Messages in this thread | | | From | Dirk Gouders <> | Subject | Re: Slab corruption in floppy driver module | Date | Sat, 28 Jan 2012 11:53:34 +0100 |
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Vivek Goyal <vgoyal@redhat.com> writes:
> On Fri, Jan 27, 2012 at 12:30:00PM +0100, Dirk Gouders wrote: >> Suresh Jayaraman <sjayaraman@suse.com> writes: >> >> > On 01/27/2012 03:18 AM, Dirk Gouders wrote: >> >> [snipped many lines] >> >> >> Probably a rare and uncommon one but it seems that the reloading case on >> >> a machine that has a floppy controller is a different problem. To be >> >> sure I tested the patch on a machine that has a floppy controller and >> >> when unloading and reloading the floppy module the log messages that I >> >> attached to a mail earlier in this thread are still generated. >> >> >> > >> > Yeah, this seems like a different problem. Could you please try enabling >> > CONFIG_DEBUG_PAGEALLOC and see whether is it pointing to the problem >> > code while loading/unloading the module? >> >> I enabled the option and it produces just one message during boot but >> nothing else while unloading/loading the floppy module. >> > > Can you please try following patch and see if it fixes the issue. I could > reproduce the issue with my virtual machine. The issue seems to be that > we do not call add_disk() for all the drives/disks but we try to do > put_disk() on all the disks. Hence running into the issue of putting > extra reference during module removal.
I tested your patch and it works fine.
There is just a little typo:
floppy: Fix a crash during rmmod
Thanks,
Dirk
> floppy: Fix a crash during rmmmod > > floppy driver does not call add_disk() on all the drives hence we don't take > gendisk reference on request queue for these drives. Don't call put_disk() > with disk->queue set, otherwise we try to put the reference we never took. > > Reported-by: Dirk Gouders <gouders@et.bocholt.fh-gelsenkirchen.de> > Signed-off-by: Vivek Goyal<vgoyal@redhat.com> > --- > drivers/block/floppy.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > Index: linux-2.6/drivers/block/floppy.c > =================================================================== > --- linux-2.6.orig/drivers/block/floppy.c 2012-01-27 14:34:45.000000000 -0500 > +++ linux-2.6/drivers/block/floppy.c 2012-01-27 14:39:13.729861052 -0500 > @@ -4584,6 +4584,15 @@ static void __exit floppy_module_exit(vo > platform_device_unregister(&floppy_device[drive]); > } > blk_cleanup_queue(disks[drive]->queue); > + > + /* > + * These disks have not called add_disk(). Don't put down > + * queue reference in put_disk(). > + */ > + if (!(allowed_drive_mask & (1 << drive)) || > + fdc_state[FDC(drive)].version == FDC_NONE) > + disks[drive]->queue = NULL; > + > put_disk(disks[drive]); > } >
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