Re: [External] Re: [PATCH 1/1] dax: Fix stack overflow when mounting fsdax pmem device

[Jan Kara <jack@suse.cz>]

On Wed 16-09-20 14:02:19, Adrian Huang12 wrote:
> > -----Original Message-----
> > From: Jan Kara <jack@suse.cz>
> > Sent: Wednesday, September 16, 2020 7:19 PM
> > >
> > > dm-3: error: dax access failed (-95)
> > > dm-3: error: dax access failed (-95)
> > > dm-3: error: dax access failed (-95)
> > 
> > Right, and that's result of the problem I also describe above. Attached patch
> > should fix these errors.
> 
> The patch introduces the following panic during boot. Apparently, the
> dax_dev is NULL in dax_supported(). So, the address 0x00000000000002d0 is
> offset of the member 'flags' in struct dax_device (the member 'flags' is
> referenced in dax_alive()):

Thanks for testing!

> The following patch solves the panic. Feel free to add it to your patch. 

I've added you fixup to the patch. Thanks for it.
 
> BTW, feel free to add my tested-by to your patch after including the following patch to your patch (I don't see any dax error messages when running lvm2-testsuite).
> Tested-by: Adrian Huang <ahuang12@lenovo.com>
> 
> Thanks for looking into the issue triggered by lvm2-testsuite.
> 
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index 0d2dcbb1e549..e84070b55463 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -325,6 +325,9 @@ EXPORT_SYMBOL_GPL(dax_direct_access);
>  bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
>                 int blocksize, sector_t start, sector_t len)
>  {
> +       if (!dax_dev)
> +               return false;
> +
>         if (!dax_alive(dax_dev))
>                 return false;
> 
> BTW, I just submitted the v2 version:
> https://lore.kernel.org/linux-nvdimm/20200916133923.31-1-adrianhuang0701@gmail.com/T/#u
> 
> Hopefully/ideally, your patch and mine can be merged at the same rc release.

Yup, I'll send it rightaway.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR
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