linux-kernel - Re: [PATCH 1/3] xen/gntdev: fix up blockable calls to mn_invl_range

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Message-ID: <234d0dd0-cd42-5ca8-e6bd-cbd12c872d6d@suse.com>
Date:   Tue, 28 Aug 2018 08:03:24 +0200
From:   Juergen Gross <jgross@...e.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, LKML <linux-kernel@...r.kernel.org>,
        Michal Hocko <mhocko@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>
Subject: Re: [PATCH 1/3] xen/gntdev: fix up blockable calls to
 mn_invl_range_start

On 27/08/18 13:26, 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.
> 
> Changes since v1
> - pull in_range check into mn_invl_range_start - Juergen
> 
> 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: Juergen Gross <jgross@...e.com>


Juergen