On Thu, Jan 12, 2012 at 01:57:11PM -0800, Paul Taysom wrote: > A USB stick with a ext file system on it, would occasionally crash > when the stick was pulled. > > The problem was a timer was being set on the Backing Device Interface, > bdi, after the USB device had been removed and the bdi had been > unregistered. The bdi would then be later reinitialized by zeroing > the timer without removing from the timer from the timer queue. > This would eventually result in a kernel crash (NULL ptr dereference). > > When the bdi is unregistered, the dev field is set to NULL. This > indication is used by bdi_unregister to only unregister the device > once. > > Fix: When the backing device is invalidated, the mapping backing_dev_info > should be redirected to the default_backing_dev_info. > > Created 3 USB sticks with ext2, ext4 and one with both apple and DOS > file systems on it. Inserted and removed USB sticks many times in random > order. With out the bug fix, the kernel would soon crash. With the fix, > it did not. Ran on both stumpy and amd64-generic. > > Signed-off-by: Paul Taysom <taysom@xxxxxxxxxxxx> > Cc: Mandeep Baines <msb@xxxxxxxxxxxx> > Cc: Greg KH <greg@xxxxxxxxx> > Cc: Jens Axboe <axboe@xxxxxxxxx> > Cc: Theodore Tso <tytso@xxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxx> > Cc: <linux-usb@xxxxxxxxxxxxxxx> > Cc: <linux-kernel@xxxxxxxxxxxxxxx> > Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> > Cc: <linux-fsdevel@xxxxxxxxxxxxxxx> > Cc: <stable@xxxxxxxxxx> > --- > fs/block_dev.c | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/fs/block_dev.c b/fs/block_dev.c > index afe74dd..322cd05 100644 > --- a/fs/block_dev.c > +++ b/fs/block_dev.c > @@ -110,6 +110,7 @@ void invalidate_bdev(struct block_device *bdev) > * But, for the strange corners, lets be cautious > */ > cleancache_flush_inode(mapping); > + mapping->backing_dev_info = &default_backing_dev_info; > } > EXPORT_SYMBOL(invalidate_bdev); What ever happened to this patch? Is it still needed? Can you still reproduce the problem on Linus's tree and older kernels? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
