Hello, On (04/15/17 00:33), Minchan Kim wrote: > On Fri, Apr 14, 2017 at 02:07:47PM +0900, Sergey Senozhatsky wrote: > > On (04/13/17 09:17), Minchan Kim wrote: > > [..] > > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > > > index 9e2199060040..83c38a123242 100644 > > > --- a/drivers/block/zram/zram_drv.c > > > +++ b/drivers/block/zram/zram_drv.c > > > @@ -930,7 +930,7 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector, > > > } > > > > > > index = sector >> SECTORS_PER_PAGE_SHIFT; > > > - offset = sector & (SECTORS_PER_PAGE - 1) << SECTOR_SHIFT; > > > + offset = (sector & (SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT; > > > > sorry, can it actually produce different results? > > I got your point. Actually, offset was wrong but rw_page is called > with PAGE_SIZE io while that offset is related to only partial io > (non-PAGEE size io). IOW, although the wrong offset it is never used > in functions. > > To find subtle corruption in ppc64, I added some debug code to > catch up wrong buffer overflow and found it with other bugs but > didn't prove the specific case is valid case or not. Good catch, Sergey! > > However, it should be *fixed* to prevent confusion in future but surely, > no need to go to the stable. I will send reply to Greg to prevent merging > it to *stable* when he send review asking to merge. cool. thanks! > And next week I will send another fix which *maybe* removes code to get the > offset in zram_rw_page. sounds interesting! -ss