linux-kernel - Re: [PATCH] mm: use in_atomic() in print_vma

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Message-ID: <20171106121222.nnzrr4cb7s7y5h74@dhcp22.suse.cz>
Date:   Mon, 6 Nov 2017 13:12:22 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Bart Van Assche <Bart.VanAssche@....com>,
        "yang.s@...baba-inc.com" <yang.s@...baba-inc.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "joe@...ches.com" <joe@...ches.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "mingo@...hat.com" <mingo@...hat.com>
Subject: Re: [PATCH] mm: use in_atomic() in print_vma_addr()

On Mon 06-11-17 13:00:25, Peter Zijlstra wrote:
> On Mon, Nov 06, 2017 at 11:43:54AM +0100, Michal Hocko wrote:
> > > Yes the comment is very much accurate.
> > 
> > Which suggests that print_vma_addr might be problematic, right?
> > Shouldn't we do trylock on mmap_sem instead?
> 
> Yes that's complete rubbish. trylock will get spurious failures to print
> when the lock is contended.

Yes, but I guess that it is acceptable to to not print the state under
that condition.
-- 
Michal Hocko
SUSE Labs