Linux-Fsdevel Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Nikolaus Rath <Nikolaus@rath.org>
To: Gabriel Krisman Bertazi <krisman@collabora.com>
Cc: "Matthew Wilcox" <willy@infradead.org>,
	linux-fsdevel@vger.kernel.org,
	fuse-devel <fuse-devel@lists.sourceforge.net>,
	linux-mm <linux-mm@kvack.org>, miklos <mszeredi@redhat.com>,
	"André Almeida" <andrealmeid@collabora.com>
Subject: Re: [fuse-devel] fuse: trying to steal weird page
Date: Sun, 03 May 2020 21:25:16 +0100	[thread overview]
Message-ID: <87zhaoydeb.fsf@vostro.rath.org> (raw)
In-Reply-To: <85d07kkh4d.fsf@collabora.com> (Gabriel Krisman Bertazi's message of "Sun, 03 May 2020 14:28:34 -0400")

On May 03 2020, Gabriel Krisman Bertazi <krisman@collabora.com> wrote:
> Matthew Wilcox <willy@infradead.org> writes:
>
>> On Sun, May 03, 2020 at 09:43:41AM +0100, Nikolaus Rath wrote:
>>> Here's what I got:
>>> 
>>> [  221.277260] page:ffffec4bbd639880 refcount:1 mapcount:0 mapping:0000000000000000 index:0xd9
>>> [  221.277265] flags: 0x17ffffc0000097(locked|waiters|referenced|uptodate|lru)
>>> [  221.277269] raw: 0017ffffc0000097 ffffec4bbd62f048 ffffec4bbd619308 0000000000000000
>>> [  221.277271] raw: 00000000000000d9 0000000000000000 00000001ffffffff ffff9aec11beb000
>>> [  221.277272] page dumped because: fuse: trying to steal weird page
>>> [  221.277273] page->mem_cgroup:ffff9aec11beb000
>>
>> Great!  Here's the condition:
>>
>>         if (page_mapcount(page) ||
>>             page->mapping != NULL ||
>>             page_count(page) != 1 ||
>>             (page->flags & PAGE_FLAGS_CHECK_AT_PREP &
>>              ~(1 << PG_locked |
>>                1 << PG_referenced |
>>                1 << PG_uptodate |
>>                1 << PG_lru |
>>                1 << PG_active |
>>                1 << PG_reclaim))) {
>>
>> mapcount is 0, mapping is NULL, refcount is 1, so that's all fine.
>> flags has 'waiters' set, which is not in the allowed list.  I don't
>> know the internals of FUSE, so I don't know why that is.
>>
>
> On the first message, Nikolaus sent the following line:
>
>>> [ 2333.009937] fuse: page=00000000dd1750e3 index=2022240 flags=17ffffc0000097, count=1,
>>> mapcount=0, mapping=00000000125079ad
>
> It should be noted that on the second run, where we got the dump_page
> log, it indeed had a null mapping, which is similar to what Nikolaus
> asked on the previous thread he linked to, but looks like this wasn't
> the case on at least some of the reproductions of the issue.  On the
> line above, the condition that triggered the warning was page->mapping
> != NULL.  I don't know what to do with this information, though.

Indeed, that's curious. I've modified the patch slightly to print both
the old and the new message to confirm. And indeed:

