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From: Andrew Morton <akpm@linux-foundation.org>
To: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-doc@vger.kernel.org, rientjes@google.com, pjt@google.com,
	weixugc@google.com, gthelen@google.com, mingo@redhat.com,
	corbet@lwn.net, will@kernel.org, rppt@kernel.org,
	keescook@chromium.org, tglx@linutronix.de, peterz@infradead.org,
	masahiroy@kernel.org, samitolvanen@google.com,
	dave.hansen@linux.intel.com, x86@kernel.org, frederic@kernel.org,
	hpa@zytor.com, aneesh.kumar@linux.ibm.com, jirislaby@kernel.org,
	songmuchun@bytedance.com, qydwhotmail@gmail.com
Subject: Re: [PATCH v2 3/4] mm: page table check
Date: Tue, 7 Dec 2021 16:05:08 -0800	[thread overview]
Message-ID: <20211207160508.6ef48f273c1ae14c0d02c6ac@linux-foundation.org> (raw)
In-Reply-To: <20211204182314.1470076-4-pasha.tatashin@soleen.com>

On Sat,  4 Dec 2021 18:23:13 +0000 Pasha Tatashin <pasha.tatashin@soleen.com> wrote:

> Check user page table entries at the time they are added and removed.
> 
> Allows to synchronously catch memory corruption issues related to double
> mapping.
> 
> When a pte for an anonymous page is added into page table, we verify that
> this pte does not already point to a file backed page, and vice versa if
> this is a file backed page that is being added we verify that this page
> does not have an anonymous mapping
> 
> We also enforce that read-only sharing for anonymous pages is allowed
> (i.e.  cow after fork).  All other sharing must be for file pages.
> 
> Page table check allows to protect and debug cases where "struct page"
> metadata became corrupted for some reason.  For example, when refcnt or
> mapcount become invalid.
> 
> ...
>
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -1307,6 +1307,9 @@ config HAVE_ARCH_PFN_VALID
>  config ARCH_SUPPORTS_DEBUG_PAGEALLOC
>  	bool
>  
> +config ARCH_SUPPORTS_PAGE_TABLE_CHECK
> +	bool
> +

I guess a dependency on CONFIG_DEBUG_VM would be appropriate?



  reply	other threads:[~2021-12-08  0:05 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-04 18:23 [PATCH v2 0/4] page table check Pasha Tatashin
2021-12-04 18:23 ` [PATCH v2 1/4] mm: change page type prior to adding page table entry Pasha Tatashin
2021-12-04 18:23 ` [PATCH v2 2/4] mm: ptep_clear() page table helper Pasha Tatashin
2021-12-04 18:23 ` [PATCH v2 3/4] mm: page table check Pasha Tatashin
2021-12-08  0:05   ` Andrew Morton [this message]
2021-12-08 17:35     ` Pasha Tatashin
2021-12-04 18:23 ` [PATCH v2 4/4] x86: mm: add x86_64 support for " Pasha Tatashin
2021-12-21 13:09 ` [PATCH v2 0/4] " Fusion Future
2021-12-21 14:48   ` Pasha Tatashin

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