On Fri, 14 Nov 2014 09:49:07 +0900 Minchan Kim <minchan@xxxxxxxxxx> wrote: > When I tested zram, I found processes got segfaulted. > The reason was zram_rw_page doesn't make the page dirty > again when swap write failed, and even it doesn't return > error by [1]. > > If error by zram internal happens, zram_rw_page should return > non-zero without calling page_endio. > It causes resubmit the IO with bio so that it ends up calling > bio->bi_end_io. > > The reason is zram could be used for a block device for FS and > swap, which they uses different bio complete callback, which > works differently. So, we should rely on the bio I/O complete > handler rather than zram_bvec_rw itself in case of I/O fail. > > This patch fixes the segfault issue as well one [1]'s > mentioned > > ... > > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -978,12 +978,10 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector, > out_unlock: > up_read(&zram->init_lock); > out: > - page_endio(page, rw, err); > + if (unlikely(err)) > + return err; > > - /* > - * Return 0 prevents I/O fallback trial caused by rw_page fail > - * and upper layer can handle this IO error via page error. > - */ > + page_endio(page, rw, 0); > return 0; Losing the comment makes me sad. The code is somewhat odd-looking. We should add some words explaining why we're not reporting errors at this point. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>