[  260.882873] fuse: trying to steal weird page
[  260.882879] fuse:   page=00000000813e7570 index=2010048 flags=17ffffc0000097, count=1, mapcount=0, mapping=0000000094844a11
[  260.882882] page:ffffe13431bcc000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x1eabc0
[  260.882885] flags: 0x17ffffc0000097(locked|waiters|referenced|uptodate|lru)
[  260.882889] raw: 0017ffffc0000097 ffffe13431ca7c48 ffffe13431bcbfc8 0000000000000000
[  260.882891] raw: 00000000001eabc0 0000000000000000 00000001ffffffff ffff91fe31318000
[  260.882892] page dumped because: fuse: trying to steal weird page
[  260.882893] page->mem_cgroup:ffff91fe31318000
[  262.608438] fuse: trying to steal weird page
[  262.608444] fuse:   page=000000000c21d0c7 index=2040704 flags=17ffffc0000097, count=1, mapcount=0, mapping=0000000094844a11
[  262.608447] page:ffffe134319ebf80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x1f2380
[  262.608450] flags: 0x17ffffc0000097(locked|waiters|referenced|uptodate|lru)
[  262.608455] raw: 0017ffffc0000097 ffffe134319e9fc8 ffffe134319ebf48 0000000000000000
[  262.608457] raw: 00000000001f2380 0000000000000000 00000001ffffffff ffff91fe31318000
[  262.608458] page dumped because: fuse: trying to steal weird page
[  262.608459] page->mem_cgroup:ffff91fe31318000
[  262.770209] fuse: trying to steal weird page
[  262.770215] fuse:   page=0000000018a813ac index=2045120 flags=17ffffc0000097, count=1, mapcount=0, mapping=0000000094844a11
[  262.770218] page:ffffe134319953c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x1f34c0
[  262.770221] flags: 0x17ffffc0000097(locked|waiters|referenced|uptodate|lru)
[  262.770225] raw: 0017ffffc0000097 ffffe134319ae788 ffffe13431995388 0000000000000000
[  262.770228] raw: 00000000001f34c0 0000000000000000 00000001ffffffff ffff91fe31318000
[  262.770229] page dumped because: fuse: trying to steal weird page
[  262.770230] page->mem_cgroup:ffff91fe31318000



Best,
-Nikolaus

-- 
GPG Fingerprint: ED31 791B 2C5C 1613 AF38 8B8A D113 FCAC 3C4E 599F

             »Time flies like an arrow, fruit flies like a Banana.«

  parent reply	other threads:[~2020-05-03 20:26 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-02 19:09 Nikolaus Rath
2020-05-02 19:52 ` Nikolaus Rath
2020-05-03  3:26   ` Matthew Wilcox
2020-05-03  8:43     ` [fuse-devel] " Nikolaus Rath
2020-05-03 10:27       ` Matthew Wilcox
2020-05-03 18:28         ` Gabriel Krisman Bertazi
2020-05-03 20:06           ` Matthew Wilcox
2020-05-03 20:25           ` Nikolaus Rath [this message]
2020-05-06 13:57             ` Vlastimil Babka
2020-05-03 21:34         ` Hugh Dickins
2020-05-18 12:45         ` Miklos Szeredi
2020-05-18 14:48           ` Matthew Wilcox
2020-05-18 14:58             ` Miklos Szeredi
2020-05-18 15:26               ` Matthew Wilcox
  -- strict thread matches above, loose matches on Subject: below --
2018-12-26 21:43 Nikolaus Rath
2019-01-07  8:28 ` [fuse-devel] " Miklos Szeredi
2019-01-07 21:05   ` Nikolaus Rath
2019-01-08  8:27     ` Miklos Szeredi
2019-01-08 10:35       ` Nikolaus Rath
2019-01-09  8:07         ` Miklos Szeredi
2019-01-11 15:39           ` Nikolaus Rath
2019-01-11 15:39             ` [fuse-devel] " Nikolaus Rath
2019-02-10 22:05             ` Nikolaus Rath
2019-02-12 14:57               ` Miklos Szeredi
2019-02-12 21:28                 ` Nikolaus Rath
2019-02-25 21:41                   ` Nikolaus Rath
2019-02-26 12:57                     ` Miklos Szeredi
2019-02-26 13:30                       ` Miklos Szeredi

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87zhaoydeb.fsf@vostro.rath.org \
    --to=nikolaus@rath.org \
    --cc=andrealmeid@collabora.com \
    --cc=fuse-devel@lists.sourceforge.net \
    --cc=krisman@collabora.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mszeredi@redhat.com \
    --cc=willy@infradead.org \
    --subject='Re: [fuse-devel] fuse: trying to steal weird page' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).