Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Fri, 9 Jun 2023 16:45:44 -0400
From:   Peter Xu <peterx@redhat.com>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Suren Baghdasaryan <surenb@google.com>, akpm@linux-foundation.org,
        hannes@cmpxchg.org, mhocko@suse.com, josef@toxicpanda.com,
        jack@suse.cz, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com,
        michel@lespinasse.org, liam.howlett@oracle.com, jglisse@google.com,
        vbabka@suse.cz, minchan@google.com, dave@stgolabs.net,
        punit.agrawal@bytedance.com, lstoakes@gmail.com, hdanton@sina.com,
        apopple@nvidia.com, ying.huang@intel.com, david@redhat.com,
        yuzhao@google.com, dhowells@redhat.com, hughd@google.com,
        viro@zeniv.linux.org.uk, brauner@kernel.org,
        pasha.tatashin@soleen.com, linux-mm@kvack.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        kernel-team@android.com
Subject: Re: [PATCH v2 2/6] mm: handle swap page faults under VMA lock if
 page is uncontended
Message-ID: <ZIOPeNAy7viKNU5Z@x1n>
References: <20230609005158.2421285-1-surenb@google.com>
 <20230609005158.2421285-3-surenb@google.com>
 <ZIOKxoTlRzWQtQQR@x1n>
 <ZIONJQGuhYiDnFdg@casper.infradead.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <ZIONJQGuhYiDnFdg@casper.infradead.org>
Precedence: bulk

On Fri, Jun 09, 2023 at 09:35:49PM +0100, Matthew Wilcox wrote:
> On Fri, Jun 09, 2023 at 04:25:42PM -0400, Peter Xu wrote:
> > >  bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm,
> > >  			 unsigned int flags)
> > >  {
> > > +	/* Can't do this if not holding mmap_lock */
> > > +	if (flags & FAULT_FLAG_VMA_LOCK)
> > > +		return false;
> > 
> > If here what we need is the page lock, can we just conditionally release
> > either mmap lock or vma lock depending on FAULT_FLAG_VMA_LOCK?
> 
> See patch 5 ...

Just reaching.. :)

Why not in one shot, then?

-- 
Peter Xu