On Fri, 2012-07-13 at 04:21 +0900, OGAWA Hirofumi wrote: > > On Thu, 2012-07-12 at 16:28 +0200, Stevie Trujillo wrote: > >> Hello, > >> > >> I was trying to create a bootdisk to update my BIOS, and accidentially > >> made a 512byte image with only the FreeDOS header in it. > >> > >> ( Linux 3.4.4 ) > >> # mount -o loop dosdisk.img /tmp > >> ^C^C^C > >> It uses 100% CPU and doesn't listen to me when I do ^C, kill -9 etc. I > >> think this means it's stuck in the kernel? > It looks like the bug of __getblk_slow(). If requested block was beyond > end of device, __find_get_block() will find buffer_mapped()'s buffer, > but block >= end_block is unmapped. So, it can be loop. > > The following patch fixes it? If it fix, there are some options to check > it. > > a) Check it like this patch and warn. > b) (a), but without warn. > c) Check it in init_page_buffers() and return -EIO or such > > Well, anyway, Cc to Jens. > > Signed-off-by: OGAWA Hirofumi <[email protected]> > --- > > fs/buffer.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff -puN fs/buffer.c~debug fs/buffer.c > --- tux3fs/fs/buffer.c~debug 2012-07-13 04:10:40.000000000 +0900 > +++ tux3fs-hirofumi/fs/buffer.c 2012-07-13 04:11:50.000000000 +0900 > @@ -1055,6 +1055,13 @@ __getblk_slow(struct block_device *bdev, > dump_stack(); > return NULL; > } > + if (block >= blkdev_max_block(I_BDEV(bdev->bd_inode))) { > + printk(KERN_ERR "getblk(): block %llu, end_block %llu\n", > + (unsigned long long)block, > + (unsigned long > long)blkdev_max_block(I_BDEV(bdev->bd_inode))); > + dump_stack(); > + return NULL; > + } > > for (;;) { > struct buffer_head * bh; > _
This fixes the hang, but I'm not sure dump_stack() is a good idea. I get almost 100 lines of stack dumps and error messages in my kernel log. Also, I was a little surprised to see that mount completes successfully. ------------------------------------------------------------------------ Steven J. Magnani "I claim this network for MARS! www.digidescorp.com Earthling, return my space modulator!" #include <standard.disclaimer> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
