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From: Dennis Zhou <dennis@kernel.org>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Tejun Heo <tj@kernel.org>, Christoph Lameter <cl@linux.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] percpu: flush tlb after pcpu_depopulate_chunk()
Date: Sat, 3 Jul 2021 05:25:02 +0000	[thread overview]
Message-ID: <YN/0rmO0p6IJcImj@google.com> (raw)
In-Reply-To: <20210703051444.GA3786429@roeck-us.net>

On Fri, Jul 02, 2021 at 10:14:44PM -0700, Guenter Roeck wrote:
> On Sat, Jul 03, 2021 at 04:04:49AM +0000, Dennis Zhou wrote:
> > Prior to "percpu: implement partial chunk depopulation",
> > pcpu_depopulate_chunk() was called only on the destruction path. This
> > meant the virtual address range was on its way back to vmalloc which
> > will handle flushing the tlbs for us.
> > 
> > However, now that we call pcpu_depopulate_chunk() during the active
> > lifecycle of a chunk, we need to flush the tlb as well otherwise we can
> > end up accessing the wrong page through an invalid tlb mapping.
> > 
> > This was reported in [1].
> > 
> > [1] https://lore.kernel.org/lkml/20210702191140.GA3166599@roeck-us.net/
> > 
> > Fixes: f183324133ea ("percpu: implement partial chunk depopulation")
> > Reported-by: Guenter Roeck <linux@roeck-us.net>
> > Signed-off-by: Dennis Zhou <dennis@kernel.org>
> 
> Tested-by: Guenter Roeck <linux@roeck-us.net>
> 
> Thanks!
> Guenter
>

I updated the tag and have applied this to for-5.14-fixes so it can get
some for-next exposure before I send a fix to Linus.

Thanks for setting up the super easy repro! It made debugging this
significantly easier.

Thanks,
Dennis

  reply	other threads:[~2021-07-03  5:25 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-03  5:14 [PATCH] percpu: flush tlb after pcpu_depopulate_chunk() Guenter Roeck
2021-07-03  5:25 ` Dennis Zhou [this message]
2021-07-03 16:57   ` Dennis Zhou
  -- strict thread matches above, loose matches on Subject: below --
2021-07-03  4:04 Dennis Zhou

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