From: Andrew Morton <akpm@linux-foundation.org>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: peterz@infradead.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 16:25:26 -0800 [thread overview]
Message-ID: <20200114162526.87863ebce00695cc979b5217@linux-foundation.org> (raw)
In-Reply-To: <20200114100145.365527-1-aneesh.kumar@linux.ibm.com>
On Tue, 14 Jan 2020 15:31:36 +0530 "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> 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.
But none of these patches had a cc:stable in the changelog?
> 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.
next prev parent reply other threads:[~2020-01-15 0:25 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-14 10:01 [PATCH v3 0/9] Fixup page directory freeing 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
2020-01-15 0:25 ` Andrew Morton [this message]
2020-01-15 14:47 ` Aneesh Kumar K.V
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