Re: FIle copy to FAT FS on NVDIMM hits BUG_ON at fs/buffer.c:3305!

On Thu, Jul 27, 2017 at 04:12:18PM +0000, Kani, Toshimitsu wrote: > On Wed, 2017-07-26 at 10:11 -0700, Matthew Wilcox wrote: > > On Wed, Jul 26, 2017 at 06:23:08PM +0900, OGAWA Hirofumi wrote: > > > The locking of this path seems to be broken. The guy familiar > > > to bdev_write_page() path will made real fix though, The > > > following patch should be explaining enough what is wrong. > > > > > > In short, clean_buffers() must be called before unlocking > > > lock_page(). > > > > Thanks for that.  This should fix the problem while not leaking > > the unlock_page call outside bdev_write_page. > > > > --- 8< --- > > > > Signed-off-by: Matthew Wilcox <mawilcox(a)microsoft.com&gt; > > Thanks Willy and Hirofumi for the quick fix!  I've tested the > change, and it works fine. > > Tested-by: Toshi Kani <toshi.kani(a)hpe.com&gt; > > Out of curiosity, I am still wondering about the following:  >  - Why is this issue exposed with FAT FS, but not with other FSs? >  - Why did I not see this issue with BTT? I also didn't see it with FAT + BRD, so I think the answer to both of the above is just that the timings were different.