From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>,
Michael Ellerman <mpe@ellerman.id.au>
Cc: akpm@linux-foundation.org, will@kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH v3 0/9] Fixup page directory freeing
Date: Tue, 14 Jan 2020 17:58:58 +0530 [thread overview]
Message-ID: <ed2e6567-30db-a3c7-2973-a307bf2dfa7b@linux.ibm.com> (raw)
In-Reply-To: <20200114105002.GD2844@hirez.programming.kicks-ass.net>
On 1/14/20 4:20 PM, Peter Zijlstra wrote:
> On Tue, Jan 14, 2020 at 03:31:36PM +0530, Aneesh Kumar K.V wrote:
>> This is a repost of patch series from Peter with the arch specific changes except ppc64 dropped.
>> ppc64 changes are added here because we are redoing the patch series on top of ppc64 changes. This makes it
>> easy to backport these changes. Only the first 3 patches need to be backported to stable.
>>
>> The thing is, on anything SMP, freeing page directories should observe the
>> exact same order as normal page freeing:
>>
>> 1) unhook page/directory
>> 2) TLB invalidate
>> 3) free page/directory
>>
>> Without this, any concurrent page-table walk could end up with a Use-after-Free.
>> This is esp. trivial for anything that has software page-table walkers
>> (HAVE_FAST_GUP / software TLB fill) or the hardware caches partial page-walks
>> (ie. caches page directories).
>>
>> Even on UP this might give issues since mmu_gather is preemptible these days.
>> An interrupt or preempted task accessing user pages might stumble into the free
>> page if the hardware caches page directories.
>>
>> This patch series fixup ppc64 and add generic MMU_GATHER changes to support the conversion of other architectures.
>> I haven't added patches w.r.t other architecture because they are yet to be acked.
>
> Obviously looks good to me; will you route this through the Power tree
> since you're in a hurry to see this fixed?
>
Michael,
Can you take this via your tree?
-aneesh
next prev parent reply other threads:[~2020-01-14 12:29 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-14 10:01 Aneesh Kumar K.V
2020-01-14 10:01 ` [PATCH v3 1/9] powerpc/mmu_gather: Enable RCU_TABLE_FREE even for !SMP case Aneesh Kumar K.V
2020-01-14 10:01 ` [PATCH v3 2/9] mm/mmu_gather: Invalidate TLB correctly on batch allocation failure and flush Aneesh Kumar K.V
2020-01-14 10:01 ` [PATCH v3 3/9] asm-generic/tlb: Avoid potential double flush Aneesh Kumar K.V
2020-01-14 10:01 ` [PATCH v3 4/9] asm-gemeric/tlb: Remove stray function declarations Aneesh Kumar K.V
2020-01-14 10:01 ` [PATCH v3 5/9] asm-generic/tlb: Add missing CONFIG symbol Aneesh Kumar K.V
2020-01-14 10:01 ` [PATCH v3 6/9] asm-generic/tlb: Rename HAVE_RCU_TABLE_FREE Aneesh Kumar K.V
2020-01-14 10:01 ` [PATCH v3 7/9] asm-generic/tlb: Rename HAVE_MMU_GATHER_PAGE_SIZE Aneesh Kumar K.V
2020-01-14 10:01 ` [PATCH v3 8/9] asm-generic/tlb: Rename HAVE_MMU_GATHER_NO_GATHER Aneesh Kumar K.V
2020-01-14 10:01 ` [PATCH v3 9/9] asm-generic/tlb: Provide MMU_GATHER_TABLE_FREE Aneesh Kumar K.V
2020-01-14 10:50 ` [PATCH v3 0/9] Fixup page directory freeing Peter Zijlstra
2020-01-14 12:28 ` Aneesh Kumar K.V [this message]
2020-01-15 0:25 ` Andrew Morton
2020-01-15 14:47 ` Aneesh Kumar K.V
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