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From: Andrew Morton <akpm@linux-foundation.org>
To: Jia He <hejianet@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
	Minchan Kim <minchan@kernel.org>,
	Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>,
	Arvind Yadav <arvind.yadav.cs@gmail.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	jia.he@hxt-semitech.com, Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH v2] mm/ksm: ignore STABLE_FLAG of rmap_item->address in rmap_walk_ksm
Date: Wed, 9 May 2018 16:31:01 -0700	[thread overview]
Message-ID: <20180509163101.02f23de1842a822c61fc68ff@linux-foundation.org> (raw)
In-Reply-To: <1525403506-6750-1-git-send-email-hejianet@gmail.com>

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?

  parent reply	other threads:[~2018-05-09 23:31 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-03  8:34 [PATCH] mm/ksm: ignore STABLE_FLAG of rmap_item->address in rmap_walk_ksm Jia He
2018-05-03 10:44 ` Claudio Imbrenda
2018-05-03 13:23   ` Jia He
2018-05-04  3:11   ` [PATCH v2] " Jia He
2018-05-04  5:56     ` Jia He
2018-05-09 23:31     ` Andrew Morton [this message]
2018-05-10  1:26       ` Jia He
2018-05-10  1:26         ` Jia He
2018-05-14  9:09         ` Suzuki K Poulose
2018-05-14  9:09           ` Suzuki K Poulose
2018-05-14  9:45       ` Suzuki K Poulose
2018-05-24  8:44         ` Suzuki K Poulose
2018-05-24  8:44           ` Suzuki K Poulose
2018-05-24  8:50           ` Jia He
2018-05-24  9:01             ` Suzuki K Poulose
2018-05-24  9:01               ` Suzuki K Poulose
2018-05-24  9:36               ` Jia He
2018-05-24  9:36                 ` Jia He
2018-05-24 20:38           ` Andrew Morton
2018-06-07 22:13             ` Andrew Morton
2018-06-07 23:38               ` Andrea Arcangeli
2018-06-08  1:32                 ` Jia He
2018-06-08  1:23               ` Jia He
2018-06-08 11:08               ` Suzuki K Poulose
2018-05-03 13:41 ` [PATCH] " Michal Hocko

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