Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
MIME-Version: 1.0
References: <CABWYdi2a=Tc3dRfQ+037PG0GHKvZd5SEXJxBBbNspsrHK1zNpQ@mail.gmail.com>
 <CABWYdi1PeNbgnM4qE001+_BzHJxQcaaY9sLOK=Y7gjqfXZO0=g@mail.gmail.com>
 <YjA439FwajtHsahr@google.com> <YjEOiZCLBMgbw8oc@google.com>
 <CABWYdi0jd_pG_qqAnnGK6otNNXeNoiAWtmC14Jv+tiSadJPw0w@mail.gmail.com>
 <CABWYdi2gOzAK60gLYKx9gSoSfJRZaAjyAWm+55gLgcSKrDrP9Q@mail.gmail.com>
 <YjTCF37cUNz9FwGi@google.com> <YjTVVxIAsnKAXjTd@google.com>
In-Reply-To: <YjTVVxIAsnKAXjTd@google.com>
From:   Ivan Babrou <ivan@cloudflare.com>
Date:   Thu, 24 Mar 2022 19:10:14 -0700
Message-ID: <CABWYdi0tgau=trCiGWULY88Wu1-=13ck8NikV0KxfDQHFCCiMA@mail.gmail.com>
Subject: Re: zram corruption due to uninitialized do_swap_page fault
To:     Minchan Kim <minchan@kernel.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Linux MM <linux-mm@kvack.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Nitin Gupta <ngupta@vflare.org>,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        kernel-team <kernel-team@cloudflare.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Fri, Mar 18, 2022 at 11:54 AM Minchan Kim <minchan@kernel.org> wrote:
>
> On Fri, Mar 18, 2022 at 10:32:07AM -0700, Minchan Kim wrote:
> > On Fri, Mar 18, 2022 at 09:30:09AM -0700, Ivan Babrou wrote:
> > > On Wed, Mar 16, 2022 at 11:26 AM Ivan Babrou <ivan@cloudflare.com> wrote:
> > > > I'm making an internal build and will push it to some location to see
> > > > how it behaves, but it might take a few days to get any sort of
> > > > confidence in the results (unless it breaks immediately).
> > > >
> > > > I've also pushed my patch that disables SWP_SYNCHRONOUS_IO to a few
> > > > locations yesterday to see how it fares.
> > >
> > > I have some updates before the weekend. There are two experimental groups:
> > >
> > > * My patch that removes the SWP_SYNCHRONOUS_IO flag. There are 704
> > > machines in this group across 5 datacenters with cumulative uptime of
> > > 916 days.
> > > * Minchan's patch to remove swap_slot_free_notify. There are 376
> > > machines in this group across 3 datacenters with cumulative uptime of
> > > 240 days.
> > >
> > > Our machines take a couple of hours to start swapping anything after
> > > boot, and I discounted these two hours from the cumulative uptime.
> > >
> > > Neither of these two groups experienced unexpected coredumps or
> > > rocksdb corruptions.
> > >
> > > I think at this point it's reasonable to proceed with Minchan's patch
> > > (including a backport).
> >
> > Let me cook the patch and then will post it.
> >
> > Thanks for the testing as well as reporting, Ivan!
>
> From 1ede54d46f0b1958bfc624f17fe709637ef8f12a Mon Sep 17 00:00:00 2001
> From: Minchan Kim <minchan@kernel.org>
> Date: Tue, 15 Mar 2022 14:14:23 -0700
> Subject: [PATCH] mm: fix unexpected zeroed page mapping with zram swap

Is there any action needed from me to make sure that this lands into
the mm tree and eventually into stable releases?