Messages in this thread Patch in this message | | | Date | Fri, 27 Jan 2012 14:54:55 -0500 | From | Vivek Goyal <> | Subject | Re: Slab corruption in floppy driver module |
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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.
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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