From: Vitaly Wool <vitalywool@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Henry Burns <henryburns@google.com>,
Shakeel Butt <shakeelb@google.com>,
Vitaly Vul <vitaly.vul@sony.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Xidong Wang <wangxidong_97@163.com>,
Jonathan Adams <jwadams@google.com>,
Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] mm/z3fold.c: Lock z3fold page before __SetPageMovable()
Date: Wed, 3 Jul 2019 07:53:32 +0200 [thread overview]
Message-ID: <CAMJBoFOhXP36L6pZEA-7p24mJweDGe9iYb2fo1nNCxadYHcPzQ@mail.gmail.com> (raw)
In-Reply-To: <20190702152409.21c6c3787d125d61fb47840a@linux-foundation.org>
On Wed, Jul 3, 2019 at 12:24 AM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Tue, 2 Jul 2019 15:17:47 -0700 Henry Burns <henryburns@google.com> wrote:
>
> > > > > > + if (can_sleep) {
> > > > > > + lock_page(page);
> > > > > > + __SetPageMovable(page, pool->inode->i_mapping);
> > > > > > + unlock_page(page);
> > > > > > + } else {
> > > > > > + if (!WARN_ON(!trylock_page(page))) {
> > > > > > + __SetPageMovable(page, pool->inode->i_mapping);
> > > > > > + unlock_page(page);
> > > > > > + } else {
> > > > > > + pr_err("Newly allocated z3fold page is locked\n");
> > > > > > + WARN_ON(1);
>
> The WARN_ON will have already warned in this case.
>
> But the whole idea of warning in this case may be undesirable. We KNOW
> that the warning will sometimes trigger (yes?). So what's the point in
> scaring users?
Well, normally a newly allocated page that we own should not be locked
by someone else so this is worth a warning IMO. With that said, the
else branch here appears to be redundant.
~Vitaly
next prev parent reply other threads:[~2019-07-03 5:54 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-02 0:51 [PATCH v2] mm/z3fold.c: Lock z3fold page before __SetPageMovable() Henry Burns
2019-07-02 1:00 ` Shakeel Butt
2019-07-02 1:16 ` Henry Burns
2019-07-02 21:19 ` Andrew Morton
2019-07-02 22:17 ` Henry Burns
2019-07-02 22:24 ` Andrew Morton
2019-07-03 5:53 ` Vitaly Wool [this message]
2019-07-03 16:39 ` Henry Burns
2019-07-03 5:54 ` Vitaly Wool
2019-07-02 9:53 ` Vitaly Wool
2019-07-02 18:58 ` David Rientjes
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