linux-kernel - Re: mlockall(MCL_CURRENT) blocking infinitely

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Message-ID: <20191106120402.GG16085@quack2.suse.cz>
Date:   Wed, 6 Nov 2019 13:04:02 +0100
From:   Jan Kara <jack@...e.cz>
To:     snazy@...zy.de
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...nel.org>,
        Josef Bacik <josef@...icpanda.com>, Jan Kara <jack@...e.cz>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Randy Dunlap <rdunlap@...radead.org>,
        linux-kernel@...r.kernel.org, Linux MM <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Potyra, Stefan" <Stefan.Potyra@...ktrobit.com>
Subject: Re: mlockall(MCL_CURRENT) blocking infinitely

On Wed 06-11-19 12:26:24, Robert Stupp wrote:
> Maybe a native and wrong idea, but would it work to call
> __get_user_pages_locked() instead of __get_user_pages() in
> populate_vma_page_range() ?

See my reply to Johannes. It would work but it would be somewhat fragile.

								Honza

> On Wed, 2019-11-06 at 11:25 +0100, Robert Stupp wrote:
> > Here's one more dmesg output with more information captured in
> > __get_user_pages() as well. It basically confirms that
> > handle_mm_fault() returns VM_FAULT_RETRY.
> >
> > I'm not sure where and what to change ("fix with a FOLL_TRIED
> > somewhere") to make it work. My (uneducated) impression is, that only
> > __get_user_pages() needs to be changed - but I might be wrong.
> >
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR