[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20220915135838.8ad6df0363ccbd671d9641a1@linux-foundation.org>
Date: Thu, 15 Sep 2022 13:58:38 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Alexander Potapenko <glider@...gle.com>
Cc: Alexander Viro <viro@...iv.linux.org.uk>,
Alexei Starovoitov <ast@...nel.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 Biggers <ebiggers@...nel.org>,
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>,
Stephen Rothwell <sfr@...b.auug.org.au>,
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
Subject: Re: [PATCH v7 27/43] kmsan: disable physical page merging in biovec
On Thu, 15 Sep 2022 17:04:01 +0200 Alexander Potapenko <glider@...gle.com> wrote:
> KMSAN metadata for adjacent physical pages may not be adjacent,
> therefore accessing such pages together may lead to metadata
> corruption.
> We disable merging pages in biovec to prevent such corruptions.
>
> ...
>
> --- a/block/blk.h
> +++ b/block/blk.h
> @@ -88,6 +88,13 @@ static inline bool biovec_phys_mergeable(struct request_queue *q,
> phys_addr_t addr1 = page_to_phys(vec1->bv_page) + vec1->bv_offset;
> phys_addr_t addr2 = page_to_phys(vec2->bv_page) + vec2->bv_offset;
>
> + /*
> + * Merging adjacent physical pages may not work correctly under KMSAN
> + * if their metadata pages aren't adjacent. Just disable merging.
> + */
> + if (IS_ENABLED(CONFIG_KMSAN))
> + return false;
> +
> if (addr1 + vec1->bv_len != addr2)
> return false;
> if (xen_domain() && !xen_biovec_phys_mergeable(vec1, vec2->bv_page))
What are the runtime effects of this? In other words, how much
slowdown is this likely to cause in a reasonable worst-case?
Powered by blists - more mailing lists