From: Andrew Morton <akpm@linux-foundation.org>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: linux-mm@kvack.org, mhocko@suse.com, zhongjiang@huawei.com,
labbott@fedoraproject.org, mark.rutland@arm.com,
linux-arm-kernel@lists.infradead.org, dave.hansen@intel.com
Subject: Re: [PATCH v5] mm: huge-vmap: fail gracefully on unexpected huge vmap mappings
Date: Thu, 15 Jun 2017 14:24:39 -0700 [thread overview]
Message-ID: <20170615142439.7a431065465c5b4691aed1cc@linux-foundation.org> (raw)
In-Reply-To: <20170609082226.26152-1-ard.biesheuvel@linaro.org>
On Fri, 9 Jun 2017 08:22:26 +0000 Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> Existing code that uses vmalloc_to_page() may assume that any
> address for which is_vmalloc_addr() returns true may be passed
> into vmalloc_to_page() to retrieve the associated struct page.
>
> This is not un unreasonable assumption to make, but on architectures
> that have CONFIG_HAVE_ARCH_HUGE_VMAP=y, it no longer holds, and we
> need to ensure that vmalloc_to_page() does not go off into the weeds
> trying to dereference huge PUDs or PMDs as table entries.
>
> Given that vmalloc() and vmap() themselves never create huge
> mappings or deal with compound pages at all, there is no correct
> answer in this case, so return NULL instead, and issue a warning.
Is this patch known to fix any current user-visible problem?
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next prev parent reply other threads:[~2017-06-15 21:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-09 8:22 Ard Biesheuvel
2017-06-09 9:22 ` Mark Rutland
2017-06-09 9:27 ` Ard Biesheuvel
2017-06-09 9:29 ` Mark Rutland
2017-06-09 18:13 ` Laura Abbott
2017-06-15 21:24 ` Andrew Morton [this message]
2017-06-15 22:11 ` Ard Biesheuvel
2017-06-15 22:16 ` Andrew Morton
2017-06-15 22:29 ` Ard Biesheuvel
2017-06-16 8:38 ` Ard Biesheuvel
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