linux-kernel - [PATCH v5 29/44] block: kmsan: skip bio block merging logic for KMSAN

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Message-ID: <20220826150807.723137-30-glider@google.com>
Date:   Fri, 26 Aug 2022 17:07:52 +0200
From:   Alexander Potapenko <glider@...gle.com>
To:     glider@...gle.com
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Christoph Hellwig <hch@....de>,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Ilya Leoshkevich <iii@...ux.ibm.com>,
        Ingo Molnar <mingo@...hat.com>, Jens Axboe <axboe@...nel.dk>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Kees Cook <keescook@...omium.org>,
        Marco Elver <elver@...gle.com>,
        Mark Rutland <mark.rutland@....com>,
        Matthew Wilcox <willy@...radead.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Pekka Enberg <penberg@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Vegard Nossum <vegard.nossum@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>, kasan-dev@...glegroups.com,
        linux-mm@...ck.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org, Eric Biggers <ebiggers@...gle.com>
Subject: [PATCH v5 29/44] block: kmsan: skip bio block merging logic for KMSAN

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@...gle.com>
Signed-off-by: Alexander Potapenko <glider@...gle.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);
 }
 
-- 
2.37.2.672.g94769d06f0-goog