linux-kernel - Re: [PATCH] xen/gntdev: fix up blockable calls to mn_invl_range

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Message-ID: <565d0ef0-4723-bd1b-95de-cb9aba50fe20@oracle.com>
Date:   Thu, 23 Aug 2018 09:46:40 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Michal Hocko <mhocko@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        linux-mm@...ck.org, xen-devel@...ts.xenproject.org,
        LKML <linux-kernel@...r.kernel.org>,
        Michal Hocko <mhocko@...e.com>, Juergen Gross <jgross@...e.com>
Subject: Re: [PATCH] xen/gntdev: fix up blockable calls to mn_invl_range_start

On 08/23/2018 08:07 AM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@...e.com>
>
> 93065ac753e4 ("mm, oom: distinguish blockable mode for mmu notifiers")
> has introduced blockable parameter to all mmu_notifiers and the notifier
> has to back off when called in !blockable case and it could block down
> the road.
>
> The above commit implemented that for mn_invl_range_start but both
> in_range checks are done unconditionally regardless of the blockable
> mode and as such they would fail all the time for regular calls.
> Fix this by checking blockable parameter as well.
>
> Once we are there we can remove the stale TODO. The lock has to be
> sleepable because we wait for completion down in gnttab_unmap_refs_sync.
>
> Fixes: 93065ac753e4 ("mm, oom: distinguish blockable mode for mmu notifiers")
> Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> Cc: Juergen Gross <jgross@...e.com>
> Signed-off-by: Michal Hocko <mhocko@...e.com>

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cel.com>