On 4/23/21 2:38 PM, Bart Van Assche wrote:

Hi Changheun,

If I run blktest srp/001 then a kernel warning appears that I haven't
seen before. I think this is a side-effect of the patch that limits the
bio size. Please take a look.

Thanks,

Bart.

WARNING: CPU: 1 PID: 15449 at block/bio.c:1034
__bio_iov_iter_get_pages+0x324/0x350
Call Trace:
 bio_iov_iter_get_pages+0x6c/0x360
 __blkdev_direct_IO_simple+0x291/0x580
 blkdev_direct_IO+0xb5/0xc0
 generic_file_direct_write+0x10d/0x290
 __generic_file_write_iter+0x120/0x290
 blkdev_write_iter+0x16e/0x280
 new_sync_write+0x268/0x380
 vfs_write+0x3e0/0x4f0
 ksys_write+0xd9/0x180
 __x64_sys_write+0x43/0x50
 do_syscall_64+0x32/0x80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

I wonder if this is a case of violating "must always be able to add a page"?
Bart, does the below change anything?

diff --git a/include/linux/bio.h b/include/linux/bio.h
index f1a99f0a240c..c6428c9f9bf7 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h

@@ -121,7 +121,8 @@ static inline bool bio_full(struct bio *bio, unsigned len)
 	if (bio->bi_vcnt >= bio->bi_max_vecs)
 		return true;
 
-	if (bio->bi_iter.bi_size > bio_max_size(bio) - len)
+	if (bio->bi_iter.bi_size &&
+	    bio->bi_iter.bi_size > bio_max_size(bio) - len)
 		return true;
 
 	return false;

-- 
Jens Axboe