From: Michal Hocko <mhocko@suse.com>
To: osalvador@suse.de
Cc: Shijie Luo <luoshijie1@huawei.com>,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, linmiaohe@huawei.com,
linfeilong@huawei.com
Subject: Re: [PATCH] mm: fix potential pte_unmap_unlock pte error
Date: Fri, 16 Oct 2020 15:15:31 +0200 [thread overview]
Message-ID: <20201016131531.GK22589@dhcp22.suse.cz> (raw)
In-Reply-To: <20201016131112.GJ22589@dhcp22.suse.cz>
On Fri 16-10-20 15:11:17, Michal Hocko wrote:
> On Fri 16-10-20 14:37:08, osalvador@suse.de wrote:
> > On 2020-10-16 14:31, Michal Hocko wrote:
> > > I do not like the fix though. The code is really confusing. Why should
> > > we check for flags in each iteration of the loop when it cannot change?
> > > Also why should we take the ptl lock in the first place when the look is
> > > broken out immediately?
> >
> > About checking the flags:
> >
> > https://lore.kernel.org/linux-mm/20190320081643.3c4m5tec5vx653sn@d104.suse.de/#t
>
> This didn't really help. Maybe the code was different back then but
> right now the code doesn't make much sense TBH. The only reason to check
> inside the loop would be to have a completely unpopulated address range.
> Note about MPOL_MF_STRICT is not checked explicitly and I do not see how
> it makes any difference.
Ohh, I have missed queue_pages_required. Let me think some more.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-10-16 13:15 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-15 12:15 [PATCH] mm: fix potential pte_unmap_unlock pte error Shijie Luo
2020-10-15 12:58 ` osalvador
2020-10-15 13:19 ` Shijie Luo
2020-10-16 12:31 ` Michal Hocko
2020-10-16 12:37 ` osalvador
2020-10-16 13:11 ` Michal Hocko
2020-10-16 13:15 ` Michal Hocko [this message]
2020-10-16 13:42 ` Michal Hocko
2020-10-16 14:05 ` osalvador
2020-10-17 1:55 ` Shijie Luo
2021-01-09 8:01 [PATCH] mm: Fix " Miaohe Lin
2021-01-10 17:14 ` Andi Kleen
2021-01-14 2:51 ` Miaohe Lin
2021-01-22 8:27 ` Miaohe Lin
2021-01-24 2:01 ` Andrew Morton
2021-01-25 2:04 ` Miaohe Lin
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