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SubjectRe: [PATCH v2] mm/ksm: ignore STABLE_FLAG of rmap_item->address in rmap_walk_ksm
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?

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