Messages in this thread | | | Subject | Re: [PATCH v3 0/9] Fixup page directory freeing | From | "Aneesh Kumar K.V" <> | Date | Tue, 14 Jan 2020 17:58:58 +0530 |
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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
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