From: Matthew Wilcox <willy@infradead.org>
To: Peter Collingbourne <pcc@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] mm: use compare-exchange operation to set KASAN page tag
Date: Thu, 13 Jan 2022 03:32:38 +0000 [thread overview]
Message-ID: <Yd+dVmATnfdMfQVN@casper.infradead.org> (raw)
In-Reply-To: <20220113031434.464992-1-pcc@google.com>
On Wed, Jan 12, 2022 at 07:14:34PM -0800, Peter Collingbourne wrote:
> It has been reported that the tag setting operation on newly-allocated
> pages can cause the page flags to be corrupted when performed
> concurrently with other flag updates as a result of the use of
> non-atomic operations. Fix the problem by using a compare-exchange
> loop to update the tag.
I really dislike it that kasan has taken some page flags for its use.
I would much prefer it if kasan used some page_ext_flags. It's somewhat
slower to access them, and they take up a bit of extra space (unless
you already have CONFIG_PAGE_EXTENSION enabled). But page flags are a
really scarce resource and kasan has taken 9.
next prev parent reply other threads:[~2022-01-13 3:32 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-13 3:14 [PATCH] mm: use compare-exchange operation to set KASAN page tag Peter Collingbourne
2022-01-13 3:32 ` Matthew Wilcox [this message]
2022-01-14 21:58 ` Andrey Konovalov
2022-01-18 22:38 ` Peter Collingbourne
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