[PATCH v4 29/45] block: kmsan: skip bio block merging logic for KMSAN

Alexander Potapenko
2022-07-01T14:27:35Z

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

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 51c99f2c5c908..ce6b3c82159a6 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -867,6 +867,8 @@ static inline bool page_is_mergeable(const struct bio_vec *bv,
return false;

*same_page = ((vec_end_addr & PAGE_MASK) == page_addr);
+ if (!*same_page && IS_ENABLED(CONFIG_KMSAN))
+ return false;
if (*same_page)
return true;
return (bv->bv_page + bv_end / PAGE_SIZE) == (page + off / PAGE_SIZE);
--
2.37.0.rc0.161.g10f37bed90-goog