From: Andrew Morton <akpm@linux-foundation.org>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Song Liu <song@kernel.org>, Yu Kuai <yukuai3@huawei.com>,
linux-raid@vger.kernel.org
Subject: Re: [PATCH] lib/raid6: Replace custom zero page with ZERO_PAGE
Date: Sat, 15 Mar 2025 23:33:29 -0700 [thread overview]
Message-ID: <20250315233329.0b42e28a9f11e2c1b8b17ea0@linux-foundation.org> (raw)
In-Reply-To: <Z9Zm9nPjU9kT1lt5@gondor.apana.org.au>
On Sun, 16 Mar 2025 13:51:50 +0800 Herbert Xu <herbert@gondor.apana.org.au> wrote:
> > Is there any possibility that the MD drivers will point DMA hardware at
> > the global zero page, thereby invalidating that page from CPU caches in
> > some manner?
>
> The only spots that can hand this off to DMA are:
Cool, thanks for checking.
> crypto/async_tx/async_pq.c: srcs[i] = (void*)raid6_empty_zero_page;
> crypto/async_tx/async_raid6_recov.c: ptrs[i] = (void *) raid6_empty_zero_page;
> crypto/async_tx/async_raid6_recov.c: ptrs[i] = (void*)raid6_empty_zero_page;
>
> But they all turn out to be synchronous fallback code paths that
> do not involve DMA at all.
And all three cast a pointer to a void* ;)
prev parent reply other threads:[~2025-03-16 6:33 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-15 8:06 [PATCH] lib/raid6: Replace custom zero page with ZERO_PAGE Herbert Xu
2025-03-16 4:06 ` Andrew Morton
2025-03-16 5:51 ` Herbert Xu
2025-03-16 6:33 ` Andrew Morton [this message]
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