From: Will Deacon <will.deacon@arm.com>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
catalin.marinas@arm.com, akpm@linux-foundation.org,
hanjun.guo@linaro.org, xieyisheng1@huawei.com,
rrichter@cavium.com, james.morse@arm.com
Subject: Re: [PATCH 1/2] mm: don't dereference struct page fields of invalid pages
Date: Wed, 4 Jan 2017 12:16:41 +0000 [thread overview]
Message-ID: <20170104121641.GC18193@arm.com> (raw)
In-Reply-To: <1481706707-6211-2-git-send-email-ard.biesheuvel@linaro.org>
On Wed, Dec 14, 2016 at 09:11:46AM +0000, Ard Biesheuvel wrote:
> The VM_BUG_ON() check in move_freepages() checks whether the node
> id of a page matches the node id of its zone. However, it does this
> before having checked whether the struct page pointer refers to a
> valid struct page to begin with. This is guaranteed in most cases,
> but may not be the case if CONFIG_HOLES_IN_ZONE=y.
>
> So reorder the VM_BUG_ON() with the pfn_valid_within() check.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
> mm/page_alloc.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index f64e7bcb43b7..4e298e31fa86 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1864,14 +1864,14 @@ int move_freepages(struct zone *zone,
> #endif
>
> for (page = start_page; page <= end_page;) {
> - /* Make sure we are not inadvertently changing nodes */
> - VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page);
> -
> if (!pfn_valid_within(page_to_pfn(page))) {
> page++;
> continue;
> }
>
> + /* Make sure we are not inadvertently changing nodes */
> + VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page);
> +
> if (!PageBuddy(page)) {
> page++;
> continue;
Acked-by: Will Deacon <will.deacon@arm.com>
I'm guessing akpm can pick this up as a non-urgent fix.
Will
next prev parent reply other threads:[~2017-01-04 12:17 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-14 9:11 [PATCH 0/2] arm64: numa: fix spurious BUG() on NOMAP regions Ard Biesheuvel
2016-12-14 9:11 ` [PATCH 1/2] mm: don't dereference struct page fields of invalid pages Ard Biesheuvel
2017-01-04 12:16 ` Will Deacon [this message]
2016-12-14 9:11 ` [PATCH 2/2] arm64: mm: enable CONFIG_HOLES_IN_ZONE for NUMA Ard Biesheuvel
2016-12-15 15:39 ` Robert Richter
2016-12-15 16:07 ` Ard Biesheuvel
2016-12-16 17:10 ` Robert Richter
2016-12-16 1:57 ` Hanjun Guo
2016-12-16 17:14 ` Robert Richter
2017-01-04 13:28 ` Will Deacon
2017-01-04 13:50 ` Ard Biesheuvel
2017-01-04 14:02 ` Will Deacon
2017-01-05 11:24 ` Robert Richter
2017-01-05 12:08 ` Will Deacon
2017-01-05 12:22 ` Robert Richter
2017-01-05 19:49 ` Robert Richter
2017-01-06 12:03 ` Will Deacon
2017-01-06 12:22 ` Ard Biesheuvel
2017-02-06 13:36 ` Robert Richter
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