[PATCH v7 28/43] block: kmsan: skip bio block merging logic for KMSAN

Alexander Potapenko
2022-09-15T15:10:15Z

KMSAN doesn't allow treating adjacent memory pages as such, if they were
allocated by different alloc_pages() calls.
The block layer however does so: adjacent pages end up being used
together. To prevent this, make page_is_mergeable() return false under
KMSAN.

Suggested-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Alexander Potapenko <glider@google.com>

---

v4:
-- swap block: and kmsan: in the subject

v5:
-- address Marco Elver's comments

Link: https://linux-review.googlesource.com/id/Ie29cc2464c70032347c32ab2a22e1e7a0b37b905
---
block/bio.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/block/bio.c b/block/bio.c
index 3d3a2678fea25..106ef14f28c2a 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -869,6 +869,8 @@ static inline bool page_is_mergeable(const struct bio_vec *bv,
*same_page = ((vec_end_addr & PAGE_MASK) == page_addr);
if (*same_page)
return true;
+ else if (IS_ENABLED(CONFIG_KMSAN))
+ return false;
return (bv->bv_page + bv_end / PAGE_SIZE) == (page + off / PAGE_SIZE);
}

--
2.37.2.789.g6183377224-goog