at fs/readdir.c:41 > > > #5 0xffffffff810e001a in sys_getdents (fd=<value optimized out>, dirent=0x1f61468, count=32768) at fs/readdir.c:214 > > > #6 0xffffffff810279ab in ?? () at arch/x86/kernel/entry_64.S:479 > > > #7 0x00007f8b23d1a4c5 in ?? () > > > #8 0x00000000000002bb in ?? () > > > #9 0x0000000000000000 in ?? () > > > > > > (gdb) p bdi > > > $1 = (struct backing_dev_info *) 0x0 > > > > > > (gdb) p inode->i_mapping->backing_dev_info > > > $15 = (struct backing_dev_info *) 0xffff880078878d48 > > > > > > (gdb) p inode->i_sb->s_bdi > > > $16 = (struct backing_dev_info *) 0x0 > > > > > > > > > I can't do git bisect because on n'th step my system became unbootable. > > > But 2.6.35 doesn't fall. > -- > Dave Kleikamp > IBM Linux Technology Center > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
