On Mon, 30 Nov 2009 21:34:14 -0500 Amerigo Wang <amwang@xxxxxxxxxx> wrote: > > This BUG() is suspicious, it makes its following statements > unreachable, and it seems to be useless, since the caller > of this function already handles the failure properly. > Remove it. > > Signed-off-by: WANG Cong <amwang@xxxxxxxxxx> > Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> > Cc: Jens Axboe <jens.axboe@xxxxxxxxxx> > Cc: Nick Piggin <npiggin@xxxxxxx> > Cc: "Theodore Ts'o" <tytso@xxxxxxx> > > --- > diff --git a/fs/buffer.c b/fs/buffer.c > index 6fa5302..ac111d7 100644 > --- a/fs/buffer.c > +++ b/fs/buffer.c > @@ -1041,7 +1041,6 @@ grow_dev_page(struct block_device *bdev, sector_t block, > return page; > > failed: > - BUG(); > unlock_page(page); > page_cache_release(page); > return NULL; The caller doesn't handle this properly. If we return zero here, grow_buffers() will say sheesh and will retry and the kernel goes into an infinite retry loop. If there is a blockdev page which is sitting in pagecache and for some reason it has buffers and we cannot release them, we're kind of stuck and don't know what to do. Going BUG() is a decent thing to do here. I don't think I've ever seen a report of the BUG triggering. It could happen as a result of memory corruption or a missed bh_put() or whatever. I think a better patch would be to remove the unlock_page()/page_cache_release(), add a comment (culled from the above) and leave the BUG() there. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
