Messages in this thread | | | Subject | Re: [PATCH v2] mm/ksm: ignore STABLE_FLAG of rmap_item->address in rmap_walk_ksm | From | Suzuki K Poulose <> | Date | Thu, 24 May 2018 10:01:03 +0100 |
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On 24/05/18 09:50, Jia He wrote: > Hi Suzuki > > On 5/24/2018 4:44 PM, Suzuki K Poulose Wrote: >> On 14/05/18 10:45, Suzuki K Poulose wrote: >>> On 10/05/18 00:31, Andrew Morton wrote: >>>> On Fri, 4 May 2018 11:11:46 +0800 Jia He <hejianet@gmail.com> wrote: >>>> >>>>> In our armv8a server(QDF2400), I noticed lots of WARN_ON caused by PAGE_SIZE >>>>> unaligned for rmap_item->address under memory pressure tests(start 20 guests >>>>> and run memhog in the host). >>>>> >>>>> ... >>>>> >>>>> In rmap_walk_ksm, the rmap_item->address might still have the STABLE_FLAG, >>>>> then the start and end in handle_hva_to_gpa might not be PAGE_SIZE aligned. >>>>> Thus it will cause exceptions in handle_hva_to_gpa on arm64. >>>>> >>>>> This patch fixes it by ignoring(not removing) the low bits of address when >>>>> doing rmap_walk_ksm. >>>>> >>>>> Signed-off-by: jia.he@hxt-semitech.com >>>> >>>> I assumed you wanted this patch to be committed as >>>> From:jia.he@hxt-semitech.com rather than From:hejianet@gmail.com, so I >>>> made that change. Please let me know if this was inappropriate. >>>> >>>> You can do this yourself by adding an explicit From: line to the very >>>> start of the patch's email text. >>>> >>>> Also, a storm of WARN_ONs is pretty poor behaviour. Is that the only >>>> misbehaviour which this bug causes? Do you think the fix should be >>>> backported into earlier kernels? >>>> >> >> >> Jia, Andrew, >> >> What is the status of this patch ? >> >> Suzuki > I thought the patch is merged into mmotm tree. > http://www.ozlabs.org/~akpm/mmotm/series > But I don't know what is the next step.
Hi Jia,
Thanks for the update. I think that should eventually hit mainline. When it does, please could you send the patch to stable kernel versions too ?
Usually having a "Cc: stable@kernel.vger.org" in the original patch (for critical fixes) would have done the trick. But since we don't have it, please send it following the stable kernel rules.
Cheers Suzuki
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